The biggest subtlety here is there additional argument when op =SCHEDOP_shutdown
and reason == SHUTDOWN_suspend and its interpretation by
xc_domain_{save,restore}. Add some clarifying comments to libxc as well.
This patch moves some structs around but there is no functional change
other than improved documentation.
Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
---
v2: clarify code motion.
---
tools/libxc/xc_domain_restore.c | 10 ++++-
tools/libxc/xc_domain_save.c | 9 ++++-
xen/include/public/sched.h | 84 ++++++++++++++++++++++++++-------------
3 files changed, 72 insertions(+), 31 deletions(-)
diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index 3fe2b12..5541e73 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -1895,8 +1895,14 @@ int xc_domain_restore(xc_interface *xch, int io_fd,
uint32_t dom,
if ( i == 0 )
{
/*
- * Uncanonicalise the suspend-record frame number and poke
- * resume record.
+ * Uncanonicalise the start info frame number and poke in
+ * updated values into the start info itself.
+ *
+ * The start info MFN is the 3rd argument to the
+ * HYPERVISOR_sched_op hypercall when op==SCHEDOP_shutdown
+ * and reason==SHUTDOWN_suspend, it is canonicalised in
+ * xc_domain_save and therefore the PFN is found in the
+ * edx register.
*/
pfn = GET_FIELD(ctxt, user_regs.edx);
if ( (pfn >= dinfo->p2m_size) ||
diff --git a/tools/libxc/xc_domain_save.c b/tools/libxc/xc_domain_save.c
index c359649..f161472 100644
--- a/tools/libxc/xc_domain_save.c
+++ b/tools/libxc/xc_domain_save.c
@@ -1867,7 +1867,14 @@ int xc_domain_save(xc_interface *xch, int io_fd, uint32_t
dom, uint32_t max_iter
goto out;
}
- /* Canonicalise the suspend-record frame number. */
+ /*
+ * Canonicalise the start info frame number.
+ *
+ * The start info MFN is the 3rd argument to the
+ * HYPERVISOR_sched_op hypercall when op==SCHEDOP_shutdown and
+ * reason==SHUTDOWN_suspend and is therefore found in the edx
+ * register.
+ */
mfn = GET_FIELD(&ctxt, user_regs.edx);
if ( !MFN_IS_IN_PSEUDOPHYS_MAP(mfn) )
{
diff --git a/xen/include/public/sched.h b/xen/include/public/sched.h
index 7f87420..db5124a 100644
--- a/xen/include/public/sched.h
+++ b/xen/include/public/sched.h
@@ -1,8 +1,8 @@
/******************************************************************************
* sched.h
- *
+ *
* Scheduler state interactions
- *
+ *
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the
"Software"), to
* deal in the Software without restriction, including without limitation the
@@ -30,20 +30,33 @@
#include "event_channel.h"
/*
+ * `incontents 150 sched Guest Scheduler Operations
+ *
+ * The SCHEDOP interface provides mechanisms for a guest to interact
+ * with the scheduler, including yield, blocking and shutting itself
+ * down.
+ */
+
+/*
* The prototype for this hypercall is:
- * long sched_op(int cmd, void *arg)
+ * ` long HYPERVISOR_sched_op(enum sched_op cmd, void *arg, ...)
+ *
* @cmd == SCHEDOP_??? (scheduler operation).
* @arg == Operation-specific extra argument(s), as described below.
- *
+ * ... == Additional Operation-specific extra arguments, described below.
+ *
* Versions of Xen prior to 3.0.2 provided only the following legacy version
* of this hypercall, supporting only the commands yield, block and shutdown:
* long sched_op(int cmd, unsigned long arg)
* @cmd == SCHEDOP_??? (scheduler operation).
* @arg == 0 (SCHEDOP_yield and SCHEDOP_block)
* == SHUTDOWN_* code (SCHEDOP_shutdown)
- * This legacy version is available to new guests as sched_op_compat().
+ *
+ * This legacy version is available to new guests as:
+ * ` long HYPERVISOR_sched_op_compat(enum sched_op cmd, unsigned long arg)
*/
+/* ` enum sched_op { // SCHEDOP_* => struct sched_* */
/*
* Voluntarily yield the CPU.
* @arg == NULL.
@@ -61,59 +74,72 @@
/*
* Halt execution of this domain (all VCPUs) and notify the system controller.
- * @arg == pointer to sched_shutdown structure.
+ * @arg == pointer to sched_shutdown_t structure.
+ *
+ * If the sched_shutdown_t reason is SHUTDOWN_suspend then this
+ * hypercall takes an additional extra argument which should be the
+ * MFN of the guest''s start_info_t.
+ *
+ * In addition, which reason is SHUTDOWN_suspend this hypercall
+ * returns 1 if suspend was cancelled or the domain was merely
+ * checkpointed, and 0 if it is resuming in a new domain.
*/
#define SCHEDOP_shutdown 2
-struct sched_shutdown {
- unsigned int reason; /* SHUTDOWN_* */
-};
-typedef struct sched_shutdown sched_shutdown_t;
-DEFINE_XEN_GUEST_HANDLE(sched_shutdown_t);
/*
* Poll a set of event-channel ports. Return when one or more are pending. An
* optional timeout may be specified.
- * @arg == pointer to sched_poll structure.
+ * @arg == pointer to sched_poll_t structure.
*/
#define SCHEDOP_poll 3
-struct sched_poll {
- XEN_GUEST_HANDLE(evtchn_port_t) ports;
- unsigned int nr_ports;
- uint64_t timeout;
-};
-typedef struct sched_poll sched_poll_t;
-DEFINE_XEN_GUEST_HANDLE(sched_poll_t);
/*
* Declare a shutdown for another domain. The main use of this function is
* in interpreting shutdown requests and reasons for fully-virtualized
* domains. A para-virtualized domain may use SCHEDOP_shutdown directly.
- * @arg == pointer to sched_remote_shutdown structure.
+ * @arg == pointer to sched_remote_shutdown_t structure.
*/
#define SCHEDOP_remote_shutdown 4
-struct sched_remote_shutdown {
- domid_t domain_id; /* Remote domain ID */
- unsigned int reason; /* SHUTDOWN_xxx reason */
-};
-typedef struct sched_remote_shutdown sched_remote_shutdown_t;
-DEFINE_XEN_GUEST_HANDLE(sched_remote_shutdown_t);
/*
* Latch a shutdown code, so that when the domain later shuts down it
* reports this code to the control tools.
- * @arg == as for SCHEDOP_shutdown.
+ * @arg == sched_shutdown_t, as for SCHEDOP_shutdown.
*/
#define SCHEDOP_shutdown_code 5
/*
* Setup, poke and destroy a domain watchdog timer.
- * @arg == pointer to sched_watchdog structure.
+ * @arg == pointer to sched_watchdog_t structure.
* With id == 0, setup a domain watchdog timer to cause domain shutdown
* after timeout, returns watchdog id.
* With id != 0 and timeout == 0, destroy domain watchdog timer.
* With id != 0 and timeout != 0, poke watchdog timer and set new timeout.
*/
#define SCHEDOP_watchdog 6
+/* ` } */
+
+struct sched_shutdown {
+ unsigned int reason; /* SHUTDOWN_* => enum sched_shutdown_reason */
+};
+typedef struct sched_shutdown sched_shutdown_t;
+DEFINE_XEN_GUEST_HANDLE(sched_shutdown_t);
+
+struct sched_poll {
+ XEN_GUEST_HANDLE(evtchn_port_t) ports;
+ unsigned int nr_ports;
+ uint64_t timeout;
+};
+typedef struct sched_poll sched_poll_t;
+DEFINE_XEN_GUEST_HANDLE(sched_poll_t);
+
+struct sched_remote_shutdown {
+ domid_t domain_id; /* Remote domain ID */
+ unsigned int reason; /* SHUTDOWN_* => enum sched_shutdown_reason
*/
+};
+typedef struct sched_remote_shutdown sched_remote_shutdown_t;
+DEFINE_XEN_GUEST_HANDLE(sched_remote_shutdown_t);
+
struct sched_watchdog {
uint32_t id; /* watchdog ID */
uint32_t timeout; /* timeout */
@@ -126,11 +152,13 @@ DEFINE_XEN_GUEST_HANDLE(sched_watchdog_t);
* software to determine the appropriate action. For the most part, Xen does
* not care about the shutdown code.
*/
+/* ` enum sched_shutdown_reason { */
#define SHUTDOWN_poweroff 0 /* Domain exited normally. Clean up and kill. */
#define SHUTDOWN_reboot 1 /* Clean up, kill, and then restart. */
#define SHUTDOWN_suspend 2 /* Clean up, save suspend info, kill. */
#define SHUTDOWN_crash 3 /* Tell controller we''ve crashed.
*/
#define SHUTDOWN_watchdog 4 /* Restart because watchdog time expired. */
+/* ` } */
#endif /* __XEN_PUBLIC_SCHED_H__ */
--
1.7.2.5