<stefano.stabellini@eu.citrix.com>
2011-Jul-26 16:55 UTC
[Xen-devel] [PATCH] xen: modify kernel mappings corresponding to granted pages
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
If we want to use granted pages for AIO, changing the mappings of a user
vma and the corresponding p2m is not enough, we also need to update the
kernel mappings accordingly.
On x86_64 it is easy, we can issue another HYPERVISOR_grant_table_op
right away in m2p_add_override. We can remove the mappings using another
HYPERVISOR_grant_table_op in m2p_remove_override.
On x86_32 it is more difficult because the pages are highmem pages and
therefore we need to catch the set_pte that tries to map a granted page
and issue an HYPERVISOR_grant_table_op instead.
Same thing for unmapping them: we need to catch the pte clear or the
set_pte that try to unmap a granted page and issue an
HYPERVISOR_grant_table_op.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
arch/x86/include/asm/xen/page.h | 5 ++-
arch/x86/xen/mmu.c | 68 +++++++++++++++++++++++++++++++++++++++
arch/x86/xen/p2m.c | 47 ++++++++++++++++++++------
drivers/xen/gntdev.c | 27 +++++++++++++++-
drivers/xen/grant-table.c | 4 +-
include/xen/grant_table.h | 1 +
6 files changed, 137 insertions(+), 15 deletions(-)
diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h
index 64a619d..ec7bbfb 100644
--- a/arch/x86/include/asm/xen/page.h
+++ b/arch/x86/include/asm/xen/page.h
@@ -12,6 +12,7 @@
#include <asm/pgtable.h>
#include <xen/interface/xen.h>
+#include <xen/grant_table.h>
#include <xen/features.h>
/* Xen machine address */
@@ -31,8 +32,10 @@ typedef struct xpaddr {
#define INVALID_P2M_ENTRY (~0UL)
#define FOREIGN_FRAME_BIT (1UL<<(BITS_PER_LONG-1))
#define IDENTITY_FRAME_BIT (1UL<<(BITS_PER_LONG-2))
+#define GRANT_FRAME_BIT (1UL<<(BITS_PER_LONG-3))
#define FOREIGN_FRAME(m) ((m) | FOREIGN_FRAME_BIT)
#define IDENTITY_FRAME(m) ((m) | IDENTITY_FRAME_BIT)
+#define GRANT_FRAME(m) ((m) | GRANT_FRAME_BIT)
/* Maximum amount of memory we can handle in a domain in pages */
#define MAX_DOMAIN_PAGES \
@@ -48,7 +51,7 @@ extern unsigned long set_phys_range_identity(unsigned long
pfn_s,
unsigned long pfn_e);
extern int m2p_add_override(unsigned long mfn, struct page *page,
- bool clear_pte);
+ struct gnttab_map_grant_ref *kmap_op);
extern int m2p_remove_override(struct page *page, bool clear_pte);
extern struct page *m2p_find_override(unsigned long mfn);
extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long
pfn);
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 4e37a7c0..13f20d8 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -282,8 +282,70 @@ static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval)
return true;
}
+#ifdef CONFIG_HIGHMEM
+static int xen_unmap_granted_page(pte_t *ptep)
+{
+ unsigned long mfn;
+ struct page *page;
+
+ if (pte_flags(*ptep) & _PAGE_USER)
+ return 1;
+ mfn = (ptep->pte & PTE_PFN_MASK) >> PAGE_SHIFT;
+ page = m2p_find_override(mfn);
+ if (page != NULL && (page->private & GRANT_FRAME_BIT)) {
+ int ret;
+ struct gnttab_unmap_grant_ref kunmap_op;
+ struct gnttab_map_grant_ref *kmap_op + (struct gnttab_map_grant_ref *)
page->index;
+ kunmap_op.host_addr = kmap_op->host_addr;
+ kunmap_op.handle = kmap_op->handle;
+ kunmap_op.dev_bus_addr = 0;
+ ret = HYPERVISOR_grant_table_op(
+ GNTTABOP_unmap_grant_ref, &kunmap_op, 1);
+ WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, failed to "
+ "modify kernel mappings", page_to_pfn(page), mfn);
+ return ret;
+ }
+ return 1;
+}
+#endif
+
static void xen_set_pte(pte_t *ptep, pte_t pteval)
{
+#ifdef CONFIG_HIGHMEM
+ if (!(pte_flags(pteval) & _PAGE_USER)) {
+ int ret;
+ struct page *page;
+ unsigned long mfn = (pteval.pte & PTE_PFN_MASK) >> PAGE_SHIFT;
+ page = m2p_find_override(mfn);
+ /*
+ * if this is a granted page we need to use a grant table
+ * hypercall to map it instead
+ */
+ if (page != NULL && (page->private & GRANT_FRAME_BIT)) {
+ struct gnttab_map_grant_ref *kmap_op + (struct gnttab_map_grant_ref *)
page->index;
+ unsigned long old_mfn = kmap_op->dev_bus_addr;
+ kmap_op->host_addr + arbitrary_virt_to_machine(ptep).maddr;
+ kmap_op->dev_bus_addr = 0;
+ ret = HYPERVISOR_grant_table_op(
+ GNTTABOP_map_grant_ref, kmap_op, 1);
+ WARN(ret, "xen_set_pte: pfn %lx mfn %lx, failed to "
+ "modify kernel mappings",
+ page_to_pfn(page), mfn);
+ kmap_op->dev_bus_addr = old_mfn;
+ return;
+ }
+ /*
+ * even if it is not a granted page, the old page we are about
+ * to overwrite could be a granted page and in that case we need
+ * to unmap it using a grant table hypercall
+ */
+ xen_unmap_granted_page(ptep);
+ }
+#endif
+
if (!xen_batched_set_pte(ptep, pteval))
native_set_pte(ptep, pteval);
}
@@ -548,6 +610,12 @@ static void xen_set_pte_atomic(pte_t *ptep, pte_t pte)
static void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t
*ptep)
{
+ /*
+ * check if this is a granted page and unmap it using a grant table
+ * hypercall in that case
+ */
+ if (!xen_unmap_granted_page(ptep))
+ return;
if (!xen_batched_set_pte(ptep, native_make_pte(0)))
native_pte_clear(mm, addr, ptep);
}
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 58efeb9..1c4d2b5 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -161,6 +161,7 @@
#include <asm/xen/page.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
+#include <xen/grant_table.h>
#include "xen-ops.h"
@@ -676,7 +677,8 @@ static unsigned long mfn_hash(unsigned long mfn)
}
/* Add an MFN override for a particular page */
-int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte)
+int m2p_add_override(unsigned long mfn, struct page *page,
+ struct gnttab_map_grant_ref *kmap_op)
{
unsigned long flags;
unsigned long pfn;
@@ -699,9 +701,18 @@ int m2p_add_override(unsigned long mfn, struct page *page,
bool clear_pte)
if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn))))
return -ENOMEM;
- if (clear_pte && !PageHighMem(page))
- /* Just zap old mapping for now */
- pte_clear(&init_mm, address, ptep);
+ if (kmap_op != NULL) {
+ if (!PageHighMem(page)) {
+ int ret = HYPERVISOR_grant_table_op(
+ GNTTABOP_map_grant_ref, kmap_op, 1);
+ WARN(ret, "m2p_add_override: pfn %lx mfn %lx, "
+ "failed to modify kernel mappings", pfn, mfn);
+ }
+ page->private |= GRANT_FRAME_BIT;
+ /* let''s use dev_bus_addr to record the old mfn instead */
+ kmap_op->dev_bus_addr = page->index;
+ page->index = (unsigned long) kmap_op;
+ }
spin_lock_irqsave(&m2p_override_lock, flags);
list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
spin_unlock_irqrestore(&m2p_override_lock, flags);
@@ -735,13 +746,27 @@ int m2p_remove_override(struct page *page, bool clear_pte)
spin_lock_irqsave(&m2p_override_lock, flags);
list_del(&page->lru);
spin_unlock_irqrestore(&m2p_override_lock, flags);
- set_phys_to_machine(pfn, page->index);
- if (clear_pte && !PageHighMem(page))
- set_pte_at(&init_mm, address, ptep,
- pfn_pte(pfn, PAGE_KERNEL));
- /* No tlb flush necessary because the caller already
- * left the pte unmapped. */
+ if (clear_pte) {
+ struct gnttab_map_grant_ref *map_op + (struct gnttab_map_grant_ref *)
page->index;
+ set_phys_to_machine(pfn, map_op->dev_bus_addr);
+ if (!PageHighMem(page)) {
+ int ret;
+ struct gnttab_unmap_grant_ref unmap_op;
+ unmap_op.host_addr = map_op->host_addr;
+ unmap_op.handle = map_op->handle;
+ unmap_op.dev_bus_addr = 0;
+ ret = HYPERVISOR_grant_table_op(
+ GNTTABOP_unmap_grant_ref, &unmap_op, 1);
+ WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, "
+ "failed to modify kernel mappings", pfn, mfn);
+ set_pte_at(&init_mm, address, ptep,
+ pfn_pte(pfn, PAGE_KERNEL));
+ __flush_tlb_single(address);
+ }
+ } else
+ set_phys_to_machine(pfn, page->index);
return 0;
}
@@ -758,7 +783,7 @@ struct page *m2p_find_override(unsigned long mfn)
spin_lock_irqsave(&m2p_override_lock, flags);
list_for_each_entry(p, bucket, lru) {
- if (p->private == mfn) {
+ if ((p->private & (~GRANT_FRAME_BIT)) == mfn) {
ret = p;
break;
}
diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
index f914b26..ca41772 100644
--- a/drivers/xen/gntdev.c
+++ b/drivers/xen/gntdev.c
@@ -83,6 +83,7 @@ struct grant_map {
struct ioctl_gntdev_grant_ref *grants;
struct gnttab_map_grant_ref *map_ops;
struct gnttab_unmap_grant_ref *unmap_ops;
+ struct gnttab_map_grant_ref *kmap_ops;
struct page **pages;
};
@@ -116,10 +117,12 @@ static struct grant_map *gntdev_alloc_map(struct
gntdev_priv *priv, int count)
add->grants = kzalloc(sizeof(add->grants[0]) * count, GFP_KERNEL);
add->map_ops = kzalloc(sizeof(add->map_ops[0]) * count, GFP_KERNEL);
add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL);
+ add->kmap_ops = kzalloc(sizeof(add->kmap_ops[0]) * count, GFP_KERNEL);
add->pages = kzalloc(sizeof(add->pages[0]) * count, GFP_KERNEL);
if (NULL == add->grants ||
NULL == add->map_ops ||
NULL == add->unmap_ops ||
+ NULL == add->kmap_ops ||
NULL == add->pages)
goto err;
@@ -129,6 +132,7 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv
*priv, int count)
for (i = 0; i < count; i++) {
add->map_ops[i].handle = -1;
add->unmap_ops[i].handle = -1;
+ add->kmap_ops[i].handle = -1;
}
add->index = 0;
@@ -142,6 +146,7 @@ err:
kfree(add->grants);
kfree(add->map_ops);
kfree(add->unmap_ops);
+ kfree(add->kmap_ops);
kfree(add);
return NULL;
}
@@ -243,10 +248,30 @@ static int map_grant_pages(struct grant_map *map)
gnttab_set_unmap_op(&map->unmap_ops[i], addr,
map->flags, -1 /* handle */);
}
+ } else {
+ for (i = 0; i < map->count; i++) {
+ unsigned level;
+ unsigned long address = (unsigned long)
+ pfn_to_kaddr(page_to_pfn(map->pages[i]));
+ pte_t *ptep;
+ u64 pte_maddr = 0;
+ if (!PageHighMem(map->pages[i])) {
+ ptep = lookup_address(address, &level);
+ pte_maddr + arbitrary_virt_to_machine(ptep).maddr;
+ }
+ gnttab_set_map_op(&map->kmap_ops[i], pte_maddr,
+ map->flags |
+ GNTMAP_host_map |
+ GNTMAP_contains_pte,
+ map->grants[i].ref,
+ map->grants[i].domid);
+ }
}
pr_debug("map %d+%d\n", map->index, map->count);
- err = gnttab_map_refs(map->map_ops, map->pages, map->count);
+ err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL,
+ map->pages, map->count);
if (err)
return err;
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index fd725cd..1e8669a 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -448,6 +448,7 @@ unsigned int gnttab_max_grant_frames(void)
EXPORT_SYMBOL_GPL(gnttab_max_grant_frames);
int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count)
{
int i, ret;
@@ -488,8 +489,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
*/
return -EOPNOTSUPP;
}
- ret = m2p_add_override(mfn, pages[i],
- map_ops[i].flags & GNTMAP_contains_pte);
+ ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]);
if (ret)
return ret;
}
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index b1fab6b..6b99bfb 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -156,6 +156,7 @@ unsigned int gnttab_max_grant_frames(void);
#define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr))
int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops,
+ struct gnttab_map_grant_ref *kmap_ops,
struct page **pages, unsigned int count);
int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops,
struct page **pages, unsigned int count);
--
1.7.2.3
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel
Konrad Rzeszutek Wilk
2011-Aug-09 02:34 UTC
[Xen-devel] Re: [PATCH] xen: modify kernel mappings corresponding to granted pages
On Tue, Jul 26, 2011 at 05:55:45PM +0100, stefano.stabellini@eu.citrix.com wrote:> From: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > If we want to use granted pages for AIO, changing the mappings of a user > vma and the corresponding p2m is not enough, we also need to update the > kernel mappings accordingly. > On x86_64 it is easy, we can issue another HYPERVISOR_grant_table_op > right away in m2p_add_override. We can remove the mappings using another > HYPERVISOR_grant_table_op in m2p_remove_override. > On x86_32 it is more difficult because the pages are highmem pages and > therefore we need to catch the set_pte that tries to map a granted page > and issue an HYPERVISOR_grant_table_op instead. > Same thing for unmapping them: we need to catch the pte clear or the > set_pte that try to unmap a granted page and issue an > HYPERVISOR_grant_table_op.So I hadn''t looked at this in detail, but I wonder if we can use the MULTIcall for this? It looks like we need to do two hypercalls so why not batch it? And while we are it - we could change the MMU ops to only do this on initial domain and for the domU case do the old mechanism? In essence adding two variants of the xen_set_pte - domU and dom0? .. And we should get rid of the debug one (xen_set_pte_debug) - it has helped a bit but I don''t think anybody is using it except me.> > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > --- > arch/x86/include/asm/xen/page.h | 5 ++- > arch/x86/xen/mmu.c | 68 +++++++++++++++++++++++++++++++++++++++ > arch/x86/xen/p2m.c | 47 ++++++++++++++++++++------ > drivers/xen/gntdev.c | 27 +++++++++++++++- > drivers/xen/grant-table.c | 4 +- > include/xen/grant_table.h | 1 + > 6 files changed, 137 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h > index 64a619d..ec7bbfb 100644 > --- a/arch/x86/include/asm/xen/page.h > +++ b/arch/x86/include/asm/xen/page.h > @@ -12,6 +12,7 @@ > #include <asm/pgtable.h> > > #include <xen/interface/xen.h> > +#include <xen/grant_table.h> > #include <xen/features.h> > > /* Xen machine address */ > @@ -31,8 +32,10 @@ typedef struct xpaddr { > #define INVALID_P2M_ENTRY (~0UL) > #define FOREIGN_FRAME_BIT (1UL<<(BITS_PER_LONG-1)) > #define IDENTITY_FRAME_BIT (1UL<<(BITS_PER_LONG-2)) > +#define GRANT_FRAME_BIT (1UL<<(BITS_PER_LONG-3)) > #define FOREIGN_FRAME(m) ((m) | FOREIGN_FRAME_BIT) > #define IDENTITY_FRAME(m) ((m) | IDENTITY_FRAME_BIT) > +#define GRANT_FRAME(m) ((m) | GRANT_FRAME_BIT) > > /* Maximum amount of memory we can handle in a domain in pages */ > #define MAX_DOMAIN_PAGES \ > @@ -48,7 +51,7 @@ extern unsigned long set_phys_range_identity(unsigned long pfn_s, > unsigned long pfn_e); > > extern int m2p_add_override(unsigned long mfn, struct page *page, > - bool clear_pte); > + struct gnttab_map_grant_ref *kmap_op); > extern int m2p_remove_override(struct page *page, bool clear_pte); > extern struct page *m2p_find_override(unsigned long mfn); > extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn); > diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c > index 4e37a7c0..13f20d8 100644 > --- a/arch/x86/xen/mmu.c > +++ b/arch/x86/xen/mmu.c > @@ -282,8 +282,70 @@ static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval) > return true; > } > > +#ifdef CONFIG_HIGHMEM > +static int xen_unmap_granted_page(pte_t *ptep) > +{ > + unsigned long mfn; > + struct page *page; > + > + if (pte_flags(*ptep) & _PAGE_USER) > + return 1; > + mfn = (ptep->pte & PTE_PFN_MASK) >> PAGE_SHIFT; > + page = m2p_find_override(mfn); > + if (page != NULL && (page->private & GRANT_FRAME_BIT)) { > + int ret; > + struct gnttab_unmap_grant_ref kunmap_op; > + struct gnttab_map_grant_ref *kmap_op > + (struct gnttab_map_grant_ref *) page->index; > + kunmap_op.host_addr = kmap_op->host_addr; > + kunmap_op.handle = kmap_op->handle; > + kunmap_op.dev_bus_addr = 0; > + ret = HYPERVISOR_grant_table_op( > + GNTTABOP_unmap_grant_ref, &kunmap_op, 1); > + WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, failed to " > + "modify kernel mappings", page_to_pfn(page), mfn); > + return ret; > + } > + return 1; > +} > +#endif > + > static void xen_set_pte(pte_t *ptep, pte_t pteval) > { > +#ifdef CONFIG_HIGHMEM > + if (!(pte_flags(pteval) & _PAGE_USER)) { > + int ret; > + struct page *page; > + unsigned long mfn = (pteval.pte & PTE_PFN_MASK) >> PAGE_SHIFT; > + page = m2p_find_override(mfn); > + /* > + * if this is a granted page we need to use a grant table > + * hypercall to map it instead > + */ > + if (page != NULL && (page->private & GRANT_FRAME_BIT)) { > + struct gnttab_map_grant_ref *kmap_op > + (struct gnttab_map_grant_ref *) page->index; > + unsigned long old_mfn = kmap_op->dev_bus_addr; > + kmap_op->host_addr > + arbitrary_virt_to_machine(ptep).maddr; > + kmap_op->dev_bus_addr = 0; > + ret = HYPERVISOR_grant_table_op( > + GNTTABOP_map_grant_ref, kmap_op, 1); > + WARN(ret, "xen_set_pte: pfn %lx mfn %lx, failed to " > + "modify kernel mappings", > + page_to_pfn(page), mfn); > + kmap_op->dev_bus_addr = old_mfn; > + return; > + } > + /* > + * even if it is not a granted page, the old page we are about > + * to overwrite could be a granted page and in that case we need > + * to unmap it using a grant table hypercall > + */ > + xen_unmap_granted_page(ptep); > + } > +#endif > + > if (!xen_batched_set_pte(ptep, pteval)) > native_set_pte(ptep, pteval); > } > @@ -548,6 +610,12 @@ static void xen_set_pte_atomic(pte_t *ptep, pte_t pte) > > static void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) > { > + /* > + * check if this is a granted page and unmap it using a grant table > + * hypercall in that case > + */ > + if (!xen_unmap_granted_page(ptep)) > + return; > if (!xen_batched_set_pte(ptep, native_make_pte(0))) > native_pte_clear(mm, addr, ptep); > } > diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c > index 58efeb9..1c4d2b5 100644 > --- a/arch/x86/xen/p2m.c > +++ b/arch/x86/xen/p2m.c > @@ -161,6 +161,7 @@ > #include <asm/xen/page.h> > #include <asm/xen/hypercall.h> > #include <asm/xen/hypervisor.h> > +#include <xen/grant_table.h> > > #include "xen-ops.h" > > @@ -676,7 +677,8 @@ static unsigned long mfn_hash(unsigned long mfn) > } > > /* Add an MFN override for a particular page */ > -int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte) > +int m2p_add_override(unsigned long mfn, struct page *page, > + struct gnttab_map_grant_ref *kmap_op) > { > unsigned long flags; > unsigned long pfn; > @@ -699,9 +701,18 @@ int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte) > if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) > return -ENOMEM; > > - if (clear_pte && !PageHighMem(page)) > - /* Just zap old mapping for now */ > - pte_clear(&init_mm, address, ptep); > + if (kmap_op != NULL) { > + if (!PageHighMem(page)) { > + int ret = HYPERVISOR_grant_table_op( > + GNTTABOP_map_grant_ref, kmap_op, 1); > + WARN(ret, "m2p_add_override: pfn %lx mfn %lx, " > + "failed to modify kernel mappings", pfn, mfn); > + } > + page->private |= GRANT_FRAME_BIT; > + /* let''s use dev_bus_addr to record the old mfn instead */ > + kmap_op->dev_bus_addr = page->index; > + page->index = (unsigned long) kmap_op; > + } > spin_lock_irqsave(&m2p_override_lock, flags); > list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); > spin_unlock_irqrestore(&m2p_override_lock, flags); > @@ -735,13 +746,27 @@ int m2p_remove_override(struct page *page, bool clear_pte) > spin_lock_irqsave(&m2p_override_lock, flags); > list_del(&page->lru); > spin_unlock_irqrestore(&m2p_override_lock, flags); > - set_phys_to_machine(pfn, page->index); > > - if (clear_pte && !PageHighMem(page)) > - set_pte_at(&init_mm, address, ptep, > - pfn_pte(pfn, PAGE_KERNEL)); > - /* No tlb flush necessary because the caller already > - * left the pte unmapped. */ > + if (clear_pte) { > + struct gnttab_map_grant_ref *map_op > + (struct gnttab_map_grant_ref *) page->index; > + set_phys_to_machine(pfn, map_op->dev_bus_addr); > + if (!PageHighMem(page)) { > + int ret; > + struct gnttab_unmap_grant_ref unmap_op; > + unmap_op.host_addr = map_op->host_addr; > + unmap_op.handle = map_op->handle; > + unmap_op.dev_bus_addr = 0; > + ret = HYPERVISOR_grant_table_op( > + GNTTABOP_unmap_grant_ref, &unmap_op, 1); > + WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, " > + "failed to modify kernel mappings", pfn, mfn); > + set_pte_at(&init_mm, address, ptep, > + pfn_pte(pfn, PAGE_KERNEL)); > + __flush_tlb_single(address); > + } > + } else > + set_phys_to_machine(pfn, page->index); > > return 0; > } > @@ -758,7 +783,7 @@ struct page *m2p_find_override(unsigned long mfn) > spin_lock_irqsave(&m2p_override_lock, flags); > > list_for_each_entry(p, bucket, lru) { > - if (p->private == mfn) { > + if ((p->private & (~GRANT_FRAME_BIT)) == mfn) { > ret = p; > break; > } > diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c > index f914b26..ca41772 100644 > --- a/drivers/xen/gntdev.c > +++ b/drivers/xen/gntdev.c > @@ -83,6 +83,7 @@ struct grant_map { > struct ioctl_gntdev_grant_ref *grants; > struct gnttab_map_grant_ref *map_ops; > struct gnttab_unmap_grant_ref *unmap_ops; > + struct gnttab_map_grant_ref *kmap_ops; > struct page **pages; > }; > > @@ -116,10 +117,12 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) > add->grants = kzalloc(sizeof(add->grants[0]) * count, GFP_KERNEL); > add->map_ops = kzalloc(sizeof(add->map_ops[0]) * count, GFP_KERNEL); > add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL); > + add->kmap_ops = kzalloc(sizeof(add->kmap_ops[0]) * count, GFP_KERNEL); > add->pages = kzalloc(sizeof(add->pages[0]) * count, GFP_KERNEL); > if (NULL == add->grants || > NULL == add->map_ops || > NULL == add->unmap_ops || > + NULL == add->kmap_ops || > NULL == add->pages) > goto err; > > @@ -129,6 +132,7 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) > for (i = 0; i < count; i++) { > add->map_ops[i].handle = -1; > add->unmap_ops[i].handle = -1; > + add->kmap_ops[i].handle = -1; > } > > add->index = 0; > @@ -142,6 +146,7 @@ err: > kfree(add->grants); > kfree(add->map_ops); > kfree(add->unmap_ops); > + kfree(add->kmap_ops); > kfree(add); > return NULL; > } > @@ -243,10 +248,30 @@ static int map_grant_pages(struct grant_map *map) > gnttab_set_unmap_op(&map->unmap_ops[i], addr, > map->flags, -1 /* handle */); > } > + } else { > + for (i = 0; i < map->count; i++) { > + unsigned level; > + unsigned long address = (unsigned long) > + pfn_to_kaddr(page_to_pfn(map->pages[i])); > + pte_t *ptep; > + u64 pte_maddr = 0; > + if (!PageHighMem(map->pages[i])) { > + ptep = lookup_address(address, &level); > + pte_maddr > + arbitrary_virt_to_machine(ptep).maddr; > + } > + gnttab_set_map_op(&map->kmap_ops[i], pte_maddr, > + map->flags | > + GNTMAP_host_map | > + GNTMAP_contains_pte, > + map->grants[i].ref, > + map->grants[i].domid); > + } > } > > pr_debug("map %d+%d\n", map->index, map->count); > - err = gnttab_map_refs(map->map_ops, map->pages, map->count); > + err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, > + map->pages, map->count); > if (err) > return err; > > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > index fd725cd..1e8669a 100644 > --- a/drivers/xen/grant-table.c > +++ b/drivers/xen/grant-table.c > @@ -448,6 +448,7 @@ unsigned int gnttab_max_grant_frames(void) > EXPORT_SYMBOL_GPL(gnttab_max_grant_frames); > > int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > + struct gnttab_map_grant_ref *kmap_ops, > struct page **pages, unsigned int count) > { > int i, ret; > @@ -488,8 +489,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > */ > return -EOPNOTSUPP; > } > - ret = m2p_add_override(mfn, pages[i], > - map_ops[i].flags & GNTMAP_contains_pte); > + ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]); > if (ret) > return ret; > } > diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h > index b1fab6b..6b99bfb 100644 > --- a/include/xen/grant_table.h > +++ b/include/xen/grant_table.h > @@ -156,6 +156,7 @@ unsigned int gnttab_max_grant_frames(void); > #define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr)) > > int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > + struct gnttab_map_grant_ref *kmap_ops, > struct page **pages, unsigned int count); > int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, > struct page **pages, unsigned int count); > -- > 1.7.2.3_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Ian Campbell
2011-Aug-09 11:08 UTC
[Xen-devel] Re: [PATCH] xen: modify kernel mappings corresponding to granted pages
On Tue, 2011-07-26 at 17:55 +0100, stefano.stabellini@eu.citrix.com wrote:> From: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > If we want to use granted pages for AIO, changing the mappings of a user > vma and the corresponding p2m is not enough, we also need to update the > kernel mappings accordingly. > On x86_64 it is easy, we can issue another HYPERVISOR_grant_table_op > right away in m2p_add_override. We can remove the mappings using another > HYPERVISOR_grant_table_op in m2p_remove_override. > On x86_32 it is more difficult because the pages are highmem pages and > therefore we need to catch the set_pte that tries to map a granted page > and issue an HYPERVISOR_grant_table_op instead. > Same thing for unmapping them: we need to catch the pte clear or the > set_pte that try to unmap a granted page and issue an > HYPERVISOR_grant_table_op. > > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > --- > arch/x86/include/asm/xen/page.h | 5 ++- > arch/x86/xen/mmu.c | 68 +++++++++++++++++++++++++++++++++++++++ > arch/x86/xen/p2m.c | 47 ++++++++++++++++++++------ > drivers/xen/gntdev.c | 27 +++++++++++++++- > drivers/xen/grant-table.c | 4 +- > include/xen/grant_table.h | 1 + > 6 files changed, 137 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h > index 64a619d..ec7bbfb 100644 > --- a/arch/x86/include/asm/xen/page.h > +++ b/arch/x86/include/asm/xen/page.h > @@ -12,6 +12,7 @@ > #include <asm/pgtable.h> > > #include <xen/interface/xen.h> > +#include <xen/grant_table.h> > #include <xen/features.h> > > /* Xen machine address */ > @@ -31,8 +32,10 @@ typedef struct xpaddr { > #define INVALID_P2M_ENTRY (~0UL) > #define FOREIGN_FRAME_BIT (1UL<<(BITS_PER_LONG-1)) > #define IDENTITY_FRAME_BIT (1UL<<(BITS_PER_LONG-2)) > +#define GRANT_FRAME_BIT (1UL<<(BITS_PER_LONG-3))We need to be a bit careful about stealing more bits from the top of the MFN space, especially on 32 bit. Stealing the top three bits of a 32 bit MFN leaves a total (host) address space of 2^(29+12) == 2TB, which seems large today but... To be honest even the current stealing the top 2 bits (==8TB) seems a bit shaky for the not too distant future... I''m not sure what the alternatives are though. Perhaps we can switch FOREIGN_FRAME_BIT to SOMETHING_SPECIAL_BIT (with a better name ;-)) and do a secondary lookup based on that? That might be too heavy weight for FOREIGN and IDENTITY lookups? But for the grant frame bits we are already manipulating a hashtable too aren''t we? The secondary lookup could be PFN indexed so wouldn''t necessarily need to scale to TB sizes, probably a bitmap would do? Alternatively perhaps we can reuse the other 31 bits when the SOMETHING_SPECIAL_BIT is set to indicate what kind of special? e.g. FOREIGN == 0x80000000, IDENTITY == 0x80000001, GRANT == 0x80000002 etc? Might interact strangely with the save/restore protocol (ISTR Konrad investigated that when he added IDENTITY_FRAME_BIT but don''t recall the result). Ian.> #define FOREIGN_FRAME(m) ((m) | FOREIGN_FRAME_BIT) > #define IDENTITY_FRAME(m) ((m) | IDENTITY_FRAME_BIT) > +#define GRANT_FRAME(m) ((m) | GRANT_FRAME_BIT) > > /* Maximum amount of memory we can handle in a domain in pages */ > #define MAX_DOMAIN_PAGES \ > @@ -48,7 +51,7 @@ extern unsigned long set_phys_range_identity(unsigned long pfn_s, > unsigned long pfn_e); > > extern int m2p_add_override(unsigned long mfn, struct page *page, > - bool clear_pte); > + struct gnttab_map_grant_ref *kmap_op); > extern int m2p_remove_override(struct page *page, bool clear_pte); > extern struct page *m2p_find_override(unsigned long mfn); > extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn); > diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c > index 4e37a7c0..13f20d8 100644 > --- a/arch/x86/xen/mmu.c > +++ b/arch/x86/xen/mmu.c > @@ -282,8 +282,70 @@ static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval) > return true; > } > > +#ifdef CONFIG_HIGHMEM > +static int xen_unmap_granted_page(pte_t *ptep) > +{ > + unsigned long mfn; > + struct page *page; > + > + if (pte_flags(*ptep) & _PAGE_USER) > + return 1; > + mfn = (ptep->pte & PTE_PFN_MASK) >> PAGE_SHIFT; > + page = m2p_find_override(mfn); > + if (page != NULL && (page->private & GRANT_FRAME_BIT)) { > + int ret; > + struct gnttab_unmap_grant_ref kunmap_op; > + struct gnttab_map_grant_ref *kmap_op > + (struct gnttab_map_grant_ref *) page->index; > + kunmap_op.host_addr = kmap_op->host_addr; > + kunmap_op.handle = kmap_op->handle; > + kunmap_op.dev_bus_addr = 0; > + ret = HYPERVISOR_grant_table_op( > + GNTTABOP_unmap_grant_ref, &kunmap_op, 1); > + WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, failed to " > + "modify kernel mappings", page_to_pfn(page), mfn); > + return ret; > + } > + return 1; > +} > +#endif > + > static void xen_set_pte(pte_t *ptep, pte_t pteval) > { > +#ifdef CONFIG_HIGHMEM > + if (!(pte_flags(pteval) & _PAGE_USER)) { > + int ret; > + struct page *page; > + unsigned long mfn = (pteval.pte & PTE_PFN_MASK) >> PAGE_SHIFT; > + page = m2p_find_override(mfn); > + /* > + * if this is a granted page we need to use a grant table > + * hypercall to map it instead > + */ > + if (page != NULL && (page->private & GRANT_FRAME_BIT)) { > + struct gnttab_map_grant_ref *kmap_op > + (struct gnttab_map_grant_ref *) page->index; > + unsigned long old_mfn = kmap_op->dev_bus_addr; > + kmap_op->host_addr > + arbitrary_virt_to_machine(ptep).maddr; > + kmap_op->dev_bus_addr = 0; > + ret = HYPERVISOR_grant_table_op( > + GNTTABOP_map_grant_ref, kmap_op, 1); > + WARN(ret, "xen_set_pte: pfn %lx mfn %lx, failed to " > + "modify kernel mappings", > + page_to_pfn(page), mfn); > + kmap_op->dev_bus_addr = old_mfn; > + return; > + } > + /* > + * even if it is not a granted page, the old page we are about > + * to overwrite could be a granted page and in that case we need > + * to unmap it using a grant table hypercall > + */ > + xen_unmap_granted_page(ptep); > + } > +#endif > + > if (!xen_batched_set_pte(ptep, pteval)) > native_set_pte(ptep, pteval); > } > @@ -548,6 +610,12 @@ static void xen_set_pte_atomic(pte_t *ptep, pte_t pte) > > static void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) > { > + /* > + * check if this is a granted page and unmap it using a grant table > + * hypercall in that case > + */ > + if (!xen_unmap_granted_page(ptep)) > + return; > if (!xen_batched_set_pte(ptep, native_make_pte(0))) > native_pte_clear(mm, addr, ptep); > } > diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c > index 58efeb9..1c4d2b5 100644 > --- a/arch/x86/xen/p2m.c > +++ b/arch/x86/xen/p2m.c > @@ -161,6 +161,7 @@ > #include <asm/xen/page.h> > #include <asm/xen/hypercall.h> > #include <asm/xen/hypervisor.h> > +#include <xen/grant_table.h> > > #include "xen-ops.h" > > @@ -676,7 +677,8 @@ static unsigned long mfn_hash(unsigned long mfn) > } > > /* Add an MFN override for a particular page */ > -int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte) > +int m2p_add_override(unsigned long mfn, struct page *page, > + struct gnttab_map_grant_ref *kmap_op) > { > unsigned long flags; > unsigned long pfn; > @@ -699,9 +701,18 @@ int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte) > if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) > return -ENOMEM; > > - if (clear_pte && !PageHighMem(page)) > - /* Just zap old mapping for now */ > - pte_clear(&init_mm, address, ptep); > + if (kmap_op != NULL) { > + if (!PageHighMem(page)) { > + int ret = HYPERVISOR_grant_table_op( > + GNTTABOP_map_grant_ref, kmap_op, 1); > + WARN(ret, "m2p_add_override: pfn %lx mfn %lx, " > + "failed to modify kernel mappings", pfn, mfn); > + } > + page->private |= GRANT_FRAME_BIT; > + /* let''s use dev_bus_addr to record the old mfn instead */ > + kmap_op->dev_bus_addr = page->index; > + page->index = (unsigned long) kmap_op; > + } > spin_lock_irqsave(&m2p_override_lock, flags); > list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); > spin_unlock_irqrestore(&m2p_override_lock, flags); > @@ -735,13 +746,27 @@ int m2p_remove_override(struct page *page, bool clear_pte) > spin_lock_irqsave(&m2p_override_lock, flags); > list_del(&page->lru); > spin_unlock_irqrestore(&m2p_override_lock, flags); > - set_phys_to_machine(pfn, page->index); > > - if (clear_pte && !PageHighMem(page)) > - set_pte_at(&init_mm, address, ptep, > - pfn_pte(pfn, PAGE_KERNEL)); > - /* No tlb flush necessary because the caller already > - * left the pte unmapped. */ > + if (clear_pte) { > + struct gnttab_map_grant_ref *map_op > + (struct gnttab_map_grant_ref *) page->index; > + set_phys_to_machine(pfn, map_op->dev_bus_addr); > + if (!PageHighMem(page)) { > + int ret; > + struct gnttab_unmap_grant_ref unmap_op; > + unmap_op.host_addr = map_op->host_addr; > + unmap_op.handle = map_op->handle; > + unmap_op.dev_bus_addr = 0; > + ret = HYPERVISOR_grant_table_op( > + GNTTABOP_unmap_grant_ref, &unmap_op, 1); > + WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, " > + "failed to modify kernel mappings", pfn, mfn); > + set_pte_at(&init_mm, address, ptep, > + pfn_pte(pfn, PAGE_KERNEL)); > + __flush_tlb_single(address); > + } > + } else > + set_phys_to_machine(pfn, page->index); > > return 0; > } > @@ -758,7 +783,7 @@ struct page *m2p_find_override(unsigned long mfn) > spin_lock_irqsave(&m2p_override_lock, flags); > > list_for_each_entry(p, bucket, lru) { > - if (p->private == mfn) { > + if ((p->private & (~GRANT_FRAME_BIT)) == mfn) { > ret = p; > break; > } > diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c > index f914b26..ca41772 100644 > --- a/drivers/xen/gntdev.c > +++ b/drivers/xen/gntdev.c > @@ -83,6 +83,7 @@ struct grant_map { > struct ioctl_gntdev_grant_ref *grants; > struct gnttab_map_grant_ref *map_ops; > struct gnttab_unmap_grant_ref *unmap_ops; > + struct gnttab_map_grant_ref *kmap_ops; > struct page **pages; > }; > > @@ -116,10 +117,12 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) > add->grants = kzalloc(sizeof(add->grants[0]) * count, GFP_KERNEL); > add->map_ops = kzalloc(sizeof(add->map_ops[0]) * count, GFP_KERNEL); > add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL); > + add->kmap_ops = kzalloc(sizeof(add->kmap_ops[0]) * count, GFP_KERNEL); > add->pages = kzalloc(sizeof(add->pages[0]) * count, GFP_KERNEL); > if (NULL == add->grants || > NULL == add->map_ops || > NULL == add->unmap_ops || > + NULL == add->kmap_ops || > NULL == add->pages) > goto err; > > @@ -129,6 +132,7 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) > for (i = 0; i < count; i++) { > add->map_ops[i].handle = -1; > add->unmap_ops[i].handle = -1; > + add->kmap_ops[i].handle = -1; > } > > add->index = 0; > @@ -142,6 +146,7 @@ err: > kfree(add->grants); > kfree(add->map_ops); > kfree(add->unmap_ops); > + kfree(add->kmap_ops); > kfree(add); > return NULL; > } > @@ -243,10 +248,30 @@ static int map_grant_pages(struct grant_map *map) > gnttab_set_unmap_op(&map->unmap_ops[i], addr, > map->flags, -1 /* handle */); > } > + } else { > + for (i = 0; i < map->count; i++) { > + unsigned level; > + unsigned long address = (unsigned long) > + pfn_to_kaddr(page_to_pfn(map->pages[i])); > + pte_t *ptep; > + u64 pte_maddr = 0; > + if (!PageHighMem(map->pages[i])) { > + ptep = lookup_address(address, &level); > + pte_maddr > + arbitrary_virt_to_machine(ptep).maddr; > + } > + gnttab_set_map_op(&map->kmap_ops[i], pte_maddr, > + map->flags | > + GNTMAP_host_map | > + GNTMAP_contains_pte, > + map->grants[i].ref, > + map->grants[i].domid); > + } > } > > pr_debug("map %d+%d\n", map->index, map->count); > - err = gnttab_map_refs(map->map_ops, map->pages, map->count); > + err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, > + map->pages, map->count); > if (err) > return err; > > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > index fd725cd..1e8669a 100644 > --- a/drivers/xen/grant-table.c > +++ b/drivers/xen/grant-table.c > @@ -448,6 +448,7 @@ unsigned int gnttab_max_grant_frames(void) > EXPORT_SYMBOL_GPL(gnttab_max_grant_frames); > > int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > + struct gnttab_map_grant_ref *kmap_ops, > struct page **pages, unsigned int count) > { > int i, ret; > @@ -488,8 +489,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > */ > return -EOPNOTSUPP; > } > - ret = m2p_add_override(mfn, pages[i], > - map_ops[i].flags & GNTMAP_contains_pte); > + ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]); > if (ret) > return ret; > } > diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h > index b1fab6b..6b99bfb 100644 > --- a/include/xen/grant_table.h > +++ b/include/xen/grant_table.h > @@ -156,6 +156,7 @@ unsigned int gnttab_max_grant_frames(void); > #define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr)) > > int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > + struct gnttab_map_grant_ref *kmap_ops, > struct page **pages, unsigned int count); > int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, > struct page **pages, unsigned int count);_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Ian Campbell
2011-Aug-09 12:30 UTC
[Xen-devel] Re: [PATCH] xen: modify kernel mappings corresponding to granted pages
On Tue, 2011-08-09 at 03:34 +0100, Konrad Rzeszutek Wilk wrote:> On Tue, Jul 26, 2011 at 05:55:45PM +0100, stefano.stabellini@eu.citrix.com wrote: > > From: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > > > If we want to use granted pages for AIO, changing the mappings of a user > > vma and the corresponding p2m is not enough, we also need to update the > > kernel mappings accordingly. > > On x86_64 it is easy, we can issue another HYPERVISOR_grant_table_op > > right away in m2p_add_override. We can remove the mappings using another > > HYPERVISOR_grant_table_op in m2p_remove_override. > > On x86_32 it is more difficult because the pages are highmem pages and > > therefore we need to catch the set_pte that tries to map a granted page > > and issue an HYPERVISOR_grant_table_op instead. > > Same thing for unmapping them: we need to catch the pte clear or the > > set_pte that try to unmap a granted page and issue an > > HYPERVISOR_grant_table_op. > > So I hadn''t looked at this in detail, but I wonder if we can use the > MULTIcall for this? It looks like we need to do two hypercalls so why > not batch it?That was going to be my next question. We should definitely batch these if possible.> And while we are it - we could change the MMU ops to only do this on > initial domain and for the domU case do the old mechanism?We need this in domU for driver domains and the like, don''t we?> In essence > adding two variants of the xen_set_pte - domU and dom0? .. And we > should get rid of the debug one (xen_set_pte_debug) - it has helped a bit > but I don''t think anybody is using it except me. > > > > > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > --- > > arch/x86/include/asm/xen/page.h | 5 ++- > > arch/x86/xen/mmu.c | 68 +++++++++++++++++++++++++++++++++++++++ > > arch/x86/xen/p2m.c | 47 ++++++++++++++++++++------ > > drivers/xen/gntdev.c | 27 +++++++++++++++- > > drivers/xen/grant-table.c | 4 +- > > include/xen/grant_table.h | 1 + > > 6 files changed, 137 insertions(+), 15 deletions(-) > > > > diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h > > index 64a619d..ec7bbfb 100644 > > --- a/arch/x86/include/asm/xen/page.h > > +++ b/arch/x86/include/asm/xen/page.h > > @@ -12,6 +12,7 @@ > > #include <asm/pgtable.h> > > > > #include <xen/interface/xen.h> > > +#include <xen/grant_table.h> > > #include <xen/features.h> > > > > /* Xen machine address */ > > @@ -31,8 +32,10 @@ typedef struct xpaddr { > > #define INVALID_P2M_ENTRY (~0UL) > > #define FOREIGN_FRAME_BIT (1UL<<(BITS_PER_LONG-1)) > > #define IDENTITY_FRAME_BIT (1UL<<(BITS_PER_LONG-2)) > > +#define GRANT_FRAME_BIT (1UL<<(BITS_PER_LONG-3)) > > #define FOREIGN_FRAME(m) ((m) | FOREIGN_FRAME_BIT) > > #define IDENTITY_FRAME(m) ((m) | IDENTITY_FRAME_BIT) > > +#define GRANT_FRAME(m) ((m) | GRANT_FRAME_BIT) > > > > /* Maximum amount of memory we can handle in a domain in pages */ > > #define MAX_DOMAIN_PAGES \ > > @@ -48,7 +51,7 @@ extern unsigned long set_phys_range_identity(unsigned long pfn_s, > > unsigned long pfn_e); > > > > extern int m2p_add_override(unsigned long mfn, struct page *page, > > - bool clear_pte); > > + struct gnttab_map_grant_ref *kmap_op); > > extern int m2p_remove_override(struct page *page, bool clear_pte); > > extern struct page *m2p_find_override(unsigned long mfn); > > extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn); > > diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c > > index 4e37a7c0..13f20d8 100644 > > --- a/arch/x86/xen/mmu.c > > +++ b/arch/x86/xen/mmu.c > > @@ -282,8 +282,70 @@ static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval) > > return true; > > } > > > > +#ifdef CONFIG_HIGHMEM > > +static int xen_unmap_granted_page(pte_t *ptep) > > +{ > > + unsigned long mfn; > > + struct page *page; > > + > > + if (pte_flags(*ptep) & _PAGE_USER) > > + return 1; > > + mfn = (ptep->pte & PTE_PFN_MASK) >> PAGE_SHIFT; > > + page = m2p_find_override(mfn); > > + if (page != NULL && (page->private & GRANT_FRAME_BIT)) { > > + int ret; > > + struct gnttab_unmap_grant_ref kunmap_op; > > + struct gnttab_map_grant_ref *kmap_op > > + (struct gnttab_map_grant_ref *) page->index; > > + kunmap_op.host_addr = kmap_op->host_addr; > > + kunmap_op.handle = kmap_op->handle; > > + kunmap_op.dev_bus_addr = 0; > > + ret = HYPERVISOR_grant_table_op( > > + GNTTABOP_unmap_grant_ref, &kunmap_op, 1); > > + WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, failed to " > > + "modify kernel mappings", page_to_pfn(page), mfn); > > + return ret; > > + } > > + return 1; > > +} > > +#endif > > + > > static void xen_set_pte(pte_t *ptep, pte_t pteval) > > { > > +#ifdef CONFIG_HIGHMEM > > + if (!(pte_flags(pteval) & _PAGE_USER)) { > > + int ret; > > + struct page *page; > > + unsigned long mfn = (pteval.pte & PTE_PFN_MASK) >> PAGE_SHIFT; > > + page = m2p_find_override(mfn); > > + /* > > + * if this is a granted page we need to use a grant table > > + * hypercall to map it instead > > + */ > > + if (page != NULL && (page->private & GRANT_FRAME_BIT)) { > > + struct gnttab_map_grant_ref *kmap_op > > + (struct gnttab_map_grant_ref *) page->index; > > + unsigned long old_mfn = kmap_op->dev_bus_addr; > > + kmap_op->host_addr > > + arbitrary_virt_to_machine(ptep).maddr; > > + kmap_op->dev_bus_addr = 0; > > + ret = HYPERVISOR_grant_table_op( > > + GNTTABOP_map_grant_ref, kmap_op, 1); > > + WARN(ret, "xen_set_pte: pfn %lx mfn %lx, failed to " > > + "modify kernel mappings", > > + page_to_pfn(page), mfn); > > + kmap_op->dev_bus_addr = old_mfn; > > + return; > > + } > > + /* > > + * even if it is not a granted page, the old page we are about > > + * to overwrite could be a granted page and in that case we need > > + * to unmap it using a grant table hypercall > > + */ > > + xen_unmap_granted_page(ptep); > > + } > > +#endif > > + > > if (!xen_batched_set_pte(ptep, pteval)) > > native_set_pte(ptep, pteval); > > } > > @@ -548,6 +610,12 @@ static void xen_set_pte_atomic(pte_t *ptep, pte_t pte) > > > > static void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) > > { > > + /* > > + * check if this is a granted page and unmap it using a grant table > > + * hypercall in that case > > + */ > > + if (!xen_unmap_granted_page(ptep)) > > + return; > > if (!xen_batched_set_pte(ptep, native_make_pte(0))) > > native_pte_clear(mm, addr, ptep); > > } > > diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c > > index 58efeb9..1c4d2b5 100644 > > --- a/arch/x86/xen/p2m.c > > +++ b/arch/x86/xen/p2m.c > > @@ -161,6 +161,7 @@ > > #include <asm/xen/page.h> > > #include <asm/xen/hypercall.h> > > #include <asm/xen/hypervisor.h> > > +#include <xen/grant_table.h> > > > > #include "xen-ops.h" > > > > @@ -676,7 +677,8 @@ static unsigned long mfn_hash(unsigned long mfn) > > } > > > > /* Add an MFN override for a particular page */ > > -int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte) > > +int m2p_add_override(unsigned long mfn, struct page *page, > > + struct gnttab_map_grant_ref *kmap_op) > > { > > unsigned long flags; > > unsigned long pfn; > > @@ -699,9 +701,18 @@ int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte) > > if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) > > return -ENOMEM; > > > > - if (clear_pte && !PageHighMem(page)) > > - /* Just zap old mapping for now */ > > - pte_clear(&init_mm, address, ptep); > > + if (kmap_op != NULL) { > > + if (!PageHighMem(page)) { > > + int ret = HYPERVISOR_grant_table_op( > > + GNTTABOP_map_grant_ref, kmap_op, 1); > > + WARN(ret, "m2p_add_override: pfn %lx mfn %lx, " > > + "failed to modify kernel mappings", pfn, mfn); > > + } > > + page->private |= GRANT_FRAME_BIT; > > + /* let''s use dev_bus_addr to record the old mfn instead */ > > + kmap_op->dev_bus_addr = page->index; > > + page->index = (unsigned long) kmap_op; > > + } > > spin_lock_irqsave(&m2p_override_lock, flags); > > list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); > > spin_unlock_irqrestore(&m2p_override_lock, flags); > > @@ -735,13 +746,27 @@ int m2p_remove_override(struct page *page, bool clear_pte) > > spin_lock_irqsave(&m2p_override_lock, flags); > > list_del(&page->lru); > > spin_unlock_irqrestore(&m2p_override_lock, flags); > > - set_phys_to_machine(pfn, page->index); > > > > - if (clear_pte && !PageHighMem(page)) > > - set_pte_at(&init_mm, address, ptep, > > - pfn_pte(pfn, PAGE_KERNEL)); > > - /* No tlb flush necessary because the caller already > > - * left the pte unmapped. */ > > + if (clear_pte) { > > + struct gnttab_map_grant_ref *map_op > > + (struct gnttab_map_grant_ref *) page->index; > > + set_phys_to_machine(pfn, map_op->dev_bus_addr); > > + if (!PageHighMem(page)) { > > + int ret; > > + struct gnttab_unmap_grant_ref unmap_op; > > + unmap_op.host_addr = map_op->host_addr; > > + unmap_op.handle = map_op->handle; > > + unmap_op.dev_bus_addr = 0; > > + ret = HYPERVISOR_grant_table_op( > > + GNTTABOP_unmap_grant_ref, &unmap_op, 1); > > + WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, " > > + "failed to modify kernel mappings", pfn, mfn); > > + set_pte_at(&init_mm, address, ptep, > > + pfn_pte(pfn, PAGE_KERNEL)); > > + __flush_tlb_single(address); > > + } > > + } else > > + set_phys_to_machine(pfn, page->index); > > > > return 0; > > } > > @@ -758,7 +783,7 @@ struct page *m2p_find_override(unsigned long mfn) > > spin_lock_irqsave(&m2p_override_lock, flags); > > > > list_for_each_entry(p, bucket, lru) { > > - if (p->private == mfn) { > > + if ((p->private & (~GRANT_FRAME_BIT)) == mfn) { > > ret = p; > > break; > > } > > diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c > > index f914b26..ca41772 100644 > > --- a/drivers/xen/gntdev.c > > +++ b/drivers/xen/gntdev.c > > @@ -83,6 +83,7 @@ struct grant_map { > > struct ioctl_gntdev_grant_ref *grants; > > struct gnttab_map_grant_ref *map_ops; > > struct gnttab_unmap_grant_ref *unmap_ops; > > + struct gnttab_map_grant_ref *kmap_ops; > > struct page **pages; > > }; > > > > @@ -116,10 +117,12 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) > > add->grants = kzalloc(sizeof(add->grants[0]) * count, GFP_KERNEL); > > add->map_ops = kzalloc(sizeof(add->map_ops[0]) * count, GFP_KERNEL); > > add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL); > > + add->kmap_ops = kzalloc(sizeof(add->kmap_ops[0]) * count, GFP_KERNEL); > > add->pages = kzalloc(sizeof(add->pages[0]) * count, GFP_KERNEL); > > if (NULL == add->grants || > > NULL == add->map_ops || > > NULL == add->unmap_ops || > > + NULL == add->kmap_ops || > > NULL == add->pages) > > goto err; > > > > @@ -129,6 +132,7 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) > > for (i = 0; i < count; i++) { > > add->map_ops[i].handle = -1; > > add->unmap_ops[i].handle = -1; > > + add->kmap_ops[i].handle = -1; > > } > > > > add->index = 0; > > @@ -142,6 +146,7 @@ err: > > kfree(add->grants); > > kfree(add->map_ops); > > kfree(add->unmap_ops); > > + kfree(add->kmap_ops); > > kfree(add); > > return NULL; > > } > > @@ -243,10 +248,30 @@ static int map_grant_pages(struct grant_map *map) > > gnttab_set_unmap_op(&map->unmap_ops[i], addr, > > map->flags, -1 /* handle */); > > } > > + } else { > > + for (i = 0; i < map->count; i++) { > > + unsigned level; > > + unsigned long address = (unsigned long) > > + pfn_to_kaddr(page_to_pfn(map->pages[i])); > > + pte_t *ptep; > > + u64 pte_maddr = 0; > > + if (!PageHighMem(map->pages[i])) { > > + ptep = lookup_address(address, &level); > > + pte_maddr > > + arbitrary_virt_to_machine(ptep).maddr; > > + } > > + gnttab_set_map_op(&map->kmap_ops[i], pte_maddr, > > + map->flags | > > + GNTMAP_host_map | > > + GNTMAP_contains_pte, > > + map->grants[i].ref, > > + map->grants[i].domid); > > + } > > } > > > > pr_debug("map %d+%d\n", map->index, map->count); > > - err = gnttab_map_refs(map->map_ops, map->pages, map->count); > > + err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, > > + map->pages, map->count); > > if (err) > > return err; > > > > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > > index fd725cd..1e8669a 100644 > > --- a/drivers/xen/grant-table.c > > +++ b/drivers/xen/grant-table.c > > @@ -448,6 +448,7 @@ unsigned int gnttab_max_grant_frames(void) > > EXPORT_SYMBOL_GPL(gnttab_max_grant_frames); > > > > int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > > + struct gnttab_map_grant_ref *kmap_ops, > > struct page **pages, unsigned int count) > > { > > int i, ret; > > @@ -488,8 +489,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > > */ > > return -EOPNOTSUPP; > > } > > - ret = m2p_add_override(mfn, pages[i], > > - map_ops[i].flags & GNTMAP_contains_pte); > > + ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]); > > if (ret) > > return ret; > > } > > diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h > > index b1fab6b..6b99bfb 100644 > > --- a/include/xen/grant_table.h > > +++ b/include/xen/grant_table.h > > @@ -156,6 +156,7 @@ unsigned int gnttab_max_grant_frames(void); > > #define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr)) > > > > int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > > + struct gnttab_map_grant_ref *kmap_ops, > > struct page **pages, unsigned int count); > > int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, > > struct page **pages, unsigned int count); > > -- > > 1.7.2.3_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Konrad Rzeszutek Wilk
2011-Aug-09 15:50 UTC
[Xen-devel] Re: [PATCH] xen: modify kernel mappings corresponding to granted pages
> > So I hadn''t looked at this in detail, but I wonder if we can use the > > MULTIcall for this? It looks like we need to do two hypercalls so why > > not batch it? > > That was going to be my next question. We should definitely batch these > if possible. > > > And while we are it - we could change the MMU ops to only do this on > > initial domain and for the domU case do the old mechanism? > > We need this in domU for driver domains and the like, don''t we?Sure, but I believe the majority of domU domains would not require this. I was thinking that when we start playing with the device/driver domains we would want to escalate the privilige level (or perhaps not)? Or perhaps introcuce a new type - "if (xen_driver_domain())" to recognize that we are special ? _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Ian Campbell
2011-Aug-10 08:06 UTC
[Xen-devel] Re: [PATCH] xen: modify kernel mappings corresponding to granted pages
On Tue, 2011-08-09 at 16:50 +0100, Konrad Rzeszutek Wilk wrote:> > > So I hadn''t looked at this in detail, but I wonder if we can use the > > > MULTIcall for this? It looks like we need to do two hypercalls so why > > > not batch it? > > > > That was going to be my next question. We should definitely batch these > > if possible. > > > > > And while we are it - we could change the MMU ops to only do this on > > > initial domain and for the domU case do the old mechanism? > > > > We need this in domU for driver domains and the like, don''t we? > > Sure, but I believe the majority of domU domains would not require this.The overhead of this stuff is low if not used, isn''t it? Compared with the complexity of having domains know if they might be used as a driver domain or not that seems like the tradeoff to be aiming for.> I was thinking that when we start playing with the device/driver domains > we would want to escalate the privilige level (or perhaps not)?We don''t want any escalation of privilege over and above what is necessary to be a driver domain, which is generally none.> Or > perhaps introcuce a new type - "if (xen_driver_domain())" to recognize > that we are special ?Where does the information to set xen_driver_domain == TRUE come from? Ian. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Ian Campbell
2011-Aug-10 08:23 UTC
[Xen-devel] Re: [PATCH] xen: modify kernel mappings corresponding to granted pages
On Tue, 2011-07-26 at 17:55 +0100, stefano.stabellini@eu.citrix.com wrote:> From: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > If we want to use granted pages for AIO, changing the mappings of a user > vma and the corresponding p2m is not enough, we also need to update the > kernel mappings accordingly. > On x86_64 it is easy, we can issue another HYPERVISOR_grant_table_op > right away in m2p_add_override. We can remove the mappings using another > HYPERVISOR_grant_table_op in m2p_remove_override. > On x86_32 it is more difficult because the pages are highmem pagesAren''t kernel mappings of highmem pages always in the fixmap? Therefore can we maybe catch this at that layer in the pvops infrastructure? That would avoid the impact on all set_pte calls and (perhaps) provide more context regarding the mapping. For example that might mean we could keep a bitmap (or other data structure as appropriate) mapping the fixmap IDX (which is a smallish integer, far more manageable than {P,M}FN) into granted-ness in order to speed up the check for this case. Avoiding the m2p_override lookup in the common case seems like something which would be worth putting some effort into.> and > therefore we need to catch the set_pte that tries to map a granted page > and issue an HYPERVISOR_grant_table_op instead.> Same thing for unmapping them: we need to catch the pte clear or the > set_pte that try to unmap a granted page and issue an > HYPERVISOR_grant_table_op. > > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > --- > arch/x86/include/asm/xen/page.h | 5 ++- > arch/x86/xen/mmu.c | 68 +++++++++++++++++++++++++++++++++++++++ > arch/x86/xen/p2m.c | 47 ++++++++++++++++++++------ > drivers/xen/gntdev.c | 27 +++++++++++++++- > drivers/xen/grant-table.c | 4 +- > include/xen/grant_table.h | 1 + > 6 files changed, 137 insertions(+), 15 deletions(-) > > diff --git a/arch/x86/include/asm/xen/page.h b/arch/x86/include/asm/xen/page.h > index 64a619d..ec7bbfb 100644 > --- a/arch/x86/include/asm/xen/page.h > +++ b/arch/x86/include/asm/xen/page.h > @@ -12,6 +12,7 @@ > #include <asm/pgtable.h> > > #include <xen/interface/xen.h> > +#include <xen/grant_table.h> > #include <xen/features.h> > > /* Xen machine address */ > @@ -31,8 +32,10 @@ typedef struct xpaddr { > #define INVALID_P2M_ENTRY (~0UL) > #define FOREIGN_FRAME_BIT (1UL<<(BITS_PER_LONG-1)) > #define IDENTITY_FRAME_BIT (1UL<<(BITS_PER_LONG-2)) > +#define GRANT_FRAME_BIT (1UL<<(BITS_PER_LONG-3)) > #define FOREIGN_FRAME(m) ((m) | FOREIGN_FRAME_BIT) > #define IDENTITY_FRAME(m) ((m) | IDENTITY_FRAME_BIT) > +#define GRANT_FRAME(m) ((m) | GRANT_FRAME_BIT)GRANT_FRAME_BIT, despite being declared like {FOREIGN,IDENTITY}_FRAME_BIT is not actually used in the upper bits of an MFN but rather is used as a flag in page->private. If it''s not to be used in an MFN in the style of the others then there is no need for it to follow that pattern. The declaration of GRANT_FRAME is unused and confusing since the bit isn''t even used that way. If page->private is to be used as a bitfield then it needs to be clear which bits are used in that context vs. the MFN high bits, i.e. it should be declared somewhere else with an appropriate comment. More importantly though are we sure that page->private is always available for use by this code? The private field is for the use of the owner of the page. In the case where the page is a granted page then we are (ultimately) the owner, but in the case where the page isn''t a granted page at all the owner could be another subsystem altogether and there could be false positives if that bit happens to be set.> > /* Maximum amount of memory we can handle in a domain in pages */ > #define MAX_DOMAIN_PAGES \ > @@ -48,7 +51,7 @@ extern unsigned long set_phys_range_identity(unsigned long pfn_s, > unsigned long pfn_e); > > extern int m2p_add_override(unsigned long mfn, struct page *page, > - bool clear_pte); > + struct gnttab_map_grant_ref *kmap_op); > extern int m2p_remove_override(struct page *page, bool clear_pte); > extern struct page *m2p_find_override(unsigned long mfn); > extern unsigned long m2p_find_override_pfn(unsigned long mfn, unsigned long pfn); > diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c > index 4e37a7c0..13f20d8 100644 > --- a/arch/x86/xen/mmu.c > +++ b/arch/x86/xen/mmu.c > @@ -282,8 +282,70 @@ static bool xen_batched_set_pte(pte_t *ptep, pte_t pteval) > return true; > } > > +#ifdef CONFIG_HIGHMEM > +static int xen_unmap_granted_page(pte_t *ptep) > +{ > + unsigned long mfn; > + struct page *page; > + > + if (pte_flags(*ptep) & _PAGE_USER) > + return 1; > + mfn = (ptep->pte & PTE_PFN_MASK) >> PAGE_SHIFT; > + page = m2p_find_override(mfn); > + if (page != NULL && (page->private & GRANT_FRAME_BIT)) { > + int ret; > + struct gnttab_unmap_grant_ref kunmap_op; > + struct gnttab_map_grant_ref *kmap_op > + (struct gnttab_map_grant_ref *) page->index; > + kunmap_op.host_addr = kmap_op->host_addr; > + kunmap_op.handle = kmap_op->handle; > + kunmap_op.dev_bus_addr = 0; > + ret = HYPERVISOR_grant_table_op( > + GNTTABOP_unmap_grant_ref, &kunmap_op, 1); > + WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, failed to " > + "modify kernel mappings", page_to_pfn(page), mfn); > + return ret; > + } > + return 1; > +} > +#endif > + > static void xen_set_pte(pte_t *ptep, pte_t pteval) > { > +#ifdef CONFIG_HIGHMEM > + if (!(pte_flags(pteval) & _PAGE_USER)) { > + int ret; > + struct page *page; > + unsigned long mfn = (pteval.pte & PTE_PFN_MASK) >> PAGE_SHIFT; > + page = m2p_find_override(mfn); > + /* > + * if this is a granted page we need to use a grant table > + * hypercall to map it instead > + */ > + if (page != NULL && (page->private & GRANT_FRAME_BIT)) { > + struct gnttab_map_grant_ref *kmap_op > + (struct gnttab_map_grant_ref *) page->index; > + unsigned long old_mfn = kmap_op->dev_bus_addr; > + kmap_op->host_addr > + arbitrary_virt_to_machine(ptep).maddr; > + kmap_op->dev_bus_addr = 0; > + ret = HYPERVISOR_grant_table_op( > + GNTTABOP_map_grant_ref, kmap_op, 1); > + WARN(ret, "xen_set_pte: pfn %lx mfn %lx, failed to " > + "modify kernel mappings", > + page_to_pfn(page), mfn); > + kmap_op->dev_bus_addr = old_mfn; > + return; > + } > + /* > + * even if it is not a granted page, the old page we are about > + * to overwrite could be a granted page and in that case we need > + * to unmap it using a grant table hypercall > + */ > + xen_unmap_granted_page(ptep); > + } > +#endif > + > if (!xen_batched_set_pte(ptep, pteval)) > native_set_pte(ptep, pteval); > } > @@ -548,6 +610,12 @@ static void xen_set_pte_atomic(pte_t *ptep, pte_t pte) > > static void xen_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) > { > + /* > + * check if this is a granted page and unmap it using a grant table > + * hypercall in that case > + */ > + if (!xen_unmap_granted_page(ptep)) > + return; > if (!xen_batched_set_pte(ptep, native_make_pte(0))) > native_pte_clear(mm, addr, ptep); > } > diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c > index 58efeb9..1c4d2b5 100644 > --- a/arch/x86/xen/p2m.c > +++ b/arch/x86/xen/p2m.c > @@ -161,6 +161,7 @@ > #include <asm/xen/page.h> > #include <asm/xen/hypercall.h> > #include <asm/xen/hypervisor.h> > +#include <xen/grant_table.h> > > #include "xen-ops.h" > > @@ -676,7 +677,8 @@ static unsigned long mfn_hash(unsigned long mfn) > } > > /* Add an MFN override for a particular page */ > -int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte) > +int m2p_add_override(unsigned long mfn, struct page *page, > + struct gnttab_map_grant_ref *kmap_op) > { > unsigned long flags; > unsigned long pfn; > @@ -699,9 +701,18 @@ int m2p_add_override(unsigned long mfn, struct page *page, bool clear_pte) > if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) > return -ENOMEM; > > - if (clear_pte && !PageHighMem(page)) > - /* Just zap old mapping for now */ > - pte_clear(&init_mm, address, ptep); > + if (kmap_op != NULL) { > + if (!PageHighMem(page)) { > + int ret = HYPERVISOR_grant_table_op( > + GNTTABOP_map_grant_ref, kmap_op, 1); > + WARN(ret, "m2p_add_override: pfn %lx mfn %lx, " > + "failed to modify kernel mappings", pfn, mfn); > + } > + page->private |= GRANT_FRAME_BIT; > + /* let''s use dev_bus_addr to record the old mfn instead */ > + kmap_op->dev_bus_addr = page->index; > + page->index = (unsigned long) kmap_op; > + } > spin_lock_irqsave(&m2p_override_lock, flags); > list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); > spin_unlock_irqrestore(&m2p_override_lock, flags); > @@ -735,13 +746,27 @@ int m2p_remove_override(struct page *page, bool clear_pte) > spin_lock_irqsave(&m2p_override_lock, flags); > list_del(&page->lru); > spin_unlock_irqrestore(&m2p_override_lock, flags); > - set_phys_to_machine(pfn, page->index); > > - if (clear_pte && !PageHighMem(page)) > - set_pte_at(&init_mm, address, ptep, > - pfn_pte(pfn, PAGE_KERNEL)); > - /* No tlb flush necessary because the caller already > - * left the pte unmapped. */ > + if (clear_pte) { > + struct gnttab_map_grant_ref *map_op > + (struct gnttab_map_grant_ref *) page->index; > + set_phys_to_machine(pfn, map_op->dev_bus_addr); > + if (!PageHighMem(page)) { > + int ret; > + struct gnttab_unmap_grant_ref unmap_op; > + unmap_op.host_addr = map_op->host_addr; > + unmap_op.handle = map_op->handle; > + unmap_op.dev_bus_addr = 0; > + ret = HYPERVISOR_grant_table_op( > + GNTTABOP_unmap_grant_ref, &unmap_op, 1); > + WARN(ret, "m2p_remove_override: pfn %lx mfn %lx, " > + "failed to modify kernel mappings", pfn, mfn); > + set_pte_at(&init_mm, address, ptep, > + pfn_pte(pfn, PAGE_KERNEL)); > + __flush_tlb_single(address); > + } > + } else > + set_phys_to_machine(pfn, page->index); > > return 0; > } > @@ -758,7 +783,7 @@ struct page *m2p_find_override(unsigned long mfn) > spin_lock_irqsave(&m2p_override_lock, flags); > > list_for_each_entry(p, bucket, lru) { > - if (p->private == mfn) { > + if ((p->private & (~GRANT_FRAME_BIT)) == mfn) { > ret = p; > break; > } > diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c > index f914b26..ca41772 100644 > --- a/drivers/xen/gntdev.c > +++ b/drivers/xen/gntdev.c > @@ -83,6 +83,7 @@ struct grant_map { > struct ioctl_gntdev_grant_ref *grants; > struct gnttab_map_grant_ref *map_ops; > struct gnttab_unmap_grant_ref *unmap_ops; > + struct gnttab_map_grant_ref *kmap_ops; > struct page **pages; > }; > > @@ -116,10 +117,12 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) > add->grants = kzalloc(sizeof(add->grants[0]) * count, GFP_KERNEL); > add->map_ops = kzalloc(sizeof(add->map_ops[0]) * count, GFP_KERNEL); > add->unmap_ops = kzalloc(sizeof(add->unmap_ops[0]) * count, GFP_KERNEL); > + add->kmap_ops = kzalloc(sizeof(add->kmap_ops[0]) * count, GFP_KERNEL); > add->pages = kzalloc(sizeof(add->pages[0]) * count, GFP_KERNEL); > if (NULL == add->grants || > NULL == add->map_ops || > NULL == add->unmap_ops || > + NULL == add->kmap_ops || > NULL == add->pages) > goto err; > > @@ -129,6 +132,7 @@ static struct grant_map *gntdev_alloc_map(struct gntdev_priv *priv, int count) > for (i = 0; i < count; i++) { > add->map_ops[i].handle = -1; > add->unmap_ops[i].handle = -1; > + add->kmap_ops[i].handle = -1; > } > > add->index = 0; > @@ -142,6 +146,7 @@ err: > kfree(add->grants); > kfree(add->map_ops); > kfree(add->unmap_ops); > + kfree(add->kmap_ops); > kfree(add); > return NULL; > } > @@ -243,10 +248,30 @@ static int map_grant_pages(struct grant_map *map) > gnttab_set_unmap_op(&map->unmap_ops[i], addr, > map->flags, -1 /* handle */); > } > + } else { > + for (i = 0; i < map->count; i++) { > + unsigned level; > + unsigned long address = (unsigned long) > + pfn_to_kaddr(page_to_pfn(map->pages[i])); > + pte_t *ptep; > + u64 pte_maddr = 0; > + if (!PageHighMem(map->pages[i])) { > + ptep = lookup_address(address, &level); > + pte_maddr > + arbitrary_virt_to_machine(ptep).maddr; > + } > + gnttab_set_map_op(&map->kmap_ops[i], pte_maddr, > + map->flags | > + GNTMAP_host_map | > + GNTMAP_contains_pte, > + map->grants[i].ref, > + map->grants[i].domid); > + } > } > > pr_debug("map %d+%d\n", map->index, map->count); > - err = gnttab_map_refs(map->map_ops, map->pages, map->count); > + err = gnttab_map_refs(map->map_ops, use_ptemod ? map->kmap_ops : NULL, > + map->pages, map->count); > if (err) > return err; > > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > index fd725cd..1e8669a 100644 > --- a/drivers/xen/grant-table.c > +++ b/drivers/xen/grant-table.c > @@ -448,6 +448,7 @@ unsigned int gnttab_max_grant_frames(void) > EXPORT_SYMBOL_GPL(gnttab_max_grant_frames); > > int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > + struct gnttab_map_grant_ref *kmap_ops, > struct page **pages, unsigned int count) > { > int i, ret; > @@ -488,8 +489,7 @@ int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > */ > return -EOPNOTSUPP; > } > - ret = m2p_add_override(mfn, pages[i], > - map_ops[i].flags & GNTMAP_contains_pte); > + ret = m2p_add_override(mfn, pages[i], &kmap_ops[i]); > if (ret) > return ret; > } > diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h > index b1fab6b..6b99bfb 100644 > --- a/include/xen/grant_table.h > +++ b/include/xen/grant_table.h > @@ -156,6 +156,7 @@ unsigned int gnttab_max_grant_frames(void); > #define gnttab_map_vaddr(map) ((void *)(map.host_virt_addr)) > > int gnttab_map_refs(struct gnttab_map_grant_ref *map_ops, > + struct gnttab_map_grant_ref *kmap_ops, > struct page **pages, unsigned int count); > int gnttab_unmap_refs(struct gnttab_unmap_grant_ref *unmap_ops, > struct page **pages, unsigned int count);_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Konrad Rzeszutek Wilk
2011-Aug-10 13:50 UTC
Re: [Xen-devel] Re: [PATCH] xen: modify kernel mappings corresponding to granted pages
On Wed, Aug 10, 2011 at 09:06:04AM +0100, Ian Campbell wrote:> On Tue, 2011-08-09 at 16:50 +0100, Konrad Rzeszutek Wilk wrote: > > > > So I hadn''t looked at this in detail, but I wonder if we can use the > > > > MULTIcall for this? It looks like we need to do two hypercalls so why > > > > not batch it? > > > > > > That was going to be my next question. We should definitely batch these > > > if possible. > > > > > > > And while we are it - we could change the MMU ops to only do this on > > > > initial domain and for the domU case do the old mechanism? > > > > > > We need this in domU for driver domains and the like, don''t we? > > > > Sure, but I believe the majority of domU domains would not require this. > > The overhead of this stuff is low if not used, isn''t it? Compared with > the complexity of having domains know if they might be used as a driver > domain or not that seems like the tradeoff to be aiming for. > > > I was thinking that when we start playing with the device/driver domains > > we would want to escalate the privilige level (or perhaps not)? > > We don''t want any escalation of privilege over and above what is > necessary to be a driver domain, which is generally none. > > > Or > > perhaps introcuce a new type - "if (xen_driver_domain())" to recognize > > that we are special ? > > Where does the information to set xen_driver_domain == TRUE come from?No idea. Was just thinking about it.. but you have convienced me it is not worth looking at. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel
Stefano Stabellini
2011-Sep-06 16:19 UTC
[Xen-devel] Re: [PATCH] xen: modify kernel mappings corresponding to granted pages
On Tue, 9 Aug 2011, Konrad Rzeszutek Wilk wrote:> On Tue, Jul 26, 2011 at 05:55:45PM +0100, stefano.stabellini@eu.citrix.com wrote: > > From: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > > > If we want to use granted pages for AIO, changing the mappings of a user > > vma and the corresponding p2m is not enough, we also need to update the > > kernel mappings accordingly. > > On x86_64 it is easy, we can issue another HYPERVISOR_grant_table_op > > right away in m2p_add_override. We can remove the mappings using another > > HYPERVISOR_grant_table_op in m2p_remove_override. > > On x86_32 it is more difficult because the pages are highmem pages and > > therefore we need to catch the set_pte that tries to map a granted page > > and issue an HYPERVISOR_grant_table_op instead. > > Same thing for unmapping them: we need to catch the pte clear or the > > set_pte that try to unmap a granted page and issue an > > HYPERVISOR_grant_table_op. > > So I hadn''t looked at this in detail, but I wonder if we can use the > MULTIcall for this? It looks like we need to do two hypercalls so why > not batch it?It wasn''t easy but I managed to use multicalls in both m2p override and the highmem counterparts in xen/mmu.c. I''ll send the multicall changes as a separate patch because I think is going to be easier to read. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel