Xen devel - Nov 2011 - [PATCH] Add code to track the address of the VM generation id buffer across a

# HG changeset patch
# User Paul Durrant <paul.durrant@citrix.com>
# Date 1322686267 0
# Node ID 94a17182f386c8bb414eba55dddf763b8982c76d
# Parent  3c4c29899d8a2a0c0f9109b7236da95bb72b77b6
Add code to track the address of the VM generation id buffer across a
save/restore or migrate and inject a new value.
The address of the buffer is written into xenstore by hvmloader at
boot time. It must be read from xenstore by the caller of
xc_domain_save() and then written back again by the caller of
xc_domain_restore().

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>

diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/ia64/xc_ia64_linux_restore.c
--- a/tools/libxc/ia64/xc_ia64_linux_restore.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxc/ia64/xc_ia64_linux_restore.c	Wed Nov 30 20:51:07 2011 +0000
@@ -548,7 +548,8 @@ int
 xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                   unsigned int store_evtchn, unsigned long *store_mfn,
                   unsigned int console_evtchn, unsigned long *console_mfn,
-                  unsigned int hvm, unsigned int pae, int superpages)
+                  unsigned int hvm, unsigned int pae, int superpages,
+                  uint64_t gid)
 {
     DECLARE_DOMCTL;
     int rc = 1;
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/ia64/xc_ia64_linux_save.c
--- a/tools/libxc/ia64/xc_ia64_linux_save.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxc/ia64/xc_ia64_linux_save.c	Wed Nov 30 20:51:07 2011 +0000
@@ -382,7 +382,8 @@ out:
 int
 xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iters,
                uint32_t max_factor, uint32_t flags,
-               struct save_callbacks* callbacks, int hvm)
+               struct save_callbacks* callbacks, int hvm,
+               unsigned long vm_gid_addr)
 {
     DECLARE_DOMCTL;
     xc_dominfo_t info;
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xc_domain_restore.c
--- a/tools/libxc/xc_domain_restore.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxc/xc_domain_restore.c	Wed Nov 30 20:51:07 2011 +0000
@@ -676,6 +676,7 @@ typedef struct {
     uint64_t console_pfn;
     uint64_t acpi_ioport_location;
     uint64_t viridian;
+    uint64_t vm_gid_addr;
 } pagebuf_t;
 
 static int pagebuf_init(pagebuf_t* buf)
@@ -820,6 +821,17 @@ static int pagebuf_get_one(xc_interface 
         }
         return pagebuf_get_one(xch, ctx, buf, fd, dom);
 
+    case XC_SAVE_ID_HVM_GENERATION_ID_ADDR:
+        /* Skip padding 4 bytes then read the generation id buffer location. */
+        if ( RDEXACT(fd, &buf->vm_gid_addr, sizeof(uint32_t)) ||
+             RDEXACT(fd, &buf->vm_gid_addr, sizeof(uint64_t)) )
+        {
+            PERROR("error read the generation id buffer location");
+            return -1;
+        }
+        DPRINTF("read generation id buffer address");
+        return pagebuf_get_one(xch, ctx, buf, fd, dom);
+
     default:
         if ( (count > MAX_BATCH_SIZE) || (count < 0) ) {
             ERROR("Max batch size exceeded (%d). Giving up.", count);
@@ -1186,7 +1198,8 @@ static int apply_batch(xc_interface *xch
 int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                       unsigned int store_evtchn, unsigned long *store_mfn,
                       unsigned int console_evtchn, unsigned long *console_mfn,
-                      unsigned int hvm, unsigned int pae, int superpages)
+                      unsigned int hvm, unsigned int pae, int superpages,
+                      uint64_t gid, unsigned long *vm_gid_addr)
 {
     DECLARE_DOMCTL;
     int rc = 1, frc, i, j, n, m, pae_extended_cr3 = 0, ext_vcpucontext = 0;
@@ -1386,6 +1399,33 @@ int xc_domain_restore(xc_interface *xch,
                 xc_set_hvm_param(xch, dom, HVM_PARAM_VM86_TSS,
pagebuf.vm86_tss);
             if ( pagebuf.console_pfn )
                 console_pfn = pagebuf.console_pfn;
+            if ( pagebuf.vm_gid_addr ) {
+                unsigned int offset;
+                unsigned char *buf;
+
+                /*
+                 * Map the VM generation id buffer and inject the new value.
+                 */
+
+                pfn = pagebuf.vm_gid_addr >> PAGE_SHIFT;
+                offset = pagebuf.vm_gid_addr & (PAGE_SIZE - 1);
+            
+                if ( (pfn >= dinfo->p2m_size) ||
+                     (pfn_type[pfn] != XEN_DOMCTL_PFINFO_NOTAB) )
+                {
+                    ERROR("generation id buffer frame is bad");
+                    goto out;
+                }
+
+                mfn = ctx->p2m[pfn];
+                buf = xc_map_foreign_range(xch, dom, PAGE_SIZE,
+                                           PROT_READ | PROT_WRITE, mfn);
+                *(unsigned long long *)(buf + offset) = gid;
+                munmap(buf, PAGE_SIZE);
+
+                *vm_gid_addr = pagebuf.vm_gid_addr;
+            }
+
             break;  /* our work here is done */
         }
 
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xc_domain_save.c
--- a/tools/libxc/xc_domain_save.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxc/xc_domain_save.c	Wed Nov 30 20:51:07 2011 +0000
@@ -754,7 +754,8 @@ static int save_tsc_info(xc_interface *x
 
 int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t
max_iters,
                    uint32_t max_factor, uint32_t flags,
-                   struct save_callbacks* callbacks, int hvm)
+                   struct save_callbacks* callbacks, int hvm,
+                   unsigned long vm_gid_addr)
 {
     xc_dominfo_t info;
     DECLARE_DOMCTL;
@@ -1460,6 +1461,16 @@ int xc_domain_save(xc_interface *xch, in
             uint64_t data;
         } chunk = { 0, };
 
+        chunk.id = XC_SAVE_ID_HVM_GENERATION_ID_ADDR;
+        chunk.data = vm_gid_addr;
+
+        if ( (chunk.data != 0) &&
+             wrexact(io_fd, &chunk, sizeof(chunk)) )
+        {
+            PERROR("Error when writing the generation id buffer location
for guest");
+            goto out;
+        }
+
         chunk.id = XC_SAVE_ID_HVM_IDENT_PT;
         chunk.data = 0;
         xc_get_hvm_param(xch, dom, HVM_PARAM_IDENT_PT,
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xenguest.h
--- a/tools/libxc/xenguest.h	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxc/xenguest.h	Wed Nov 30 20:51:07 2011 +0000
@@ -57,7 +57,8 @@ struct save_callbacks {
  */
 int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t
max_iters,
                    uint32_t max_factor, uint32_t flags /* XCFLAGS_xxx */,
-                   struct save_callbacks* callbacks, int hvm);
+                   struct save_callbacks* callbacks, int hvm,
+                   unsigned long vm_gid_addr);
 
 
 /**
@@ -71,12 +72,15 @@ int xc_domain_save(xc_interface *xch, in
  * @parm hvm non-zero if this is a HVM restore
  * @parm pae non-zero if this HVM domain has PAE support enabled
  * @parm superpages non-zero to allocate guest memory with superpages
+ * @parm gid the new generation id of the VM
+ * @parm vm_gid_addr returned with the address of the generation id buffer
  * @return 0 on success, -1 on failure
  */
 int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                       unsigned int store_evtchn, unsigned long *store_mfn,
                       unsigned int console_evtchn, unsigned long *console_mfn,
-                      unsigned int hvm, unsigned int pae, int superpages);
+                      unsigned int hvm, unsigned int pae, int superpages,
+                      uint64_t gid, unsigned long *vm_gid_addr);
 /**
  * xc_domain_restore writes a file to disk that contains the device
  * model saved state.
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xg_save_restore.h
--- a/tools/libxc/xg_save_restore.h	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxc/xg_save_restore.h	Wed Nov 30 20:51:07 2011 +0000
@@ -135,6 +135,7 @@
 #define XC_SAVE_ID_LAST_CHECKPOINT    -9 /* Commit to restoring after
completion of current iteration. */
 #define XC_SAVE_ID_HVM_ACPI_IOPORTS_LOCATION -10
 #define XC_SAVE_ID_HVM_VIRIDIAN       -11
+#define XC_SAVE_ID_HVM_GENERATION_ID_ADDR -12
 
 /*
 ** We process save/restore/migrate in batches of pages; the below
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_create.c
--- a/tools/libxl/libxl_create.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxl/libxl_create.c	Wed Nov 30 20:51:07 2011 +0000
@@ -101,6 +101,7 @@ int libxl_init_build_info(libxl_ctx *ctx
         b_info->u.hvm.vpt_align = 1;
         b_info->u.hvm.timer_mode = 1;
         b_info->u.hvm.nested_hvm = 0;
+        b_info->u.hvm.generation_id = 0;
         break;
     case LIBXL_DOMAIN_TYPE_PV:
         b_info->u.pv.slack_memkb = 8 * 1024;
@@ -191,13 +192,15 @@ int libxl__domain_build(libxl__gc *gc,
         vments[4] = "start_time";
         vments[5] = libxl__sprintf(gc, "%lu.%02d",
start_time.tv_sec,(int)start_time.tv_usec/10000);
 
-        localents = libxl__calloc(gc, 7, sizeof(char *));
+        localents = libxl__calloc(gc, 9, sizeof(char *));
         localents[0] = "platform/acpi";
         localents[1] = (info->u.hvm.acpi) ? "1" : "0";
         localents[2] = "platform/acpi_s3";
         localents[3] = (info->u.hvm.acpi_s3) ? "1" :
"0";
         localents[4] = "platform/acpi_s4";
         localents[5] = (info->u.hvm.acpi_s4) ? "1" :
"0";
+        localents[6] = "platform/generation_id";
+        localents[7] = libxl__sprintf(gc, "0x%llx",
info->u.hvm.generation_id);
 
         break;
     case LIBXL_DOMAIN_TYPE_PV:
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_dom.c
--- a/tools/libxl/libxl_dom.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxl/libxl_dom.c	Wed Nov 30 20:51:07 2011 +0000
@@ -125,7 +125,7 @@ int libxl__build_post(libxl__gc *gc, uin
     if (info->cpuid != NULL)
         libxl_cpuid_set(ctx, domid, info->cpuid);
 
-    ents = libxl__calloc(gc, 12 + (info->max_vcpus * 2) + 2, sizeof(char
*));
+    ents = libxl__calloc(gc, 14 + (info->max_vcpus * 2) + 2, sizeof(char
*));
     ents[0] = "memory/static-max";
     ents[1] = libxl__sprintf(gc, "%d", info->max_memkb);
     ents[2] = "memory/target";
@@ -138,9 +138,11 @@ int libxl__build_post(libxl__gc *gc, uin
     ents[9] = libxl__sprintf(gc, "%"PRIu32, state->store_port);
     ents[10] = "store/ring-ref";
     ents[11] = libxl__sprintf(gc, "%lu", state->store_mfn);
+    ents[12] = "data/generation-id";
+    ents[13] = libxl__sprintf(gc, "0x%lx", state->vm_gid_addr);
     for (i = 0; i < info->max_vcpus; i++) {
-        ents[12+(i*2)]   = libxl__sprintf(gc, "cpu/%d/availability",
i);
-        ents[12+(i*2)+1] = (i && info->cur_vcpus &&
!(info->cur_vcpus & (1 << i)))
+        ents[14+(i*2)]   = libxl__sprintf(gc, "cpu/%d/availability",
i);
+        ents[14+(i*2)+1] = (i && info->cur_vcpus &&
!(info->cur_vcpus & (1 << i)))
                             ? "offline" : "online";
     }
 
@@ -357,16 +359,19 @@ int libxl__domain_restore_common(libxl__
     /* read signature */
     int rc;
     int hvm, pae, superpages;
+    uint64_t gid;
     switch (info->type) {
     case LIBXL_DOMAIN_TYPE_HVM:
         hvm = 1;
         superpages = 1;
         pae = info->u.hvm.pae;
+        gid = info->u.hvm.generation_id;
         break;
     case LIBXL_DOMAIN_TYPE_PV:
         hvm = 0;
         superpages = 0;
         pae = 1;
+        gid = 0;
         break;
     default:
         return ERROR_INVAL;
@@ -374,7 +379,7 @@ int libxl__domain_restore_common(libxl__
     rc = xc_domain_restore(ctx->xch, fd, domid,
                            state->store_port, &state->store_mfn,
                            state->console_port, &state->console_mfn,
-                           hvm, pae, superpages);
+                           hvm, pae, superpages, gid,
&state->vm_gid_addr);
     if ( rc ) {
         LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "restoring domain");
         return ERROR_FAIL;
@@ -540,12 +545,22 @@ int libxl__domain_suspend_common(libxl__
     struct save_callbacks callbacks;
     struct suspendinfo si;
     int hvm, rc = ERROR_FAIL;
+    unsigned long vm_gid_addr;
 
     switch (type) {
-    case LIBXL_DOMAIN_TYPE_HVM:
+    case LIBXL_DOMAIN_TYPE_HVM: {
+        char *path;
+        char *addr;
+
+        path = libxl__sprintf(gc, "%s/data/generation-id",
libxl__xs_get_dompath(gc, domid));
+        addr = libxl__xs_read(gc, XBT_NULL, path);
+
+        vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
         hvm = 1;
         break;
+    }
     case LIBXL_DOMAIN_TYPE_PV:
+        vm_gid_addr = 0;
         hvm = 0;
         break;
     default:
@@ -583,7 +598,8 @@ int libxl__domain_suspend_common(libxl__
     callbacks.switch_qemu_logdirty =
libxl__domain_suspend_common_switch_qemu_logdirty;
     callbacks.data = &si;
 
-    rc = xc_domain_save(ctx->xch, fd, domid, 0, 0, flags, &callbacks,
hvm);
+    rc = xc_domain_save(ctx->xch, fd, domid, 0, 0, flags, &callbacks,
+                        hvm, vm_gid_addr);
     if ( rc ) {
         LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "saving domain: %s",
                          si.guest_responded ?
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_internal.h
--- a/tools/libxl/libxl_internal.h	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxl/libxl_internal.h	Wed Nov 30 20:51:07 2011 +0000
@@ -199,6 +199,8 @@ typedef struct {
 
     uint32_t console_port;
     unsigned long console_mfn;
+
+    unsigned long vm_gid_addr;
 } libxl__domain_build_state;
 
 _hidden int libxl__build_pre(libxl__gc *gc, uint32_t domid,
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_types.idl
--- a/tools/libxl/libxl_types.idl	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxl/libxl_types.idl	Wed Nov 30 20:51:07 2011 +0000
@@ -183,6 +183,7 @@ libxl_domain_build_info = Struct("domain
                                        ("vpt_align", bool),
                                        ("timer_mode", integer),
                                        ("nested_hvm", bool),
+                                       ("generation_id", uint64),
                                        ])),
                  ("pv", Struct(None, [("kernel",
libxl_file_reference),
                                       ("slack_memkb", uint32),
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxlu_cfg.c
--- a/tools/libxl/libxlu_cfg.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxl/libxlu_cfg.c	Wed Nov 30 20:51:07 2011 +0000
@@ -235,6 +235,37 @@ int xlu_cfg_get_long(const XLU_Config *c
     return 0;
 }
 
+int xlu_cfg_get_long_long(const XLU_Config *cfg, const char *n,
+                          long long *value_r, int dont_warn) {
+    long long ll;
+    XLU_ConfigSetting *set;
+    int e;
+    char *ep;
+
+    e= find_atom(cfg,n,&set,dont_warn);  if (e) return e;
+    errno= 0; ll= strtoll(set->values[0], &ep, 0);
+    e= errno;
+    if (errno) {
+        e= errno;
+        assert(e==EINVAL || e==ERANGE);
+        if (!dont_warn)
+            fprintf(cfg->report,
+                    "%s:%d: warning: parameter `%s'' could not be
parsed"
+                    " as a number: %s\n",
+                    cfg->filename, set->lineno, n, strerror(e));
+        return e;
+    }
+    if (*ep || ep==set->values[0]) {
+        if (!dont_warn)
+            fprintf(cfg->report,
+                    "%s:%d: warning: parameter `%s'' is not a
valid number\n",
+                    cfg->filename, set->lineno, n);
+        return EINVAL;
+    }
+    *value_r= ll;
+    return 0;
+}
+
 
 int xlu_cfg_get_list(const XLU_Config *cfg, const char *n,
                      XLU_ConfigList **list_r, int *entries_r, int dont_warn) {
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxlutil.h
--- a/tools/libxl/libxlutil.h	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxl/libxlutil.h	Wed Nov 30 20:51:07 2011 +0000
@@ -52,6 +52,8 @@ int xlu_cfg_replace_string(const XLU_Con
                            char **value_r, int dont_warn);
 int xlu_cfg_get_long(const XLU_Config*, const char *n, long *value_r,
                      int dont_warn);
+int xlu_cfg_get_long_long(const XLU_Config*, const char *n, long long *value_r,
+                          int dont_warn);
 
 int xlu_cfg_get_list(const XLU_Config*, const char *n,
                      XLU_ConfigList **list_r /* may be 0 */,
diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/libxl/xl_cmdimpl.c	Wed Nov 30 20:51:07 2011 +0000
@@ -573,6 +573,7 @@ static void parse_config_data(const char
 {
     const char *buf;
     long l;
+    long long ll;
     XLU_Config *config;
     XLU_ConfigList *vbds, *nics, *pcis, *cvfbs, *cpuids;
     int pci_power_mgmt = 0;
@@ -764,6 +765,8 @@ static void parse_config_data(const char
             b_info->u.hvm.timer_mode = l;
         if (!xlu_cfg_get_long (config, "nestedhvm", &l, 0))
             b_info->u.hvm.nested_hvm = l;
+        if (!xlu_cfg_get_long_long (config, "generation_id", &ll,
0))
+            b_info->u.hvm.nested_hvm = ll;
         break;
     case LIBXL_DOMAIN_TYPE_PV:
     {
diff -r 3c4c29899d8a -r 94a17182f386
tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
--- a/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c	Wed Nov 30 07:18:11
2011 -0800
+++ b/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c	Wed Nov 30 20:51:07
2011 +0000
@@ -174,6 +174,7 @@ int checkpoint_start(checkpoint_state* s
 {
     int hvm, rc;
     int flags = XCFLAGS_LIVE;
+    unsigned long vm_gid_addr;
 
     if (!s->domid) {
        s->errstr = "checkpoint state not opened";
@@ -184,14 +185,25 @@ int checkpoint_start(checkpoint_state* s
 
     hvm = s->domtype > dt_pv;
     if (hvm) {
+       char path[128];
+       char *addr;
+
+       sprintf(path, "/local/domain/%u/data/generation-id",
s->domid);
+       addr = xs_read(s->xsh, XBT_NULL, path, NULL);
+
+       vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
+       free(addr);
+
        flags |= XCFLAGS_HVM;
        if (switch_qemu_logdirty(s, 1))
            return -1;
+    } else {
+       vm_gid_addr = 0;
     }
 
     callbacks->switch_qemu_logdirty = noop_switch_logdirty;
 
-    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags, callbacks,
hvm);
+    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags, callbacks,
hvm, vm_gid_addr);
 
     if (hvm)
        switch_qemu_logdirty(s, 0);
diff -r 3c4c29899d8a -r 94a17182f386 tools/xcutils/xc_restore.c
--- a/tools/xcutils/xc_restore.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/xcutils/xc_restore.c	Wed Nov 30 20:51:07 2011 +0000
@@ -23,7 +23,8 @@ main(int argc, char **argv)
     xc_interface *xch;
     int io_fd, ret;
     int superpages;
-    unsigned long store_mfn, console_mfn;
+    unsigned long store_mfn, console_mfn, vm_gid_addr;
+    uint64_t gid;
 
     if ( (argc != 8) && (argc != 9) )
         errx(1, "usage: %s iofd domid store_evtchn "
@@ -40,19 +41,25 @@ main(int argc, char **argv)
     hvm  = atoi(argv[5]);
     pae  = atoi(argv[6]);
     apic = atoi(argv[7]);
-    if ( argc == 9 )
+    if ( argc >= 9 )
 	    superpages = atoi(argv[8]);
     else
 	    superpages = !!hvm;
+    if ( argc >= 10 )
+	    gid = strtoll(argv[9], NULL, 0);
+    else
+	    gid = 0;
 
     ret = xc_domain_restore(xch, io_fd, domid, store_evtchn, &store_mfn,
-                            console_evtchn, &console_mfn, hvm, pae,
superpages);
+                            console_evtchn, &console_mfn, hvm, pae,
superpages,
+                            gid, &vm_gid_addr);
 
     if ( ret == 0 )
     {
 	printf("store-mfn %li\n", store_mfn);
         if ( !hvm )
             printf("console-mfn %li\n", console_mfn);
+	printf("vm-gid-addr %lx\n", vm_gid_addr);
 	fflush(stdout);
     }
 
diff -r 3c4c29899d8a -r 94a17182f386 tools/xcutils/xc_save.c
--- a/tools/xcutils/xc_save.c	Wed Nov 30 07:18:11 2011 -0800
+++ b/tools/xcutils/xc_save.c	Wed Nov 30 20:51:07 2011 +0000
@@ -169,6 +169,10 @@ main(int argc, char **argv)
     unsigned int maxit, max_f;
     int io_fd, ret, port;
     struct save_callbacks callbacks;
+    char path[128];
+    struct xs_handle *xs;
+    char *addr;
+    unsigned long vm_gid_addr;
 
     if (argc != 6)
         errx(1, "usage: %s iofd domid maxit maxf flags", argv[0]);
@@ -207,8 +211,21 @@ main(int argc, char **argv)
     memset(&callbacks, 0, sizeof(callbacks));
     callbacks.suspend = suspend;
     callbacks.switch_qemu_logdirty = switch_qemu_logdirty;
+
+    sprintf(path, "/local/domain/%d/data/generation-id", si.domid);
+
+    if ((xs = xs_daemon_open()) == NULL)
+        errx(1, "Couldn''t contact xenstore");
+
+    addr = xs_read(xs, XBT_NULL, path, NULL);
+
+    xs_daemon_close(xs);
+
+    vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
+    free(addr);
+
     ret = xc_domain_save(si.xch, io_fd, si.domid, maxit, max_f, si.flags, 
-                         &callbacks, !!(si.flags & XCFLAGS_HVM));
+                         &callbacks, !!(si.flags & XCFLAGS_HVM),
vm_gid_addr);
 
     if (si.suspend_evtchn > 0)
 	 xc_suspend_evtchn_release(si.xch, si.xce, si.domid, si.suspend_evtchn);

On Wed, Nov 30, 2011 at 08:58:37PM +0000, Paul Durrant
wrote:
> # HG changeset patch
> # User Paul Durrant <paul.durrant@citrix.com>
> # Date 1322686267 0
> # Node ID 94a17182f386c8bb414eba55dddf763b8982c76d
> # Parent  3c4c29899d8a2a0c0f9109b7236da95bb72b77b6
> Add code to track the address of the VM generation id buffer across a
> save/restore or migrate and inject a new value.
So what is a generation id? What is the use-case for this?
> The address of the buffer is written into xenstore by hvmloader at
> boot time. It must be read from xenstore by the caller of
> xc_domain_save() and then written back again by the caller of
> xc_domain_restore().
> 
> Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> 
> diff -r 3c4c29899d8a -r 94a17182f386
tools/libxc/ia64/xc_ia64_linux_restore.c
> --- a/tools/libxc/ia64/xc_ia64_linux_restore.c	Wed Nov 30 07:18:11 2011
-0800
> +++ b/tools/libxc/ia64/xc_ia64_linux_restore.c	Wed Nov 30 20:51:07 2011
+0000
> @@ -548,7 +548,8 @@ int
>  xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
>                    unsigned int store_evtchn, unsigned long *store_mfn,
>                    unsigned int console_evtchn, unsigned long *console_mfn,
> -                  unsigned int hvm, unsigned int pae, int superpages)
> +                  unsigned int hvm, unsigned int pae, int superpages,
> +                  uint64_t gid)
>  {
>      DECLARE_DOMCTL;
>      int rc = 1;
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/ia64/xc_ia64_linux_save.c
> --- a/tools/libxc/ia64/xc_ia64_linux_save.c	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxc/ia64/xc_ia64_linux_save.c	Wed Nov 30 20:51:07 2011 +0000
> @@ -382,7 +382,8 @@ out:
>  int
>  xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t
max_iters,
>                 uint32_t max_factor, uint32_t flags,
> -               struct save_callbacks* callbacks, int hvm)
> +               struct save_callbacks* callbacks, int hvm,
> +               unsigned long vm_gid_addr)
>  {
>      DECLARE_DOMCTL;
>      xc_dominfo_t info;
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xc_domain_restore.c
> --- a/tools/libxc/xc_domain_restore.c	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxc/xc_domain_restore.c	Wed Nov 30 20:51:07 2011 +0000
> @@ -676,6 +676,7 @@ typedef struct {
>      uint64_t console_pfn;
>      uint64_t acpi_ioport_location;
>      uint64_t viridian;
> +    uint64_t vm_gid_addr;
>  } pagebuf_t;
>  
>  static int pagebuf_init(pagebuf_t* buf)
> @@ -820,6 +821,17 @@ static int pagebuf_get_one(xc_interface 
>          }
>          return pagebuf_get_one(xch, ctx, buf, fd, dom);
>  
> +    case XC_SAVE_ID_HVM_GENERATION_ID_ADDR:
> +        /* Skip padding 4 bytes then read the generation id buffer
location. */
> +        if ( RDEXACT(fd, &buf->vm_gid_addr, sizeof(uint32_t)) ||
> +             RDEXACT(fd, &buf->vm_gid_addr, sizeof(uint64_t)) )
> +        {
> +            PERROR("error read the generation id buffer
location");
> +            return -1;
> +        }
> +        DPRINTF("read generation id buffer address");
> +        return pagebuf_get_one(xch, ctx, buf, fd, dom);
> +
>      default:
>          if ( (count > MAX_BATCH_SIZE) || (count < 0) ) {
>              ERROR("Max batch size exceeded (%d). Giving up.",
count);
> @@ -1186,7 +1198,8 @@ static int apply_batch(xc_interface *xch
>  int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
>                        unsigned int store_evtchn, unsigned long *store_mfn,
>                        unsigned int console_evtchn, unsigned long
*console_mfn,
> -                      unsigned int hvm, unsigned int pae, int superpages)
> +                      unsigned int hvm, unsigned int pae, int superpages,
> +                      uint64_t gid, unsigned long *vm_gid_addr)
>  {
>      DECLARE_DOMCTL;
>      int rc = 1, frc, i, j, n, m, pae_extended_cr3 = 0, ext_vcpucontext =
0;
> @@ -1386,6 +1399,33 @@ int xc_domain_restore(xc_interface *xch,
>                  xc_set_hvm_param(xch, dom, HVM_PARAM_VM86_TSS,
pagebuf.vm86_tss);
>              if ( pagebuf.console_pfn )
>                  console_pfn = pagebuf.console_pfn;
> +            if ( pagebuf.vm_gid_addr ) {
> +                unsigned int offset;
> +                unsigned char *buf;
> +
> +                /*
> +                 * Map the VM generation id buffer and inject the new
value.
> +                 */
> +
> +                pfn = pagebuf.vm_gid_addr >> PAGE_SHIFT;
> +                offset = pagebuf.vm_gid_addr & (PAGE_SIZE - 1);
> +            
> +                if ( (pfn >= dinfo->p2m_size) ||
> +                     (pfn_type[pfn] != XEN_DOMCTL_PFINFO_NOTAB) )
> +                {
> +                    ERROR("generation id buffer frame is bad");
> +                    goto out;
> +                }
> +
> +                mfn = ctx->p2m[pfn];
> +                buf = xc_map_foreign_range(xch, dom, PAGE_SIZE,
> +                                           PROT_READ | PROT_WRITE, mfn);
> +                *(unsigned long long *)(buf + offset) = gid;
> +                munmap(buf, PAGE_SIZE);
> +
> +                *vm_gid_addr = pagebuf.vm_gid_addr;
> +            }
> +
>              break;  /* our work here is done */
>          }
>  
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xc_domain_save.c
> --- a/tools/libxc/xc_domain_save.c	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxc/xc_domain_save.c	Wed Nov 30 20:51:07 2011 +0000
> @@ -754,7 +754,8 @@ static int save_tsc_info(xc_interface *x
>  
>  int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t
max_iters,
>                     uint32_t max_factor, uint32_t flags,
> -                   struct save_callbacks* callbacks, int hvm)
> +                   struct save_callbacks* callbacks, int hvm,
> +                   unsigned long vm_gid_addr)
>  {
>      xc_dominfo_t info;
>      DECLARE_DOMCTL;
> @@ -1460,6 +1461,16 @@ int xc_domain_save(xc_interface *xch, in
>              uint64_t data;
>          } chunk = { 0, };
>  
> +        chunk.id = XC_SAVE_ID_HVM_GENERATION_ID_ADDR;
> +        chunk.data = vm_gid_addr;
> +
> +        if ( (chunk.data != 0) &&
> +             wrexact(io_fd, &chunk, sizeof(chunk)) )
> +        {
> +            PERROR("Error when writing the generation id buffer
location for guest");
> +            goto out;
> +        }
> +
>          chunk.id = XC_SAVE_ID_HVM_IDENT_PT;
>          chunk.data = 0;
>          xc_get_hvm_param(xch, dom, HVM_PARAM_IDENT_PT,
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xenguest.h
> --- a/tools/libxc/xenguest.h	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxc/xenguest.h	Wed Nov 30 20:51:07 2011 +0000
> @@ -57,7 +57,8 @@ struct save_callbacks {
>   */
>  int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t
max_iters,
>                     uint32_t max_factor, uint32_t flags /* XCFLAGS_xxx */,
> -                   struct save_callbacks* callbacks, int hvm);
> +                   struct save_callbacks* callbacks, int hvm,
> +                   unsigned long vm_gid_addr);
>  
>  
>  /**
> @@ -71,12 +72,15 @@ int xc_domain_save(xc_interface *xch, in
>   * @parm hvm non-zero if this is a HVM restore
>   * @parm pae non-zero if this HVM domain has PAE support enabled
>   * @parm superpages non-zero to allocate guest memory with superpages
> + * @parm gid the new generation id of the VM
> + * @parm vm_gid_addr returned with the address of the generation id buffer
>   * @return 0 on success, -1 on failure
>   */
>  int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
>                        unsigned int store_evtchn, unsigned long *store_mfn,
>                        unsigned int console_evtchn, unsigned long
*console_mfn,
> -                      unsigned int hvm, unsigned int pae, int superpages);
> +                      unsigned int hvm, unsigned int pae, int superpages,
> +                      uint64_t gid, unsigned long *vm_gid_addr);
>  /**
>   * xc_domain_restore writes a file to disk that contains the device
>   * model saved state.
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xg_save_restore.h
> --- a/tools/libxc/xg_save_restore.h	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxc/xg_save_restore.h	Wed Nov 30 20:51:07 2011 +0000
> @@ -135,6 +135,7 @@
>  #define XC_SAVE_ID_LAST_CHECKPOINT    -9 /* Commit to restoring after
completion of current iteration. */
>  #define XC_SAVE_ID_HVM_ACPI_IOPORTS_LOCATION -10
>  #define XC_SAVE_ID_HVM_VIRIDIAN       -11
> +#define XC_SAVE_ID_HVM_GENERATION_ID_ADDR -12
>  
>  /*
>  ** We process save/restore/migrate in batches of pages; the below
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_create.c
> --- a/tools/libxl/libxl_create.c	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/libxl_create.c	Wed Nov 30 20:51:07 2011 +0000
> @@ -101,6 +101,7 @@ int libxl_init_build_info(libxl_ctx *ctx
>          b_info->u.hvm.vpt_align = 1;
>          b_info->u.hvm.timer_mode = 1;
>          b_info->u.hvm.nested_hvm = 0;
> +        b_info->u.hvm.generation_id = 0;
>          break;
>      case LIBXL_DOMAIN_TYPE_PV:
>          b_info->u.pv.slack_memkb = 8 * 1024;
> @@ -191,13 +192,15 @@ int libxl__domain_build(libxl__gc *gc,
>          vments[4] = "start_time";
>          vments[5] = libxl__sprintf(gc, "%lu.%02d",
start_time.tv_sec,(int)start_time.tv_usec/10000);
>  
> -        localents = libxl__calloc(gc, 7, sizeof(char *));
> +        localents = libxl__calloc(gc, 9, sizeof(char *));
>          localents[0] = "platform/acpi";
>          localents[1] = (info->u.hvm.acpi) ? "1" :
"0";
>          localents[2] = "platform/acpi_s3";
>          localents[3] = (info->u.hvm.acpi_s3) ? "1" :
"0";
>          localents[4] = "platform/acpi_s4";
>          localents[5] = (info->u.hvm.acpi_s4) ? "1" :
"0";
> +        localents[6] = "platform/generation_id";
> +        localents[7] = libxl__sprintf(gc, "0x%llx",
info->u.hvm.generation_id);
>  
>          break;
>      case LIBXL_DOMAIN_TYPE_PV:
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_dom.c
> --- a/tools/libxl/libxl_dom.c	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/libxl_dom.c	Wed Nov 30 20:51:07 2011 +0000
> @@ -125,7 +125,7 @@ int libxl__build_post(libxl__gc *gc, uin
>      if (info->cpuid != NULL)
>          libxl_cpuid_set(ctx, domid, info->cpuid);
>  
> -    ents = libxl__calloc(gc, 12 + (info->max_vcpus * 2) + 2,
sizeof(char *));
> +    ents = libxl__calloc(gc, 14 + (info->max_vcpus * 2) + 2,
sizeof(char *));
>      ents[0] = "memory/static-max";
>      ents[1] = libxl__sprintf(gc, "%d", info->max_memkb);
>      ents[2] = "memory/target";
> @@ -138,9 +138,11 @@ int libxl__build_post(libxl__gc *gc, uin
>      ents[9] = libxl__sprintf(gc, "%"PRIu32,
state->store_port);
>      ents[10] = "store/ring-ref";
>      ents[11] = libxl__sprintf(gc, "%lu", state->store_mfn);
> +    ents[12] = "data/generation-id";
> +    ents[13] = libxl__sprintf(gc, "0x%lx",
state->vm_gid_addr);
>      for (i = 0; i < info->max_vcpus; i++) {
> -        ents[12+(i*2)]   = libxl__sprintf(gc,
"cpu/%d/availability", i);
> -        ents[12+(i*2)+1] = (i && info->cur_vcpus &&
!(info->cur_vcpus & (1 << i)))
> +        ents[14+(i*2)]   = libxl__sprintf(gc,
"cpu/%d/availability", i);
> +        ents[14+(i*2)+1] = (i && info->cur_vcpus &&
!(info->cur_vcpus & (1 << i)))
>                              ? "offline" : "online";
>      }
>  
> @@ -357,16 +359,19 @@ int libxl__domain_restore_common(libxl__
>      /* read signature */
>      int rc;
>      int hvm, pae, superpages;
> +    uint64_t gid;
>      switch (info->type) {
>      case LIBXL_DOMAIN_TYPE_HVM:
>          hvm = 1;
>          superpages = 1;
>          pae = info->u.hvm.pae;
> +        gid = info->u.hvm.generation_id;
>          break;
>      case LIBXL_DOMAIN_TYPE_PV:
>          hvm = 0;
>          superpages = 0;
>          pae = 1;
> +        gid = 0;
>          break;
>      default:
>          return ERROR_INVAL;
> @@ -374,7 +379,7 @@ int libxl__domain_restore_common(libxl__
>      rc = xc_domain_restore(ctx->xch, fd, domid,
>                             state->store_port, &state->store_mfn,
>                             state->console_port,
&state->console_mfn,
> -                           hvm, pae, superpages);
> +                           hvm, pae, superpages, gid,
&state->vm_gid_addr);
>      if ( rc ) {
>          LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "restoring
domain");
>          return ERROR_FAIL;
> @@ -540,12 +545,22 @@ int libxl__domain_suspend_common(libxl__
>      struct save_callbacks callbacks;
>      struct suspendinfo si;
>      int hvm, rc = ERROR_FAIL;
> +    unsigned long vm_gid_addr;
>  
>      switch (type) {
> -    case LIBXL_DOMAIN_TYPE_HVM:
> +    case LIBXL_DOMAIN_TYPE_HVM: {
> +        char *path;
> +        char *addr;
> +
> +        path = libxl__sprintf(gc, "%s/data/generation-id",
libxl__xs_get_dompath(gc, domid));
> +        addr = libxl__xs_read(gc, XBT_NULL, path);
> +
> +        vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
>          hvm = 1;
>          break;
> +    }
>      case LIBXL_DOMAIN_TYPE_PV:
> +        vm_gid_addr = 0;
>          hvm = 0;
>          break;
>      default:
> @@ -583,7 +598,8 @@ int libxl__domain_suspend_common(libxl__
>      callbacks.switch_qemu_logdirty =
libxl__domain_suspend_common_switch_qemu_logdirty;
>      callbacks.data = &si;
>  
> -    rc = xc_domain_save(ctx->xch, fd, domid, 0, 0, flags,
&callbacks, hvm);
> +    rc = xc_domain_save(ctx->xch, fd, domid, 0, 0, flags,
&callbacks,
> +                        hvm, vm_gid_addr);
>      if ( rc ) {
>          LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "saving domain:
%s",
>                           si.guest_responded ?
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_internal.h
> --- a/tools/libxl/libxl_internal.h	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/libxl_internal.h	Wed Nov 30 20:51:07 2011 +0000
> @@ -199,6 +199,8 @@ typedef struct {
>  
>      uint32_t console_port;
>      unsigned long console_mfn;
> +
> +    unsigned long vm_gid_addr;
>  } libxl__domain_build_state;
>  
>  _hidden int libxl__build_pre(libxl__gc *gc, uint32_t domid,
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_types.idl
> --- a/tools/libxl/libxl_types.idl	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/libxl_types.idl	Wed Nov 30 20:51:07 2011 +0000
> @@ -183,6 +183,7 @@ libxl_domain_build_info = Struct("domain
>                                         ("vpt_align", bool),
>                                         ("timer_mode", integer),
>                                         ("nested_hvm", bool),
> +                                       ("generation_id",
uint64),
>                                         ])),
>                   ("pv", Struct(None, [("kernel",
libxl_file_reference),
>                                        ("slack_memkb", uint32),
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxlu_cfg.c
> --- a/tools/libxl/libxlu_cfg.c	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/libxlu_cfg.c	Wed Nov 30 20:51:07 2011 +0000
> @@ -235,6 +235,37 @@ int xlu_cfg_get_long(const XLU_Config *c
>      return 0;
>  }
>  
> +int xlu_cfg_get_long_long(const XLU_Config *cfg, const char *n,
> +                          long long *value_r, int dont_warn) {
> +    long long ll;
> +    XLU_ConfigSetting *set;
> +    int e;
> +    char *ep;
> +
> +    e= find_atom(cfg,n,&set,dont_warn);  if (e) return e;
> +    errno= 0; ll= strtoll(set->values[0], &ep, 0);
> +    e= errno;
> +    if (errno) {
> +        e= errno;
> +        assert(e==EINVAL || e==ERANGE);
> +        if (!dont_warn)
> +            fprintf(cfg->report,
> +                    "%s:%d: warning: parameter `%s'' could
not be parsed"
> +                    " as a number: %s\n",
> +                    cfg->filename, set->lineno, n, strerror(e));
> +        return e;
> +    }
> +    if (*ep || ep==set->values[0]) {
> +        if (!dont_warn)
> +            fprintf(cfg->report,
> +                    "%s:%d: warning: parameter `%s'' is not a
valid number\n",
> +                    cfg->filename, set->lineno, n);
> +        return EINVAL;
> +    }
> +    *value_r= ll;
> +    return 0;
> +}
> +
>  
>  int xlu_cfg_get_list(const XLU_Config *cfg, const char *n,
>                       XLU_ConfigList **list_r, int *entries_r, int
dont_warn) {
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxlutil.h
> --- a/tools/libxl/libxlutil.h	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/libxlutil.h	Wed Nov 30 20:51:07 2011 +0000
> @@ -52,6 +52,8 @@ int xlu_cfg_replace_string(const XLU_Con
>                             char **value_r, int dont_warn);
>  int xlu_cfg_get_long(const XLU_Config*, const char *n, long *value_r,
>                       int dont_warn);
> +int xlu_cfg_get_long_long(const XLU_Config*, const char *n, long long
*value_r,
> +                          int dont_warn);
>  
>  int xlu_cfg_get_list(const XLU_Config*, const char *n,
>                       XLU_ConfigList **list_r /* may be 0 */,
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/xl_cmdimpl.c
> --- a/tools/libxl/xl_cmdimpl.c	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/xl_cmdimpl.c	Wed Nov 30 20:51:07 2011 +0000
> @@ -573,6 +573,7 @@ static void parse_config_data(const char
>  {
>      const char *buf;
>      long l;
> +    long long ll;
>      XLU_Config *config;
>      XLU_ConfigList *vbds, *nics, *pcis, *cvfbs, *cpuids;
>      int pci_power_mgmt = 0;
> @@ -764,6 +765,8 @@ static void parse_config_data(const char
>              b_info->u.hvm.timer_mode = l;
>          if (!xlu_cfg_get_long (config, "nestedhvm", &l, 0))
>              b_info->u.hvm.nested_hvm = l;
> +        if (!xlu_cfg_get_long_long (config, "generation_id",
&ll, 0))
> +            b_info->u.hvm.nested_hvm = ll;
>          break;
>      case LIBXL_DOMAIN_TYPE_PV:
>      {
> diff -r 3c4c29899d8a -r 94a17182f386
tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
> --- a/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c	Wed Nov 30
07:18:11 2011 -0800
> +++ b/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c	Wed Nov 30
20:51:07 2011 +0000
> @@ -174,6 +174,7 @@ int checkpoint_start(checkpoint_state* s
>  {
>      int hvm, rc;
>      int flags = XCFLAGS_LIVE;
> +    unsigned long vm_gid_addr;
>  
>      if (!s->domid) {
>         s->errstr = "checkpoint state not opened";
> @@ -184,14 +185,25 @@ int checkpoint_start(checkpoint_state* s
>  
>      hvm = s->domtype > dt_pv;
>      if (hvm) {
> +       char path[128];
> +       char *addr;
> +
> +       sprintf(path, "/local/domain/%u/data/generation-id",
s->domid);
> +       addr = xs_read(s->xsh, XBT_NULL, path, NULL);
> +
> +       vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
> +       free(addr);
> +
>         flags |= XCFLAGS_HVM;
>         if (switch_qemu_logdirty(s, 1))
>             return -1;
> +    } else {
> +       vm_gid_addr = 0;
>      }
>  
>      callbacks->switch_qemu_logdirty = noop_switch_logdirty;
>  
> -    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags,
callbacks, hvm);
> +    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags,
callbacks, hvm, vm_gid_addr);
>  
>      if (hvm)
>         switch_qemu_logdirty(s, 0);
> diff -r 3c4c29899d8a -r 94a17182f386 tools/xcutils/xc_restore.c
> --- a/tools/xcutils/xc_restore.c	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/xcutils/xc_restore.c	Wed Nov 30 20:51:07 2011 +0000
> @@ -23,7 +23,8 @@ main(int argc, char **argv)
>      xc_interface *xch;
>      int io_fd, ret;
>      int superpages;
> -    unsigned long store_mfn, console_mfn;
> +    unsigned long store_mfn, console_mfn, vm_gid_addr;
> +    uint64_t gid;
>  
>      if ( (argc != 8) && (argc != 9) )
>          errx(1, "usage: %s iofd domid store_evtchn "
> @@ -40,19 +41,25 @@ main(int argc, char **argv)
>      hvm  = atoi(argv[5]);
>      pae  = atoi(argv[6]);
>      apic = atoi(argv[7]);
> -    if ( argc == 9 )
> +    if ( argc >= 9 )
>  	    superpages = atoi(argv[8]);
>      else
>  	    superpages = !!hvm;
> +    if ( argc >= 10 )
> +	    gid = strtoll(argv[9], NULL, 0);
> +    else
> +	    gid = 0;
>  
>      ret = xc_domain_restore(xch, io_fd, domid, store_evtchn,
&store_mfn,
> -                            console_evtchn, &console_mfn, hvm, pae,
superpages);
> +                            console_evtchn, &console_mfn, hvm, pae,
superpages,
> +                            gid, &vm_gid_addr);
>  
>      if ( ret == 0 )
>      {
>  	printf("store-mfn %li\n", store_mfn);
>          if ( !hvm )
>              printf("console-mfn %li\n", console_mfn);
> +	printf("vm-gid-addr %lx\n", vm_gid_addr);
>  	fflush(stdout);
>      }
>  
> diff -r 3c4c29899d8a -r 94a17182f386 tools/xcutils/xc_save.c
> --- a/tools/xcutils/xc_save.c	Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/xcutils/xc_save.c	Wed Nov 30 20:51:07 2011 +0000
> @@ -169,6 +169,10 @@ main(int argc, char **argv)
>      unsigned int maxit, max_f;
>      int io_fd, ret, port;
>      struct save_callbacks callbacks;
> +    char path[128];
> +    struct xs_handle *xs;
> +    char *addr;
> +    unsigned long vm_gid_addr;
>  
>      if (argc != 6)
>          errx(1, "usage: %s iofd domid maxit maxf flags",
argv[0]);
> @@ -207,8 +211,21 @@ main(int argc, char **argv)
>      memset(&callbacks, 0, sizeof(callbacks));
>      callbacks.suspend = suspend;
>      callbacks.switch_qemu_logdirty = switch_qemu_logdirty;
> +
> +    sprintf(path, "/local/domain/%d/data/generation-id",
si.domid);
> +
> +    if ((xs = xs_daemon_open()) == NULL)
> +        errx(1, "Couldn''t contact xenstore");
> +
> +    addr = xs_read(xs, XBT_NULL, path, NULL);
> +
> +    xs_daemon_close(xs);
> +
> +    vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
> +    free(addr);
> +
>      ret = xc_domain_save(si.xch, io_fd, si.domid, maxit, max_f, si.flags, 
> -                         &callbacks, !!(si.flags & XCFLAGS_HVM));
> +                         &callbacks, !!(si.flags & XCFLAGS_HVM),
vm_gid_addr);
>  
>      if (si.suspend_evtchn > 0)
>  	 xc_suspend_evtchn_release(si.xch, si.xce, si.domid, si.suspend_evtchn);
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

Konrad,

  Did you see my previous patch set? The introductory comment was:

-----
The following is a revised patch series to add support for a VM generation ID
virtual device for HVM guests.
The basic requirements of this device are as follows:

- It must be exposed somewhere in ACPI namespace with a _CID of
  "VM_Gen_Counter".
- It must also include a _DDN of "VM_Gen_Counter".
- It must contain a _HID object but no particular value is
  required.
- It must expose a package called ADDR which evaluates to two
  integers; the first being the low order 32-bits of a guest
  physical address (GPA), the second by the high order 32-bits of
  the GPA. This GPA is the address of an 8-byte aligned 8-byte
  buffer containing the VM generation ID.
  This buffer must not be in ranges supported as AddressRangeMemory
  or AddressRangeACPI and must not be mapped by any PTE with caching
  disabled.

The semantics of the VM generation ID itself are left up to the tools but it
must be possible to change it each time the VM is booted, migrated, or restored
from a saved image.
-----

  Does that help?

    Paul
> -----Original Message-----
> From: Konrad Rzeszutek Wilk [mailto:konrad@darnok.org]
> Sent: 30 November 2011 22:14
> To: Paul Durrant
> Cc: xen-devel@lists.xensource.com
> Subject: Re: [Xen-devel] [PATCH] Add code to track the address of
> the VM generation id buffer across a
>
> On Wed, Nov 30, 2011 at 08:58:37PM +0000, Paul Durrant wrote:
> > # HG changeset patch
> > # User Paul Durrant <paul.durrant@citrix.com> # Date 1322686267
0
> #
> > Node ID 94a17182f386c8bb414eba55dddf763b8982c76d
> > # Parent  3c4c29899d8a2a0c0f9109b7236da95bb72b77b6
> > Add code to track the address of the VM generation id buffer
> across a
> > save/restore or migrate and inject a new value.
>
> So what is a generation id? What is the use-case for this?
>
> > The address of the buffer is written into xenstore by hvmloader at
> > boot time. It must be read from xenstore by the caller of
> > xc_domain_save() and then written back again by the caller of
> > xc_domain_restore().
> >
> > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> >
> > diff -r 3c4c29899d8a -r 94a17182f386
> tools/libxc/ia64/xc_ia64_linux_restore.c
> > --- a/tools/libxc/ia64/xc_ia64_linux_restore.c      Wed Nov 30
> 07:18:11 2011 -0800
> > +++ b/tools/libxc/ia64/xc_ia64_linux_restore.c      Wed Nov 30
> 20:51:07 2011 +0000
> > @@ -548,7 +548,8 @@ int
> >  xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
> >                    unsigned int store_evtchn, unsigned long
> *store_mfn,
> >                    unsigned int console_evtchn, unsigned long
> *console_mfn,
> > -                  unsigned int hvm, unsigned int pae, int
> superpages)
> > +                  unsigned int hvm, unsigned int pae, int
> superpages,
> > +                  uint64_t gid)
> >  {
> >      DECLARE_DOMCTL;
> >      int rc = 1;
> > diff -r 3c4c29899d8a -r 94a17182f386
> tools/libxc/ia64/xc_ia64_linux_save.c
> > --- a/tools/libxc/ia64/xc_ia64_linux_save.c Wed Nov 30 07:18:11
> 2011 -0800
> > +++ b/tools/libxc/ia64/xc_ia64_linux_save.c Wed Nov 30 20:51:07
> 2011 +0000
> > @@ -382,7 +382,8 @@ out:
> >  int
> >  xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom,
> uint32_t max_iters,
> >                 uint32_t max_factor, uint32_t flags,
> > -               struct save_callbacks* callbacks, int hvm)
> > +               struct save_callbacks* callbacks, int hvm,
> > +               unsigned long vm_gid_addr)
> >  {
> >      DECLARE_DOMCTL;
> >      xc_dominfo_t info;
> > diff -r 3c4c29899d8a -r 94a17182f386
> tools/libxc/xc_domain_restore.c
> > --- a/tools/libxc/xc_domain_restore.c       Wed Nov 30 07:18:11 2011 -
> 0800
> > +++ b/tools/libxc/xc_domain_restore.c       Wed Nov 30 20:51:07 2011
> +0000
> > @@ -676,6 +676,7 @@ typedef struct {
> >      uint64_t console_pfn;
> >      uint64_t acpi_ioport_location;
> >      uint64_t viridian;
> > +    uint64_t vm_gid_addr;
> >  } pagebuf_t;
> >
> >  static int pagebuf_init(pagebuf_t* buf) @@ -820,6 +821,17 @@
> static
> > int pagebuf_get_one(xc_interface
> >          }
> >          return pagebuf_get_one(xch, ctx, buf, fd, dom);
> >
> > +    case XC_SAVE_ID_HVM_GENERATION_ID_ADDR:
> > +        /* Skip padding 4 bytes then read the generation id
> buffer location. */
> > +        if ( RDEXACT(fd, &buf->vm_gid_addr, sizeof(uint32_t))
||
> > +             RDEXACT(fd, &buf->vm_gid_addr, sizeof(uint64_t))
)
> > +        {
> > +            PERROR("error read the generation id buffer
> location");
> > +            return -1;
> > +        }
> > +        DPRINTF("read generation id buffer address");
> > +        return pagebuf_get_one(xch, ctx, buf, fd, dom);
> > +
> >      default:
> >          if ( (count > MAX_BATCH_SIZE) || (count < 0) ) {
> >              ERROR("Max batch size exceeded (%d). Giving
up.",
> count);
> > @@ -1186,7 +1198,8 @@ static int apply_batch(xc_interface *xch
> int
> > xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
> >                        unsigned int store_evtchn, unsigned long
> *store_mfn,
> >                        unsigned int console_evtchn, unsigned long
> *console_mfn,
> > -                      unsigned int hvm, unsigned int pae, int
> superpages)
> > +                      unsigned int hvm, unsigned int pae, int
> superpages,
> > +                      uint64_t gid, unsigned long *vm_gid_addr)
> >  {
> >      DECLARE_DOMCTL;
> >      int rc = 1, frc, i, j, n, m, pae_extended_cr3 = 0,
> > ext_vcpucontext = 0; @@ -1386,6 +1399,33 @@ int
> xc_domain_restore(xc_interface *xch,
> >                  xc_set_hvm_param(xch, dom, HVM_PARAM_VM86_TSS,
> pagebuf.vm86_tss);
> >              if ( pagebuf.console_pfn )
> >                  console_pfn = pagebuf.console_pfn;
> > +            if ( pagebuf.vm_gid_addr ) {
> > +                unsigned int offset;
> > +                unsigned char *buf;
> > +
> > +                /*
> > +                 * Map the VM generation id buffer and inject the
> new value.
> > +                 */
> > +
> > +                pfn = pagebuf.vm_gid_addr >> PAGE_SHIFT;
> > +                offset = pagebuf.vm_gid_addr & (PAGE_SIZE - 1);
> > +
> > +                if ( (pfn >= dinfo->p2m_size) ||
> > +                     (pfn_type[pfn] != XEN_DOMCTL_PFINFO_NOTAB) )
> > +                {
> > +                    ERROR("generation id buffer frame is
bad");
> > +                    goto out;
> > +                }
> > +
> > +                mfn = ctx->p2m[pfn];
> > +                buf = xc_map_foreign_range(xch, dom, PAGE_SIZE,
> > +                                           PROT_READ |
> PROT_WRITE, mfn);
> > +                *(unsigned long long *)(buf + offset) = gid;
> > +                munmap(buf, PAGE_SIZE);
> > +
> > +                *vm_gid_addr = pagebuf.vm_gid_addr;
> > +            }
> > +
> >              break;  /* our work here is done */
> >          }
> >
> > diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xc_domain_save.c
> > --- a/tools/libxc/xc_domain_save.c  Wed Nov 30 07:18:11 2011 -
> 0800
> > +++ b/tools/libxc/xc_domain_save.c  Wed Nov 30 20:51:07 2011
> +0000
> > @@ -754,7 +754,8 @@ static int save_tsc_info(xc_interface *x
> >
> >  int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom,
> uint32_t max_iters,
> >                     uint32_t max_factor, uint32_t flags,
> > -                   struct save_callbacks* callbacks, int hvm)
> > +                   struct save_callbacks* callbacks, int hvm,
> > +                   unsigned long vm_gid_addr)
> >  {
> >      xc_dominfo_t info;
> >      DECLARE_DOMCTL;
> > @@ -1460,6 +1461,16 @@ int xc_domain_save(xc_interface *xch, in
> >              uint64_t data;
> >          } chunk = { 0, };
> >
> > +        chunk.id = XC_SAVE_ID_HVM_GENERATION_ID_ADDR;
> > +        chunk.data = vm_gid_addr;
> > +
> > +        if ( (chunk.data != 0) &&
> > +             wrexact(io_fd, &chunk, sizeof(chunk)) )
> > +        {
> > +            PERROR("Error when writing the generation id buffer
> location for guest");
> > +            goto out;
> > +        }
> > +
> >          chunk.id = XC_SAVE_ID_HVM_IDENT_PT;
> >          chunk.data = 0;
> >          xc_get_hvm_param(xch, dom, HVM_PARAM_IDENT_PT, diff -r
> > 3c4c29899d8a -r 94a17182f386 tools/libxc/xenguest.h
> > --- a/tools/libxc/xenguest.h        Wed Nov 30 07:18:11 2011 -0800
> > +++ b/tools/libxc/xenguest.h        Wed Nov 30 20:51:07 2011 +0000
> > @@ -57,7 +57,8 @@ struct save_callbacks {
> >   */
> >  int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom,
> uint32_t max_iters,
> >                     uint32_t max_factor, uint32_t flags /*
> XCFLAGS_xxx */,
> > -                   struct save_callbacks* callbacks, int hvm);
> > +                   struct save_callbacks* callbacks, int hvm,
> > +                   unsigned long vm_gid_addr);
> >
> >
> >  /**
> > @@ -71,12 +72,15 @@ int xc_domain_save(xc_interface *xch, in
> >   * @parm hvm non-zero if this is a HVM restore
> >   * @parm pae non-zero if this HVM domain has PAE support enabled
> >   * @parm superpages non-zero to allocate guest memory with
> superpages
> > + * @parm gid the new generation id of the VM
> > + * @parm vm_gid_addr returned with the address of the generation
> id
> > + buffer
> >   * @return 0 on success, -1 on failure
> >   */
> >  int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
> >                        unsigned int store_evtchn, unsigned long
> *store_mfn,
> >                        unsigned int console_evtchn, unsigned long
> *console_mfn,
> > -                      unsigned int hvm, unsigned int pae, int
> superpages);
> > +                      unsigned int hvm, unsigned int pae, int
> superpages,
> > +                      uint64_t gid, unsigned long *vm_gid_addr);
> >  /**
> >   * xc_domain_restore writes a file to disk that contains the
> device
> >   * model saved state.
> > diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xg_save_restore.h
> > --- a/tools/libxc/xg_save_restore.h Wed Nov 30 07:18:11 2011 -
> 0800
> > +++ b/tools/libxc/xg_save_restore.h Wed Nov 30 20:51:07 2011
> +0000
> > @@ -135,6 +135,7 @@
> >  #define XC_SAVE_ID_LAST_CHECKPOINT    -9 /* Commit to restoring
> after completion of current iteration. */
> >  #define XC_SAVE_ID_HVM_ACPI_IOPORTS_LOCATION -10
> >  #define XC_SAVE_ID_HVM_VIRIDIAN       -11
> > +#define XC_SAVE_ID_HVM_GENERATION_ID_ADDR -12
> >
> >  /*
> >  ** We process save/restore/migrate in batches of pages; the below
> > diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_create.c
> > --- a/tools/libxl/libxl_create.c    Wed Nov 30 07:18:11 2011 -0800
> > +++ b/tools/libxl/libxl_create.c    Wed Nov 30 20:51:07 2011 +0000
> > @@ -101,6 +101,7 @@ int libxl_init_build_info(libxl_ctx *ctx
> >          b_info->u.hvm.vpt_align = 1;
> >          b_info->u.hvm.timer_mode = 1;
> >          b_info->u.hvm.nested_hvm = 0;
> > +        b_info->u.hvm.generation_id = 0;
> >          break;
> >      case LIBXL_DOMAIN_TYPE_PV:
> >          b_info->u.pv.slack_memkb = 8 * 1024; @@ -191,13 +192,15
> @@
> > int libxl__domain_build(libxl__gc *gc,
> >          vments[4] = "start_time";
> >          vments[5] = libxl__sprintf(gc, "%lu.%02d",
> > start_time.tv_sec,(int)start_time.tv_usec/10000);
> >
> > -        localents = libxl__calloc(gc, 7, sizeof(char *));
> > +        localents = libxl__calloc(gc, 9, sizeof(char *));
> >          localents[0] = "platform/acpi";
> >          localents[1] = (info->u.hvm.acpi) ? "1" :
"0";
> >          localents[2] = "platform/acpi_s3";
> >          localents[3] = (info->u.hvm.acpi_s3) ? "1" :
"0";
> >          localents[4] = "platform/acpi_s4";
> >          localents[5] = (info->u.hvm.acpi_s4) ? "1" :
"0";
> > +        localents[6] = "platform/generation_id";
> > +        localents[7] = libxl__sprintf(gc, "0x%llx",
> > + info->u.hvm.generation_id);
> >
> >          break;
> >      case LIBXL_DOMAIN_TYPE_PV:
> > diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_dom.c
> > --- a/tools/libxl/libxl_dom.c       Wed Nov 30 07:18:11 2011 -0800
> > +++ b/tools/libxl/libxl_dom.c       Wed Nov 30 20:51:07 2011 +0000
> > @@ -125,7 +125,7 @@ int libxl__build_post(libxl__gc *gc, uin
> >      if (info->cpuid != NULL)
> >          libxl_cpuid_set(ctx, domid, info->cpuid);
> >
> > -    ents = libxl__calloc(gc, 12 + (info->max_vcpus * 2) + 2,
> sizeof(char *));
> > +    ents = libxl__calloc(gc, 14 + (info->max_vcpus * 2) + 2,
> > + sizeof(char *));
> >      ents[0] = "memory/static-max";
> >      ents[1] = libxl__sprintf(gc, "%d", info->max_memkb);
> >      ents[2] = "memory/target";
> > @@ -138,9 +138,11 @@ int libxl__build_post(libxl__gc *gc, uin
> >      ents[9] = libxl__sprintf(gc, "%"PRIu32,
state->store_port);
> >      ents[10] = "store/ring-ref";
> >      ents[11] = libxl__sprintf(gc, "%lu",
state->store_mfn);
> > +    ents[12] = "data/generation-id";
> > +    ents[13] = libxl__sprintf(gc, "0x%lx",
state->vm_gid_addr);
> >      for (i = 0; i < info->max_vcpus; i++) {
> > -        ents[12+(i*2)]   = libxl__sprintf(gc,
> "cpu/%d/availability", i);
> > -        ents[12+(i*2)+1] = (i && info->cur_vcpus
&& !(info-
> >cur_vcpus & (1 << i)))
> > +        ents[14+(i*2)]   = libxl__sprintf(gc,
> "cpu/%d/availability", i);
> > +        ents[14+(i*2)+1] = (i && info->cur_vcpus
&& !(info-
> >cur_vcpus
> > + & (1 << i)))
> >                              ? "offline" :
"online";
> >      }
> >
> > @@ -357,16 +359,19 @@ int libxl__domain_restore_common(libxl__
> >      /* read signature */
> >      int rc;
> >      int hvm, pae, superpages;
> > +    uint64_t gid;
> >      switch (info->type) {
> >      case LIBXL_DOMAIN_TYPE_HVM:
> >          hvm = 1;
> >          superpages = 1;
> >          pae = info->u.hvm.pae;
> > +        gid = info->u.hvm.generation_id;
> >          break;
> >      case LIBXL_DOMAIN_TYPE_PV:
> >          hvm = 0;
> >          superpages = 0;
> >          pae = 1;
> > +        gid = 0;
> >          break;
> >      default:
> >          return ERROR_INVAL;
> > @@ -374,7 +379,7 @@ int libxl__domain_restore_common(libxl__
> >      rc = xc_domain_restore(ctx->xch, fd, domid,
> >                             state->store_port,
&state->store_mfn,
> >                             state->console_port, &state-
> >console_mfn,
> > -                           hvm, pae, superpages);
> > +                           hvm, pae, superpages, gid,
> > + &state->vm_gid_addr);
> >      if ( rc ) {
> >          LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "restoring
> domain");
> >          return ERROR_FAIL;
> > @@ -540,12 +545,22 @@ int libxl__domain_suspend_common(libxl__
> >      struct save_callbacks callbacks;
> >      struct suspendinfo si;
> >      int hvm, rc = ERROR_FAIL;
> > +    unsigned long vm_gid_addr;
> >
> >      switch (type) {
> > -    case LIBXL_DOMAIN_TYPE_HVM:
> > +    case LIBXL_DOMAIN_TYPE_HVM: {
> > +        char *path;
> > +        char *addr;
> > +
> > +        path = libxl__sprintf(gc, "%s/data/generation-id",
> libxl__xs_get_dompath(gc, domid));
> > +        addr = libxl__xs_read(gc, XBT_NULL, path);
> > +
> > +        vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
> >          hvm = 1;
> >          break;
> > +    }
> >      case LIBXL_DOMAIN_TYPE_PV:
> > +        vm_gid_addr = 0;
> >          hvm = 0;
> >          break;
> >      default:
> > @@ -583,7 +598,8 @@ int libxl__domain_suspend_common(libxl__
> >      callbacks.switch_qemu_logdirty >
libxl__domain_suspend_common_switch_qemu_logdirty;
> >      callbacks.data = &si;
> >
> > -    rc = xc_domain_save(ctx->xch, fd, domid, 0, 0, flags,
> &callbacks, hvm);
> > +    rc = xc_domain_save(ctx->xch, fd, domid, 0, 0, flags,
> &callbacks,
> > +                        hvm, vm_gid_addr);
> >      if ( rc ) {
> >          LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "saving domain:
> %s",
> >                           si.guest_responded ?
> > diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_internal.h
> > --- a/tools/libxl/libxl_internal.h  Wed Nov 30 07:18:11 2011 -
> 0800
> > +++ b/tools/libxl/libxl_internal.h  Wed Nov 30 20:51:07 2011
> +0000
> > @@ -199,6 +199,8 @@ typedef struct {
> >
> >      uint32_t console_port;
> >      unsigned long console_mfn;
> > +
> > +    unsigned long vm_gid_addr;
> >  } libxl__domain_build_state;
> >
> >  _hidden int libxl__build_pre(libxl__gc *gc, uint32_t domid, diff
> -r
> > 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_types.idl
> > --- a/tools/libxl/libxl_types.idl   Wed Nov 30 07:18:11 2011 -
> 0800
> > +++ b/tools/libxl/libxl_types.idl   Wed Nov 30 20:51:07 2011
> +0000
> > @@ -183,6 +183,7 @@ libxl_domain_build_info = Struct("domain
> >                                         ("vpt_align", bool),
> >                                         ("timer_mode",
integer),
> >                                         ("nested_hvm",
bool),
> > +                                       ("generation_id",
uint64),
> >                                         ])),
> >                   ("pv", Struct(None, [("kernel",
> libxl_file_reference),
> >                                        ("slack_memkb",
uint32),
> diff
> > -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxlu_cfg.c
> > --- a/tools/libxl/libxlu_cfg.c      Wed Nov 30 07:18:11 2011 -0800
> > +++ b/tools/libxl/libxlu_cfg.c      Wed Nov 30 20:51:07 2011 +0000
> > @@ -235,6 +235,37 @@ int xlu_cfg_get_long(const XLU_Config *c
> >      return 0;
> >  }
> >
> > +int xlu_cfg_get_long_long(const XLU_Config *cfg, const char *n,
> > +                          long long *value_r, int dont_warn) {
> > +    long long ll;
> > +    XLU_ConfigSetting *set;
> > +    int e;
> > +    char *ep;
> > +
> > +    e= find_atom(cfg,n,&set,dont_warn);  if (e) return e;
> > +    errno= 0; ll= strtoll(set->values[0], &ep, 0);
> > +    e= errno;
> > +    if (errno) {
> > +        e= errno;
> > +        assert(e==EINVAL || e==ERANGE);
> > +        if (!dont_warn)
> > +            fprintf(cfg->report,
> > +                    "%s:%d: warning: parameter `%s''
could not be
> parsed"
> > +                    " as a number: %s\n",
> > +                    cfg->filename, set->lineno, n,
strerror(e));
> > +        return e;
> > +    }
> > +    if (*ep || ep==set->values[0]) {
> > +        if (!dont_warn)
> > +            fprintf(cfg->report,
> > +                    "%s:%d: warning: parameter `%s'' is
not a
> valid number\n",
> > +                    cfg->filename, set->lineno, n);
> > +        return EINVAL;
> > +    }
> > +    *value_r= ll;
> > +    return 0;
> > +}
> > +
> >
> >  int xlu_cfg_get_list(const XLU_Config *cfg, const char *n,
> >                       XLU_ConfigList **list_r, int *entries_r, int
> > dont_warn) { diff -r 3c4c29899d8a -r 94a17182f386
> tools/libxl/libxlutil.h
> > --- a/tools/libxl/libxlutil.h       Wed Nov 30 07:18:11 2011 -0800
> > +++ b/tools/libxl/libxlutil.h       Wed Nov 30 20:51:07 2011 +0000
> > @@ -52,6 +52,8 @@ int xlu_cfg_replace_string(const XLU_Con
> >                             char **value_r, int dont_warn);  int
> > xlu_cfg_get_long(const XLU_Config*, const char *n, long *value_r,
> >                       int dont_warn);
> > +int xlu_cfg_get_long_long(const XLU_Config*, const char *n, long
> long *value_r,
> > +                          int dont_warn);
> >
> >  int xlu_cfg_get_list(const XLU_Config*, const char *n,
> >                       XLU_ConfigList **list_r /* may be 0 */, diff
> -r
> > 3c4c29899d8a -r 94a17182f386 tools/libxl/xl_cmdimpl.c
> > --- a/tools/libxl/xl_cmdimpl.c      Wed Nov 30 07:18:11 2011 -0800
> > +++ b/tools/libxl/xl_cmdimpl.c      Wed Nov 30 20:51:07 2011 +0000
> > @@ -573,6 +573,7 @@ static void parse_config_data(const char  {
> >      const char *buf;
> >      long l;
> > +    long long ll;
> >      XLU_Config *config;
> >      XLU_ConfigList *vbds, *nics, *pcis, *cvfbs, *cpuids;
> >      int pci_power_mgmt = 0;
> > @@ -764,6 +765,8 @@ static void parse_config_data(const char
> >              b_info->u.hvm.timer_mode = l;
> >          if (!xlu_cfg_get_long (config, "nestedhvm", &l,
0))
> >              b_info->u.hvm.nested_hvm = l;
> > +        if (!xlu_cfg_get_long_long (config,
"generation_id", &ll,
> 0))
> > +            b_info->u.hvm.nested_hvm = ll;
> >          break;
> >      case LIBXL_DOMAIN_TYPE_PV:
> >      {
> > diff -r 3c4c29899d8a -r 94a17182f386
> tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
> > --- a/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c  Wed
> Nov 30 07:18:11 2011 -0800
> > +++ b/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c  Wed
> Nov 30 20:51:07 2011 +0000
> > @@ -174,6 +174,7 @@ int checkpoint_start(checkpoint_state* s  {
> >      int hvm, rc;
> >      int flags = XCFLAGS_LIVE;
> > +    unsigned long vm_gid_addr;
> >
> >      if (!s->domid) {
> >         s->errstr = "checkpoint state not opened"; @@
-184,14
> +185,25
> > @@ int checkpoint_start(checkpoint_state* s
> >
> >      hvm = s->domtype > dt_pv;
> >      if (hvm) {
> > +       char path[128];
> > +       char *addr;
> > +
> > +       sprintf(path, "/local/domain/%u/data/generation-id",
s-
> >domid);
> > +       addr = xs_read(s->xsh, XBT_NULL, path, NULL);
> > +
> > +       vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
> > +       free(addr);
> > +
> >         flags |= XCFLAGS_HVM;
> >         if (switch_qemu_logdirty(s, 1))
> >             return -1;
> > +    } else {
> > +       vm_gid_addr = 0;
> >      }
> >
> >      callbacks->switch_qemu_logdirty = noop_switch_logdirty;
> >
> > -    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags,
> callbacks, hvm);
> > +    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags,
> callbacks,
> > + hvm, vm_gid_addr);
> >
> >      if (hvm)
> >         switch_qemu_logdirty(s, 0);
> > diff -r 3c4c29899d8a -r 94a17182f386 tools/xcutils/xc_restore.c
> > --- a/tools/xcutils/xc_restore.c    Wed Nov 30 07:18:11 2011 -0800
> > +++ b/tools/xcutils/xc_restore.c    Wed Nov 30 20:51:07 2011 +0000
> > @@ -23,7 +23,8 @@ main(int argc, char **argv)
> >      xc_interface *xch;
> >      int io_fd, ret;
> >      int superpages;
> > -    unsigned long store_mfn, console_mfn;
> > +    unsigned long store_mfn, console_mfn, vm_gid_addr;
> > +    uint64_t gid;
> >
> >      if ( (argc != 8) && (argc != 9) )
> >          errx(1, "usage: %s iofd domid store_evtchn "
> > @@ -40,19 +41,25 @@ main(int argc, char **argv)
> >      hvm  = atoi(argv[5]);
> >      pae  = atoi(argv[6]);
> >      apic = atoi(argv[7]);
> > -    if ( argc == 9 )
> > +    if ( argc >= 9 )
> >         superpages = atoi(argv[8]);
> >      else
> >         superpages = !!hvm;
> > +    if ( argc >= 10 )
> > +       gid = strtoll(argv[9], NULL, 0);
> > +    else
> > +       gid = 0;
> >
> >      ret = xc_domain_restore(xch, io_fd, domid, store_evtchn,
> &store_mfn,
> > -                            console_evtchn, &console_mfn, hvm,
> pae, superpages);
> > +                            console_evtchn, &console_mfn, hvm,
> pae, superpages,
> > +                            gid, &vm_gid_addr);
> >
> >      if ( ret == 0 )
> >      {
> >     printf("store-mfn %li\n", store_mfn);
> >          if ( !hvm )
> >              printf("console-mfn %li\n", console_mfn);
> > +   printf("vm-gid-addr %lx\n", vm_gid_addr);
> >     fflush(stdout);
> >      }
> >
> > diff -r 3c4c29899d8a -r 94a17182f386 tools/xcutils/xc_save.c
> > --- a/tools/xcutils/xc_save.c       Wed Nov 30 07:18:11 2011 -0800
> > +++ b/tools/xcutils/xc_save.c       Wed Nov 30 20:51:07 2011 +0000
> > @@ -169,6 +169,10 @@ main(int argc, char **argv)
> >      unsigned int maxit, max_f;
> >      int io_fd, ret, port;
> >      struct save_callbacks callbacks;
> > +    char path[128];
> > +    struct xs_handle *xs;
> > +    char *addr;
> > +    unsigned long vm_gid_addr;
> >
> >      if (argc != 6)
> >          errx(1, "usage: %s iofd domid maxit maxf flags",
> argv[0]); @@
> > -207,8 +211,21 @@ main(int argc, char **argv)
> >      memset(&callbacks, 0, sizeof(callbacks));
> >      callbacks.suspend = suspend;
> >      callbacks.switch_qemu_logdirty = switch_qemu_logdirty;
> > +
> > +    sprintf(path, "/local/domain/%d/data/generation-id",
> si.domid);
> > +
> > +    if ((xs = xs_daemon_open()) == NULL)
> > +        errx(1, "Couldn''t contact xenstore");
> > +
> > +    addr = xs_read(xs, XBT_NULL, path, NULL);
> > +
> > +    xs_daemon_close(xs);
> > +
> > +    vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
> > +    free(addr);
> > +
> >      ret = xc_domain_save(si.xch, io_fd, si.domid, maxit, max_f,
> si.flags,
> > -                         &callbacks, !!(si.flags &
XCFLAGS_HVM));
> > +                         &callbacks, !!(si.flags &
XCFLAGS_HVM),
> > + vm_gid_addr);
> >
> >      if (si.suspend_evtchn > 0)
> >      xc_suspend_evtchn_release(si.xch, si.xce, si.domid,
> > si.suspend_evtchn);
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel

On Thu, 2011-12-01 at 08:46 +0000, Paul Durrant wrote:
> Konrad,
> 
>   Did you see my previous patch set? The introductory comment was:

I think that description belongs somewhere permanent, either in
docs/misc or as a comment in an appropriate header.

Ian.
> 
> -----
> The following is a revised patch series to add support for a VM generation
ID virtual device for HVM guests.
> The basic requirements of this device are as follows:
> 
> - It must be exposed somewhere in ACPI namespace with a _CID of
>   "VM_Gen_Counter".
> - It must also include a _DDN of "VM_Gen_Counter".
> - It must contain a _HID object but no particular value is
>   required.
> - It must expose a package called ADDR which evaluates to two
>   integers; the first being the low order 32-bits of a guest
>   physical address (GPA), the second by the high order 32-bits of
>   the GPA. This GPA is the address of an 8-byte aligned 8-byte
>   buffer containing the VM generation ID.
>   This buffer must not be in ranges supported as AddressRangeMemory
>   or AddressRangeACPI and must not be mapped by any PTE with caching
>   disabled.
> 
> The semantics of the VM generation ID itself are left up to the tools but
it must be possible to change it each time the VM is booted, migrated, or
restored from a saved image.
> -----
> 
>   Does that help?
> 
>     Paul
> 
> > -----Original Message-----
> > From: Konrad Rzeszutek Wilk [mailto:konrad@darnok.org]
> > Sent: 30 November 2011 22:14
> > To: Paul Durrant
> > Cc: xen-devel@lists.xensource.com
> > Subject: Re: [Xen-devel] [PATCH] Add code to track the address of
> > the VM generation id buffer across a
> >
> > On Wed, Nov 30, 2011 at 08:58:37PM +0000, Paul Durrant wrote:
> > > # HG changeset patch
> > > # User Paul Durrant <paul.durrant@citrix.com> # Date
1322686267 0
> > #
> > > Node ID 94a17182f386c8bb414eba55dddf763b8982c76d
> > > # Parent  3c4c29899d8a2a0c0f9109b7236da95bb72b77b6
> > > Add code to track the address of the VM generation id buffer
> > across a
> > > save/restore or migrate and inject a new value.
> >
> > So what is a generation id? What is the use-case for this?
> >
> > > The address of the buffer is written into xenstore by hvmloader
at
> > > boot time. It must be read from xenstore by the caller of
> > > xc_domain_save() and then written back again by the caller of
> > > xc_domain_restore().
> > >
> > > Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
> > >
> > > diff -r 3c4c29899d8a -r 94a17182f386
> > tools/libxc/ia64/xc_ia64_linux_restore.c
> > > --- a/tools/libxc/ia64/xc_ia64_linux_restore.c      Wed Nov 30
> > 07:18:11 2011 -0800
> > > +++ b/tools/libxc/ia64/xc_ia64_linux_restore.c      Wed Nov 30
> > 20:51:07 2011 +0000
> > > @@ -548,7 +548,8 @@ int
> > >  xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
> > >                    unsigned int store_evtchn, unsigned long
> > *store_mfn,
> > >                    unsigned int console_evtchn, unsigned long
> > *console_mfn,
> > > -                  unsigned int hvm, unsigned int pae, int
> > superpages)
> > > +                  unsigned int hvm, unsigned int pae, int
> > superpages,
> > > +                  uint64_t gid)
> > >  {
> > >      DECLARE_DOMCTL;
> > >      int rc = 1;
> > > diff -r 3c4c29899d8a -r 94a17182f386
> > tools/libxc/ia64/xc_ia64_linux_save.c
> > > --- a/tools/libxc/ia64/xc_ia64_linux_save.c Wed Nov 30 07:18:11
> > 2011 -0800
> > > +++ b/tools/libxc/ia64/xc_ia64_linux_save.c Wed Nov 30 20:51:07
> > 2011 +0000
> > > @@ -382,7 +382,8 @@ out:
> > >  int
> > >  xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom,
> > uint32_t max_iters,
> > >                 uint32_t max_factor, uint32_t flags,
> > > -               struct save_callbacks* callbacks, int hvm)
> > > +               struct save_callbacks* callbacks, int hvm,
> > > +               unsigned long vm_gid_addr)
> > >  {
> > >      DECLARE_DOMCTL;
> > >      xc_dominfo_t info;
> > > diff -r 3c4c29899d8a -r 94a17182f386
> > tools/libxc/xc_domain_restore.c
> > > --- a/tools/libxc/xc_domain_restore.c       Wed Nov 30 07:18:11
2011 -
> > 0800
> > > +++ b/tools/libxc/xc_domain_restore.c       Wed Nov 30 20:51:07
2011
> > +0000
> > > @@ -676,6 +676,7 @@ typedef struct {
> > >      uint64_t console_pfn;
> > >      uint64_t acpi_ioport_location;
> > >      uint64_t viridian;
> > > +    uint64_t vm_gid_addr;
> > >  } pagebuf_t;
> > >
> > >  static int pagebuf_init(pagebuf_t* buf) @@ -820,6 +821,17 @@
> > static
> > > int pagebuf_get_one(xc_interface
> > >          }
> > >          return pagebuf_get_one(xch, ctx, buf, fd, dom);
> > >
> > > +    case XC_SAVE_ID_HVM_GENERATION_ID_ADDR:
> > > +        /* Skip padding 4 bytes then read the generation id
> > buffer location. */
> > > +        if ( RDEXACT(fd, &buf->vm_gid_addr,
sizeof(uint32_t)) ||
> > > +             RDEXACT(fd, &buf->vm_gid_addr,
sizeof(uint64_t)) )
> > > +        {
> > > +            PERROR("error read the generation id buffer
> > location");
> > > +            return -1;
> > > +        }
> > > +        DPRINTF("read generation id buffer address");
> > > +        return pagebuf_get_one(xch, ctx, buf, fd, dom);
> > > +
> > >      default:
> > >          if ( (count > MAX_BATCH_SIZE) || (count < 0) ) {
> > >              ERROR("Max batch size exceeded (%d). Giving
up.",
> > count);
> > > @@ -1186,7 +1198,8 @@ static int apply_batch(xc_interface *xch
> > int
> > > xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
> > >                        unsigned int store_evtchn, unsigned long
> > *store_mfn,
> > >                        unsigned int console_evtchn, unsigned long
> > *console_mfn,
> > > -                      unsigned int hvm, unsigned int pae, int
> > superpages)
> > > +                      unsigned int hvm, unsigned int pae, int
> > superpages,
> > > +                      uint64_t gid, unsigned long *vm_gid_addr)
> > >  {
> > >      DECLARE_DOMCTL;
> > >      int rc = 1, frc, i, j, n, m, pae_extended_cr3 = 0,
> > > ext_vcpucontext = 0; @@ -1386,6 +1399,33 @@ int
> > xc_domain_restore(xc_interface *xch,
> > >                  xc_set_hvm_param(xch, dom, HVM_PARAM_VM86_TSS,
> > pagebuf.vm86_tss);
> > >              if ( pagebuf.console_pfn )
> > >                  console_pfn = pagebuf.console_pfn;
> > > +            if ( pagebuf.vm_gid_addr ) {
> > > +                unsigned int offset;
> > > +                unsigned char *buf;
> > > +
> > > +                /*
> > > +                 * Map the VM generation id buffer and inject
the
> > new value.
> > > +                 */
> > > +
> > > +                pfn = pagebuf.vm_gid_addr >> PAGE_SHIFT;
> > > +                offset = pagebuf.vm_gid_addr & (PAGE_SIZE -
1);
> > > +
> > > +                if ( (pfn >= dinfo->p2m_size) ||
> > > +                     (pfn_type[pfn] != XEN_DOMCTL_PFINFO_NOTAB)
)
> > > +                {
> > > +                    ERROR("generation id buffer frame is
bad");
> > > +                    goto out;
> > > +                }
> > > +
> > > +                mfn = ctx->p2m[pfn];
> > > +                buf = xc_map_foreign_range(xch, dom, PAGE_SIZE,
> > > +                                           PROT_READ |
> > PROT_WRITE, mfn);
> > > +                *(unsigned long long *)(buf + offset) = gid;
> > > +                munmap(buf, PAGE_SIZE);
> > > +
> > > +                *vm_gid_addr = pagebuf.vm_gid_addr;
> > > +            }
> > > +
> > >              break;  /* our work here is done */
> > >          }
> > >
> > > diff -r 3c4c29899d8a -r 94a17182f386 tools/libxc/xc_domain_save.c
> > > --- a/tools/libxc/xc_domain_save.c  Wed Nov 30 07:18:11 2011 -
> > 0800
> > > +++ b/tools/libxc/xc_domain_save.c  Wed Nov 30 20:51:07 2011
> > +0000
> > > @@ -754,7 +754,8 @@ static int save_tsc_info(xc_interface *x
> > >
> > >  int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom,
> > uint32_t max_iters,
> > >                     uint32_t max_factor, uint32_t flags,
> > > -                   struct save_callbacks* callbacks, int hvm)
> > > +                   struct save_callbacks* callbacks, int hvm,
> > > +                   unsigned long vm_gid_addr)
> > >  {
> > >      xc_dominfo_t info;
> > >      DECLARE_DOMCTL;
> > > @@ -1460,6 +1461,16 @@ int xc_domain_save(xc_interface *xch, in
> > >              uint64_t data;
> > >          } chunk = { 0, };
> > >
> > > +        chunk.id = XC_SAVE_ID_HVM_GENERATION_ID_ADDR;
> > > +        chunk.data = vm_gid_addr;
> > > +
> > > +        if ( (chunk.data != 0) &&
> > > +             wrexact(io_fd, &chunk, sizeof(chunk)) )
> > > +        {
> > > +            PERROR("Error when writing the generation id
buffer
> > location for guest");
> > > +            goto out;
> > > +        }
> > > +
> > >          chunk.id = XC_SAVE_ID_HVM_IDENT_PT;
> > >          chunk.data = 0;
> > >          xc_get_hvm_param(xch, dom, HVM_PARAM_IDENT_PT, diff -r
> > > 3c4c29899d8a -r 94a17182f386 tools/libxc/xenguest.h
> > > --- a/tools/libxc/xenguest.h        Wed Nov 30 07:18:11 2011
-0800
> > > +++ b/tools/libxc/xenguest.h        Wed Nov 30 20:51:07 2011
+0000
> > > @@ -57,7 +57,8 @@ struct save_callbacks {
> > >   */
> > >  int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom,
> > uint32_t max_iters,
> > >                     uint32_t max_factor, uint32_t flags /*
> > XCFLAGS_xxx */,
> > > -                   struct save_callbacks* callbacks, int hvm);
> > > +                   struct save_callbacks* callbacks, int hvm,
> > > +                   unsigned long vm_gid_addr);
> > >
> > >
> > >  /**
> > > @@ -71,12 +72,15 @@ int xc_domain_save(xc_interface *xch, in
> > >   * @parm hvm non-zero if this is a HVM restore
> > >   * @parm pae non-zero if this HVM domain has PAE support enabled
> > >   * @parm superpages non-zero to allocate guest memory with
> > superpages
> > > + * @parm gid the new generation id of the VM
> > > + * @parm vm_gid_addr returned with the address of the generation
> > id
> > > + buffer
> > >   * @return 0 on success, -1 on failure
> > >   */
> > >  int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t
dom,
> > >                        unsigned int store_evtchn, unsigned long
> > *store_mfn,
> > >                        unsigned int console_evtchn, unsigned long
> > *console_mfn,
> > > -                      unsigned int hvm, unsigned int pae, int
> > superpages);
> > > +                      unsigned int hvm, unsigned int pae, int
> > superpages,
> > > +                      uint64_t gid, unsigned long *vm_gid_addr);
> > >  /**
> > >   * xc_domain_restore writes a file to disk that contains the
> > device
> > >   * model saved state.
> > > diff -r 3c4c29899d8a -r 94a17182f386
tools/libxc/xg_save_restore.h
> > > --- a/tools/libxc/xg_save_restore.h Wed Nov 30 07:18:11 2011 -
> > 0800
> > > +++ b/tools/libxc/xg_save_restore.h Wed Nov 30 20:51:07 2011
> > +0000
> > > @@ -135,6 +135,7 @@
> > >  #define XC_SAVE_ID_LAST_CHECKPOINT    -9 /* Commit to restoring
> > after completion of current iteration. */
> > >  #define XC_SAVE_ID_HVM_ACPI_IOPORTS_LOCATION -10
> > >  #define XC_SAVE_ID_HVM_VIRIDIAN       -11
> > > +#define XC_SAVE_ID_HVM_GENERATION_ID_ADDR -12
> > >
> > >  /*
> > >  ** We process save/restore/migrate in batches of pages; the
below
> > > diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_create.c
> > > --- a/tools/libxl/libxl_create.c    Wed Nov 30 07:18:11 2011
-0800
> > > +++ b/tools/libxl/libxl_create.c    Wed Nov 30 20:51:07 2011
+0000
> > > @@ -101,6 +101,7 @@ int libxl_init_build_info(libxl_ctx *ctx
> > >          b_info->u.hvm.vpt_align = 1;
> > >          b_info->u.hvm.timer_mode = 1;
> > >          b_info->u.hvm.nested_hvm = 0;
> > > +        b_info->u.hvm.generation_id = 0;
> > >          break;
> > >      case LIBXL_DOMAIN_TYPE_PV:
> > >          b_info->u.pv.slack_memkb = 8 * 1024; @@ -191,13
+192,15
> > @@
> > > int libxl__domain_build(libxl__gc *gc,
> > >          vments[4] = "start_time";
> > >          vments[5] = libxl__sprintf(gc, "%lu.%02d",
> > > start_time.tv_sec,(int)start_time.tv_usec/10000);
> > >
> > > -        localents = libxl__calloc(gc, 7, sizeof(char *));
> > > +        localents = libxl__calloc(gc, 9, sizeof(char *));
> > >          localents[0] = "platform/acpi";
> > >          localents[1] = (info->u.hvm.acpi) ? "1" :
"0";
> > >          localents[2] = "platform/acpi_s3";
> > >          localents[3] = (info->u.hvm.acpi_s3) ? "1"
: "0";
> > >          localents[4] = "platform/acpi_s4";
> > >          localents[5] = (info->u.hvm.acpi_s4) ? "1"
: "0";
> > > +        localents[6] = "platform/generation_id";
> > > +        localents[7] = libxl__sprintf(gc, "0x%llx",
> > > + info->u.hvm.generation_id);
> > >
> > >          break;
> > >      case LIBXL_DOMAIN_TYPE_PV:
> > > diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_dom.c
> > > --- a/tools/libxl/libxl_dom.c       Wed Nov 30 07:18:11 2011
-0800
> > > +++ b/tools/libxl/libxl_dom.c       Wed Nov 30 20:51:07 2011
+0000
> > > @@ -125,7 +125,7 @@ int libxl__build_post(libxl__gc *gc, uin
> > >      if (info->cpuid != NULL)
> > >          libxl_cpuid_set(ctx, domid, info->cpuid);
> > >
> > > -    ents = libxl__calloc(gc, 12 + (info->max_vcpus * 2) + 2,
> > sizeof(char *));
> > > +    ents = libxl__calloc(gc, 14 + (info->max_vcpus * 2) + 2,
> > > + sizeof(char *));
> > >      ents[0] = "memory/static-max";
> > >      ents[1] = libxl__sprintf(gc, "%d",
info->max_memkb);
> > >      ents[2] = "memory/target";
> > > @@ -138,9 +138,11 @@ int libxl__build_post(libxl__gc *gc, uin
> > >      ents[9] = libxl__sprintf(gc, "%"PRIu32,
state->store_port);
> > >      ents[10] = "store/ring-ref";
> > >      ents[11] = libxl__sprintf(gc, "%lu",
state->store_mfn);
> > > +    ents[12] = "data/generation-id";
> > > +    ents[13] = libxl__sprintf(gc, "0x%lx",
state->vm_gid_addr);
> > >      for (i = 0; i < info->max_vcpus; i++) {
> > > -        ents[12+(i*2)]   = libxl__sprintf(gc,
> > "cpu/%d/availability", i);
> > > -        ents[12+(i*2)+1] = (i && info->cur_vcpus
&& !(info-
> > >cur_vcpus & (1 << i)))
> > > +        ents[14+(i*2)]   = libxl__sprintf(gc,
> > "cpu/%d/availability", i);
> > > +        ents[14+(i*2)+1] = (i && info->cur_vcpus
&& !(info-
> > >cur_vcpus
> > > + & (1 << i)))
> > >                              ? "offline" :
"online";
> > >      }
> > >
> > > @@ -357,16 +359,19 @@ int libxl__domain_restore_common(libxl__
> > >      /* read signature */
> > >      int rc;
> > >      int hvm, pae, superpages;
> > > +    uint64_t gid;
> > >      switch (info->type) {
> > >      case LIBXL_DOMAIN_TYPE_HVM:
> > >          hvm = 1;
> > >          superpages = 1;
> > >          pae = info->u.hvm.pae;
> > > +        gid = info->u.hvm.generation_id;
> > >          break;
> > >      case LIBXL_DOMAIN_TYPE_PV:
> > >          hvm = 0;
> > >          superpages = 0;
> > >          pae = 1;
> > > +        gid = 0;
> > >          break;
> > >      default:
> > >          return ERROR_INVAL;
> > > @@ -374,7 +379,7 @@ int libxl__domain_restore_common(libxl__
> > >      rc = xc_domain_restore(ctx->xch, fd, domid,
> > >                             state->store_port,
&state->store_mfn,
> > >                             state->console_port, &state-
> > >console_mfn,
> > > -                           hvm, pae, superpages);
> > > +                           hvm, pae, superpages, gid,
> > > + &state->vm_gid_addr);
> > >      if ( rc ) {
> > >          LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "restoring
> > domain");
> > >          return ERROR_FAIL;
> > > @@ -540,12 +545,22 @@ int libxl__domain_suspend_common(libxl__
> > >      struct save_callbacks callbacks;
> > >      struct suspendinfo si;
> > >      int hvm, rc = ERROR_FAIL;
> > > +    unsigned long vm_gid_addr;
> > >
> > >      switch (type) {
> > > -    case LIBXL_DOMAIN_TYPE_HVM:
> > > +    case LIBXL_DOMAIN_TYPE_HVM: {
> > > +        char *path;
> > > +        char *addr;
> > > +
> > > +        path = libxl__sprintf(gc,
"%s/data/generation-id",
> > libxl__xs_get_dompath(gc, domid));
> > > +        addr = libxl__xs_read(gc, XBT_NULL, path);
> > > +
> > > +        vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
> > >          hvm = 1;
> > >          break;
> > > +    }
> > >      case LIBXL_DOMAIN_TYPE_PV:
> > > +        vm_gid_addr = 0;
> > >          hvm = 0;
> > >          break;
> > >      default:
> > > @@ -583,7 +598,8 @@ int libxl__domain_suspend_common(libxl__
> > >      callbacks.switch_qemu_logdirty > >
libxl__domain_suspend_common_switch_qemu_logdirty;
> > >      callbacks.data = &si;
> > >
> > > -    rc = xc_domain_save(ctx->xch, fd, domid, 0, 0, flags,
> > &callbacks, hvm);
> > > +    rc = xc_domain_save(ctx->xch, fd, domid, 0, 0, flags,
> > &callbacks,
> > > +                        hvm, vm_gid_addr);
> > >      if ( rc ) {
> > >          LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "saving
domain:
> > %s",
> > >                           si.guest_responded ?
> > > diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_internal.h
> > > --- a/tools/libxl/libxl_internal.h  Wed Nov 30 07:18:11 2011 -
> > 0800
> > > +++ b/tools/libxl/libxl_internal.h  Wed Nov 30 20:51:07 2011
> > +0000
> > > @@ -199,6 +199,8 @@ typedef struct {
> > >
> > >      uint32_t console_port;
> > >      unsigned long console_mfn;
> > > +
> > > +    unsigned long vm_gid_addr;
> > >  } libxl__domain_build_state;
> > >
> > >  _hidden int libxl__build_pre(libxl__gc *gc, uint32_t domid, diff
> > -r
> > > 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_types.idl
> > > --- a/tools/libxl/libxl_types.idl   Wed Nov 30 07:18:11 2011 -
> > 0800
> > > +++ b/tools/libxl/libxl_types.idl   Wed Nov 30 20:51:07 2011
> > +0000
> > > @@ -183,6 +183,7 @@ libxl_domain_build_info = Struct("domain
> > >                                         ("vpt_align",
bool),
> > >                                         ("timer_mode",
integer),
> > >                                         ("nested_hvm",
bool),
> > > +                                      
("generation_id", uint64),
> > >                                         ])),
> > >                   ("pv", Struct(None,
[("kernel",
> > libxl_file_reference),
> > >                                        ("slack_memkb",
uint32),
> > diff
> > > -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxlu_cfg.c
> > > --- a/tools/libxl/libxlu_cfg.c      Wed Nov 30 07:18:11 2011
-0800
> > > +++ b/tools/libxl/libxlu_cfg.c      Wed Nov 30 20:51:07 2011
+0000
> > > @@ -235,6 +235,37 @@ int xlu_cfg_get_long(const XLU_Config *c
> > >      return 0;
> > >  }
> > >
> > > +int xlu_cfg_get_long_long(const XLU_Config *cfg, const char *n,
> > > +                          long long *value_r, int dont_warn) {
> > > +    long long ll;
> > > +    XLU_ConfigSetting *set;
> > > +    int e;
> > > +    char *ep;
> > > +
> > > +    e= find_atom(cfg,n,&set,dont_warn);  if (e) return e;
> > > +    errno= 0; ll= strtoll(set->values[0], &ep, 0);
> > > +    e= errno;
> > > +    if (errno) {
> > > +        e= errno;
> > > +        assert(e==EINVAL || e==ERANGE);
> > > +        if (!dont_warn)
> > > +            fprintf(cfg->report,
> > > +                    "%s:%d: warning: parameter
`%s'' could not be
> > parsed"
> > > +                    " as a number: %s\n",
> > > +                    cfg->filename, set->lineno, n,
strerror(e));
> > > +        return e;
> > > +    }
> > > +    if (*ep || ep==set->values[0]) {
> > > +        if (!dont_warn)
> > > +            fprintf(cfg->report,
> > > +                    "%s:%d: warning: parameter
`%s'' is not a
> > valid number\n",
> > > +                    cfg->filename, set->lineno, n);
> > > +        return EINVAL;
> > > +    }
> > > +    *value_r= ll;
> > > +    return 0;
> > > +}
> > > +
> > >
> > >  int xlu_cfg_get_list(const XLU_Config *cfg, const char *n,
> > >                       XLU_ConfigList **list_r, int *entries_r,
int
> > > dont_warn) { diff -r 3c4c29899d8a -r 94a17182f386
> > tools/libxl/libxlutil.h
> > > --- a/tools/libxl/libxlutil.h       Wed Nov 30 07:18:11 2011
-0800
> > > +++ b/tools/libxl/libxlutil.h       Wed Nov 30 20:51:07 2011
+0000
> > > @@ -52,6 +52,8 @@ int xlu_cfg_replace_string(const XLU_Con
> > >                             char **value_r, int dont_warn);  int
> > > xlu_cfg_get_long(const XLU_Config*, const char *n, long *value_r,
> > >                       int dont_warn);
> > > +int xlu_cfg_get_long_long(const XLU_Config*, const char *n, long
> > long *value_r,
> > > +                          int dont_warn);
> > >
> > >  int xlu_cfg_get_list(const XLU_Config*, const char *n,
> > >                       XLU_ConfigList **list_r /* may be 0 */,
diff
> > -r
> > > 3c4c29899d8a -r 94a17182f386 tools/libxl/xl_cmdimpl.c
> > > --- a/tools/libxl/xl_cmdimpl.c      Wed Nov 30 07:18:11 2011
-0800
> > > +++ b/tools/libxl/xl_cmdimpl.c      Wed Nov 30 20:51:07 2011
+0000
> > > @@ -573,6 +573,7 @@ static void parse_config_data(const char  {
> > >      const char *buf;
> > >      long l;
> > > +    long long ll;
> > >      XLU_Config *config;
> > >      XLU_ConfigList *vbds, *nics, *pcis, *cvfbs, *cpuids;
> > >      int pci_power_mgmt = 0;
> > > @@ -764,6 +765,8 @@ static void parse_config_data(const char
> > >              b_info->u.hvm.timer_mode = l;
> > >          if (!xlu_cfg_get_long (config, "nestedhvm",
&l, 0))
> > >              b_info->u.hvm.nested_hvm = l;
> > > +        if (!xlu_cfg_get_long_long (config,
"generation_id", &ll,
> > 0))
> > > +            b_info->u.hvm.nested_hvm = ll;
> > >          break;
> > >      case LIBXL_DOMAIN_TYPE_PV:
> > >      {
> > > diff -r 3c4c29899d8a -r 94a17182f386
> > tools/python/xen/lowlevel/checkpoint/libcheckpoint.c
> > > --- a/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c  Wed
> > Nov 30 07:18:11 2011 -0800
> > > +++ b/tools/python/xen/lowlevel/checkpoint/libcheckpoint.c  Wed
> > Nov 30 20:51:07 2011 +0000
> > > @@ -174,6 +174,7 @@ int checkpoint_start(checkpoint_state* s  {
> > >      int hvm, rc;
> > >      int flags = XCFLAGS_LIVE;
> > > +    unsigned long vm_gid_addr;
> > >
> > >      if (!s->domid) {
> > >         s->errstr = "checkpoint state not opened";
@@ -184,14
> > +185,25
> > > @@ int checkpoint_start(checkpoint_state* s
> > >
> > >      hvm = s->domtype > dt_pv;
> > >      if (hvm) {
> > > +       char path[128];
> > > +       char *addr;
> > > +
> > > +       sprintf(path,
"/local/domain/%u/data/generation-id", s-
> > >domid);
> > > +       addr = xs_read(s->xsh, XBT_NULL, path, NULL);
> > > +
> > > +       vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
> > > +       free(addr);
> > > +
> > >         flags |= XCFLAGS_HVM;
> > >         if (switch_qemu_logdirty(s, 1))
> > >             return -1;
> > > +    } else {
> > > +       vm_gid_addr = 0;
> > >      }
> > >
> > >      callbacks->switch_qemu_logdirty = noop_switch_logdirty;
> > >
> > > -    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags,
> > callbacks, hvm);
> > > +    rc = xc_domain_save(s->xch, fd, s->domid, 0, 0, flags,
> > callbacks,
> > > + hvm, vm_gid_addr);
> > >
> > >      if (hvm)
> > >         switch_qemu_logdirty(s, 0);
> > > diff -r 3c4c29899d8a -r 94a17182f386 tools/xcutils/xc_restore.c
> > > --- a/tools/xcutils/xc_restore.c    Wed Nov 30 07:18:11 2011
-0800
> > > +++ b/tools/xcutils/xc_restore.c    Wed Nov 30 20:51:07 2011
+0000
> > > @@ -23,7 +23,8 @@ main(int argc, char **argv)
> > >      xc_interface *xch;
> > >      int io_fd, ret;
> > >      int superpages;
> > > -    unsigned long store_mfn, console_mfn;
> > > +    unsigned long store_mfn, console_mfn, vm_gid_addr;
> > > +    uint64_t gid;
> > >
> > >      if ( (argc != 8) && (argc != 9) )
> > >          errx(1, "usage: %s iofd domid store_evtchn "
> > > @@ -40,19 +41,25 @@ main(int argc, char **argv)
> > >      hvm  = atoi(argv[5]);
> > >      pae  = atoi(argv[6]);
> > >      apic = atoi(argv[7]);
> > > -    if ( argc == 9 )
> > > +    if ( argc >= 9 )
> > >         superpages = atoi(argv[8]);
> > >      else
> > >         superpages = !!hvm;
> > > +    if ( argc >= 10 )
> > > +       gid = strtoll(argv[9], NULL, 0);
> > > +    else
> > > +       gid = 0;
> > >
> > >      ret = xc_domain_restore(xch, io_fd, domid, store_evtchn,
> > &store_mfn,
> > > -                            console_evtchn, &console_mfn,
hvm,
> > pae, superpages);
> > > +                            console_evtchn, &console_mfn,
hvm,
> > pae, superpages,
> > > +                            gid, &vm_gid_addr);
> > >
> > >      if ( ret == 0 )
> > >      {
> > >     printf("store-mfn %li\n", store_mfn);
> > >          if ( !hvm )
> > >              printf("console-mfn %li\n", console_mfn);
> > > +   printf("vm-gid-addr %lx\n", vm_gid_addr);
> > >     fflush(stdout);
> > >      }
> > >
> > > diff -r 3c4c29899d8a -r 94a17182f386 tools/xcutils/xc_save.c
> > > --- a/tools/xcutils/xc_save.c       Wed Nov 30 07:18:11 2011
-0800
> > > +++ b/tools/xcutils/xc_save.c       Wed Nov 30 20:51:07 2011
+0000
> > > @@ -169,6 +169,10 @@ main(int argc, char **argv)
> > >      unsigned int maxit, max_f;
> > >      int io_fd, ret, port;
> > >      struct save_callbacks callbacks;
> > > +    char path[128];
> > > +    struct xs_handle *xs;
> > > +    char *addr;
> > > +    unsigned long vm_gid_addr;
> > >
> > >      if (argc != 6)
> > >          errx(1, "usage: %s iofd domid maxit maxf
flags",
> > argv[0]); @@
> > > -207,8 +211,21 @@ main(int argc, char **argv)
> > >      memset(&callbacks, 0, sizeof(callbacks));
> > >      callbacks.suspend = suspend;
> > >      callbacks.switch_qemu_logdirty = switch_qemu_logdirty;
> > > +
> > > +    sprintf(path,
"/local/domain/%d/data/generation-id",
> > si.domid);
> > > +
> > > +    if ((xs = xs_daemon_open()) == NULL)
> > > +        errx(1, "Couldn''t contact xenstore");
> > > +
> > > +    addr = xs_read(xs, XBT_NULL, path, NULL);
> > > +
> > > +    xs_daemon_close(xs);
> > > +
> > > +    vm_gid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
> > > +    free(addr);
> > > +
> > >      ret = xc_domain_save(si.xch, io_fd, si.domid, maxit, max_f,
> > si.flags,
> > > -                         &callbacks, !!(si.flags &
XCFLAGS_HVM));
> > > +                         &callbacks, !!(si.flags &
XCFLAGS_HVM),
> > > + vm_gid_addr);
> > >
> > >      if (si.suspend_evtchn > 0)
> > >      xc_suspend_evtchn_release(si.xch, si.xce, si.domid,
> > > si.suspend_evtchn);
> > >
> > > _______________________________________________
> > > Xen-devel mailing list
> > > Xen-devel@lists.xensource.com
> > > http://lists.xensource.com/xen-devel
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

On Wed, 2011-11-30 at 20:58 +0000, Paul Durrant wrote:
> diff -r 3c4c29899d8a -r 94a17182f386
> tools/libxc/ia64/xc_ia64_linux_restore.c
> --- a/tools/libxc/ia64/xc_ia64_linux_restore.c  Wed Nov 30 07:18:11
> 2011 -0800
> +++ b/tools/libxc/ia64/xc_ia64_linux_restore.c  Wed Nov 30 20:51:07
> 2011 +0000
> @@ -548,7 +548,8 @@ int
>  xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
>                    unsigned int store_evtchn, unsigned long
> *store_mfn,
>                    unsigned int console_evtchn, unsigned long
> *console_mfn,
> -                  unsigned int hvm, unsigned int pae, int superpages)
> +                  unsigned int hvm, unsigned int pae, int superpages,
> +                  uint64_t gid)
This is a uint64_t * in the non-ia64 case. is that right?
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_internal.h
> --- a/tools/libxl/libxl_internal.h      Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/libxl_internal.h      Wed Nov 30 20:51:07 2011 +0000
> @@ -199,6 +199,8 @@ typedef struct {
> 
>      uint32_t console_port;
>      unsigned long console_mfn;
> +
> +    unsigned long vm_gid_addr;
Is this large enough for a 64 bit guest even with 32 bit tools?
>  } libxl__domain_build_state;
> 
>  _hidden int libxl__build_pre(libxl__gc *gc, uint32_t domid,
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/libxl_types.idl
> --- a/tools/libxl/libxl_types.idl       Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/libxl_types.idl       Wed Nov 30 20:51:07 2011 +0000
> @@ -183,6 +183,7 @@ libxl_domain_build_info = Struct("domain
>                                         ("vpt_align", bool),
>                                         ("timer_mode", integer),
>                                         ("nested_hvm", bool),
> +                                       ("generation_id",
uint64),
>                                         ])),
>                   ("pv", Struct(None, [("kernel",
libxl_file_reference),
>                                        ("slack_memkb", uint32),
> diff -r 3c4c29899d8a -r 94a17182f386 tools/libxl/xl_cmdimpl.c
> --- a/tools/libxl/xl_cmdimpl.c  Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/libxl/xl_cmdimpl.c  Wed Nov 30 20:51:07 2011 +0000
> @@ -573,6 +573,7 @@ static void parse_config_data(const char
>  {
>      const char *buf;
>      long l;
> +    long long ll;
>      XLU_Config *config;
>      XLU_ConfigList *vbds, *nics, *pcis, *cvfbs, *cpuids;
>      int pci_power_mgmt = 0;
> @@ -764,6 +765,8 @@ static void parse_config_data(const char
>              b_info->u.hvm.timer_mode = l;
>          if (!xlu_cfg_get_long (config, "nestedhvm", &l, 0))
>              b_info->u.hvm.nested_hvm = l;
> +        if (!xlu_cfg_get_long_long (config, "generation_id",
&ll, 0))
> +            b_info->u.hvm.nested_hvm = ll;
Are you you tested this?

Also please patch docs/man/xl.cfg.pod.5 with a description of this new
key.
> diff -r 3c4c29899d8a -r 94a17182f386 tools/xcutils/xc_restore.c
> --- a/tools/xcutils/xc_restore.c        Wed Nov 30 07:18:11 2011 -0800
> +++ b/tools/xcutils/xc_restore.c        Wed Nov 30 20:51:07 2011 +0000
> @@ -23,7 +23,8 @@ main(int argc, char **argv)
>      xc_interface *xch;
>      int io_fd, ret;
>      int superpages;
> -    unsigned long store_mfn, console_mfn;
> +    unsigned long store_mfn, console_mfn, vm_gid_addr;
> +    uint64_t gid;
> 
>      if ( (argc != 8) && (argc != 9) )
>          errx(1, "usage: %s iofd domid store_evtchn "
> @@ -40,19 +41,25 @@ main(int argc, char **argv)
>      hvm  = atoi(argv[5]);
>      pae  = atoi(argv[6]);
>      apic = atoi(argv[7]);
> -    if ( argc == 9 )
> +    if ( argc >= 9 )
>             superpages = atoi(argv[8]);
>      else
>             superpages = !!hvm;
> +    if ( argc >= 10 )
> +           gid = strtoll(argv[9], NULL, 0);
> +    else
> +           gid = 0;
I don''t think you need to do anything more complex than pass
vm_gid_addr
as NULL here unless you are also going to patch xend.

I didn''t see anywhere which cranked the value on restore, it seems to
just propagate the value from the cfg file. Is that actually useful?

Does the user really need to be able to specify the initial value? Would
it not be easier to just generate a new value somehow when creating the
domain? No ones going to edit their cfg each time they start the vm.

Ian.

> -----Original Message-----
> From: Ian Campbell
> Sent: 01 December 2011 08:59
> To: Paul Durrant
> Cc: Konrad Rzeszutek Wilk; xen-devel@lists.xensource.com
> Subject: Re: [Xen-devel] [PATCH] Add code to track the address of
> the VM generation id buffer across a
> 
> On Thu, 2011-12-01 at 08:46 +0000, Paul Durrant wrote:
> > Konrad,
> >
> >   Did you see my previous patch set? The introductory comment was:
> 
> 
> I think that description belongs somewhere permanent, either in
> docs/misc or as a comment in an appropriate header.
> 
Good point. Perhaps I should stick the comment just above the device description
in the dsdt?

  Paul

On Thu, 2011-12-01 at 09:47 +0000, Paul Durrant wrote:
> > -----Original Message-----
> > From: Ian Campbell
> > Sent: 01 December 2011 08:59
> > To: Paul Durrant
> > Cc: Konrad Rzeszutek Wilk; xen-devel@lists.xensource.com
> > Subject: Re: [Xen-devel] [PATCH] Add code to track the address of
> > the VM generation id buffer across a
> > 
> > On Thu, 2011-12-01 at 08:46 +0000, Paul Durrant wrote:
> > > Konrad,
> > >
> > >   Did you see my previous patch set? The introductory comment
was:
> > 
> > 
> > I think that description belongs somewhere permanent, either in
> > docs/misc or as a comment in an appropriate header.
> > 
> 
> Good point. Perhaps I should stick the comment just above the device
description in the dsdt?
That would do I guess.

I guess more important would be the user facing toolstack specific
semantics/documentation i.e. the manpage.

Ian.

Would the following be sufficient?

  Paul

diff -r 62ff6a318c5d docs/man/xl.cfg.pod.5
--- a/docs/man/xl.cfg.pod.5     Wed Nov 30 16:59:58 2011 -0800
+++ b/docs/man/xl.cfg.pod.5     Thu Dec 01 11:52:58 2011 +0000
@@ -484,6 +484,12 @@ of Xen) within a Xen guest or to support
 which uses hardware virtualisation extensions (e.g. Windows XP
 compatibility mode on more modern Windows OS).

+=item B<generation_id=NUMBER>
+
+This value will be exposed inside the guest at an address which
+can be determined by evaluating the ADDR package of an ACPI device
+with _CID "VM_Gen_Counter".
+
 =back

 =head3 Guest Virtual Time Controls
diff -r 62ff6a318c5d tools/firmware/hvmloader/acpi/dsdt.asl
--- a/tools/firmware/hvmloader/acpi/dsdt.asl    Wed Nov 30 16:59:58 2011 -0800
+++ b/tools/firmware/hvmloader/acpi/dsdt.asl    Thu Dec 01 11:52:58 2011 +0000
@@ -398,6 +398,25 @@ DefinitionBlock ("DSDT.aml", "DSDT", 2,
                     })
                 }

+                /* VM Generation ID Device
+                 *
+                 * The basic requirements of this device are as follows:
+                 *
+                 * - It must be exposed somewhere in ACPI namespace with a _CID
of
+                 *   "VM_Gen_Counter".
+                 * - It must also include a _DDN of "VM_Gen_Counter".
+                 * - It must contain a _HID object but no particular value is
+                 *   required.
+                 * - It must expose a package called ADDR which evaluates to
two
+                 *   integers; the first being the low order 32-bits of a guest
+                 *   physical address (GPA), the second by the high order
32-bits of
+                 *   the GPA. This GPA is the address of an 8-byte aligned
8-byte
+                 *   buffer containing the VM generation ID.
+                 *   This buffer must not be in ranges supported as
AddressRangeMemory
+                 *   or AddressRangeACPI and must not be mapped by any PTE with
caching
+                 *   disabled. (See the code in
tools/firmware/hvmloader/acpi/build.c
+                 *   which determines the address and contents of the buffer).
+                 */
                 Device(VGID) {
                     Name(_HID, EisaID ("PNP0A06"))
                     Name(_UID, 0x00)
> -----Original Message-----
> From: Ian Campbell
> Sent: 01 December 2011 10:00
> To: Paul Durrant
> Cc: Konrad Rzeszutek Wilk; xen-devel@lists.xensource.com
> Subject: RE: [Xen-devel] [PATCH] Add code to track the address of
> the VM generation id buffer across a
> 
> On Thu, 2011-12-01 at 09:47 +0000, Paul Durrant wrote:
> > > -----Original Message-----
> > > From: Ian Campbell
> > > Sent: 01 December 2011 08:59
> > > To: Paul Durrant
> > > Cc: Konrad Rzeszutek Wilk; xen-devel@lists.xensource.com
> > > Subject: Re: [Xen-devel] [PATCH] Add code to track the address
> of
> > > the VM generation id buffer across a
> > >
> > > On Thu, 2011-12-01 at 08:46 +0000, Paul Durrant wrote:
> > > > Konrad,
> > > >
> > > >   Did you see my previous patch set? The introductory
comment
> was:
> > >
> > >
> > > I think that description belongs somewhere permanent, either in
> > > docs/misc or as a comment in an appropriate header.
> > >
> >
> > Good point. Perhaps I should stick the comment just above the
> device description in the dsdt?
> 
> That would do I guess.
> 
> I guess more important would be the user facing toolstack specific
> semantics/documentation i.e. the manpage.
> 
> Ian.
>

On Thu, 2011-12-01 at 11:54 +0000, Paul Durrant wrote:
> Would the following be sufficient?
> 
>   Paul
> 
> diff -r 62ff6a318c5d docs/man/xl.cfg.pod.5
> --- a/docs/man/xl.cfg.pod.5     Wed Nov 30 16:59:58 2011 -0800
> +++ b/docs/man/xl.cfg.pod.5     Thu Dec 01 11:52:58 2011 +0000
> @@ -484,6 +484,12 @@ of Xen) within a Xen guest or to support
>  which uses hardware virtualisation extensions (e.g. Windows XP
>  compatibility mode on more modern Windows OS).
> 
> +=item B<generation_id=NUMBER>
> +
> +This value will be exposed inside the guest at an address which
> +can be determined by evaluating the ADDR package of an ACPI device
> +with _CID "VM_Gen_Counter".
Belongs more in the "Support for Paravirtualisation of HVM Guests"
section, which is just below? The "Processor and Platform Features" is
more about things which are optional (at least in theory) on real
systems.

Since the semantics of the number itself are up to the toolstack and
this toolstack defers this requirement up to the user it should probably
also say something along the lines of:

        The semantics of this value are guest dependent and it is up to
        the user to ensure those semantics are met.

(even better would be to implement something meaningful in xl,
obviously)

Ian.
> +
>  =back
> 
>  =head3 Guest Virtual Time Controls
> diff -r 62ff6a318c5d tools/firmware/hvmloader/acpi/dsdt.asl
> --- a/tools/firmware/hvmloader/acpi/dsdt.asl    Wed Nov 30 16:59:58 2011
-0800
> +++ b/tools/firmware/hvmloader/acpi/dsdt.asl    Thu Dec 01 11:52:58 2011
+0000
> @@ -398,6 +398,25 @@ DefinitionBlock ("DSDT.aml",
"DSDT", 2,
>                      })
>                  }
> 
> +                /* VM Generation ID Device
> +                 *
> +                 * The basic requirements of this device are as follows:
> +                 *
> +                 * - It must be exposed somewhere in ACPI namespace with a
_CID of
> +                 *   "VM_Gen_Counter".
> +                 * - It must also include a _DDN of
"VM_Gen_Counter".
> +                 * - It must contain a _HID object but no particular value
is
> +                 *   required.
> +                 * - It must expose a package called ADDR which evaluates
to two
> +                 *   integers; the first being the low order 32-bits of a
guest
> +                 *   physical address (GPA), the second by the high order
32-bits of
> +                 *   the GPA. This GPA is the address of an 8-byte aligned
8-byte
> +                 *   buffer containing the VM generation ID.
> +                 *   This buffer must not be in ranges supported as
AddressRangeMemory
> +                 *   or AddressRangeACPI and must not be mapped by any PTE
with caching
> +                 *   disabled. (See the code in
tools/firmware/hvmloader/acpi/build.c
> +                 *   which determines the address and contents of the
buffer).
> +                 */
>                  Device(VGID) {
>                      Name(_HID, EisaID ("PNP0A06"))
>                      Name(_UID, 0x00)
> 
> > -----Original Message-----
> > From: Ian Campbell
> > Sent: 01 December 2011 10:00
> > To: Paul Durrant
> > Cc: Konrad Rzeszutek Wilk; xen-devel@lists.xensource.com
> > Subject: RE: [Xen-devel] [PATCH] Add code to track the address of
> > the VM generation id buffer across a
> > 
> > On Thu, 2011-12-01 at 09:47 +0000, Paul Durrant wrote:
> > > > -----Original Message-----
> > > > From: Ian Campbell
> > > > Sent: 01 December 2011 08:59
> > > > To: Paul Durrant
> > > > Cc: Konrad Rzeszutek Wilk; xen-devel@lists.xensource.com
> > > > Subject: Re: [Xen-devel] [PATCH] Add code to track the
address
> > of
> > > > the VM generation id buffer across a
> > > >
> > > > On Thu, 2011-12-01 at 08:46 +0000, Paul Durrant wrote:
> > > > > Konrad,
> > > > >
> > > > >   Did you see my previous patch set? The introductory
comment
> > was:
> > > >
> > > >
> > > > I think that description belongs somewhere permanent, either
in
> > > > docs/misc or as a comment in an appropriate header.
> > > >
> > >
> > > Good point. Perhaps I should stick the comment just above the
> > device description in the dsdt?
> > 
> > That would do I guess.
> > 
> > I guess more important would be the user facing toolstack specific
> > semantics/documentation i.e. the manpage.
> > 
> > Ian.
> > 
>

> -----Original Message-----
> From: Ian Campbell
> Sent: 01 December 2011 14:25
> To: Paul Durrant
> Cc: Konrad Rzeszutek Wilk; xen-devel@lists.xensource.com
> Subject: RE: [Xen-devel] [PATCH] Add code to track the address of
> the VM generation id buffer across a
> 
> On Thu, 2011-12-01 at 11:54 +0000, Paul Durrant wrote:
> > Would the following be sufficient?
> >
> >   Paul
> >
> > diff -r 62ff6a318c5d docs/man/xl.cfg.pod.5
> > --- a/docs/man/xl.cfg.pod.5     Wed Nov 30 16:59:58 2011 -0800
> > +++ b/docs/man/xl.cfg.pod.5     Thu Dec 01 11:52:58 2011 +0000
> > @@ -484,6 +484,12 @@ of Xen) within a Xen guest or to support
> which
> > uses hardware virtualisation extensions (e.g. Windows XP
> > compatibility mode on more modern Windows OS).
> >
> > +=item B<generation_id=NUMBER>
> > +
> > +This value will be exposed inside the guest at an address which
> can
> > +be determined by evaluating the ADDR package of an ACPI device
> with
> > +_CID "VM_Gen_Counter".
> 
> Belongs more in the "Support for Paravirtualisation of HVM
Guests"
> section, which is just below? The "Processor and Platform
Features"
> is more about things which are optional (at least in theory) on real
> systems.
> 
Ok.
> Since the semantics of the number itself are up to the toolstack and
> this toolstack defers this requirement up to the user it should
> probably also say something along the lines of:
> 
>         The semantics of this value are guest dependent and it is up
> to
>         the user to ensure those semantics are met.
> 
Ok, I''ll add something to that effect.

  Paul
> (even better would be to implement something meaningful in xl,
> obviously)
>

Konrad Rzeszutek Wilk writes ("Re: [Xen-devel] [PATCH] Add code to track
the address of the VM generation id buffer across
a"):
> So what is a generation id? What is the use-case for this?
Paul Durrant writes ("Re: [Xen-devel] [PATCH] Add code to track the address
of the VM generation id buffer across a"):
>   Did you see my previous patch set? The introductory comment was:
> 
> -----
> The following is a revised patch series to add support for a VM generation
ID virtual device for HVM guests.
> The basic requirements of this device are as follows:
This explains "what" but not "why".

Also, please don''t top post.

Ian.

> -----Original Message-----
> From: Ian Jackson [mailto:Ian.Jackson@eu.citrix.com]
> Sent: 01 December 2011 16:42
> To: Paul Durrant; Konrad Rzeszutek Wilk
> Cc: xen-devel@lists.xensource.com
> Subject: Re: [Xen-devel] [PATCH] Add code to track the address of
> the VM generation id buffer across a [and 1 more messages]
> 
> Konrad Rzeszutek Wilk writes ("Re: [Xen-devel] [PATCH] Add code to
> track the address of the VM generation id buffer across a"):
> > So what is a generation id? What is the use-case for this?
> 
> Paul Durrant writes ("Re: [Xen-devel] [PATCH] Add code to track the
> address of the VM generation id buffer across a"):
> >   Did you see my previous patch set? The introductory comment was:
> >
> > -----
> > The following is a revised patch series to add support for a VM
> generation ID virtual device for HVM guests.
> > The basic requirements of this device are as follows:
> 
> This explains "what" but not "why".
> 
OK. I already know there is one OS that consumes this interface and another
hypervisor that produces it but unfortunately I''m not at liberty to say
much more because I''m under NDA.
Hopefully a spec. will be forthcoming at some point.
> Also, please don''t top post.
> 
Sorry, I wasn''t aware that I was.

  Paul