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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen-unstable] x86 shadow: explicitly link the pages of multipage shadows
# HG changeset patch
# User Tim Deegan <Tim.Deegan@xxxxxxxxxx>
# Date 1283336628 -3600
# Node ID 89d04df0a39153bfe0522e1c3c5c0ac0458b8a9b
# Parent 14fcf5b873445880a1c7ab2a63ac83b5351d6d80
x86 shadow: explicitly link the pages of multipage shadows
together using their list headers. Update the users of the
pinned-shadows list to expect l2_32 shadows to have four entries
in the list, which must be kept together during updates.
Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
---
xen/arch/x86/mm/shadow/common.c | 18 ++--
xen/arch/x86/mm/shadow/multi.c | 23 ++---
xen/arch/x86/mm/shadow/private.h | 167 ++++++++++++++++++++++++++++++---------
xen/include/asm-x86/mm.h | 15 ++-
4 files changed, 163 insertions(+), 60 deletions(-)
diff -r 14fcf5b87344 -r 89d04df0a391 xen/arch/x86/mm/shadow/common.c
--- a/xen/arch/x86/mm/shadow/common.c Wed Sep 01 11:23:47 2010 +0100
+++ b/xen/arch/x86/mm/shadow/common.c Wed Sep 01 11:23:48 2010 +0100
@@ -1377,7 +1377,7 @@ static void _shadow_prealloc(
/* Stage one: walk the list of pinned pages, unpinning them */
perfc_incr(shadow_prealloc_1);
- page_list_for_each_safe_reverse(sp, t,
&d->arch.paging.shadow.pinned_shadows)
+ foreach_pinned_shadow(d, sp, t)
{
smfn = page_to_mfn(sp);
@@ -1445,7 +1445,7 @@ static void shadow_blow_tables(struct do
ASSERT(v != NULL);
/* Pass one: unpin all pinned pages */
- page_list_for_each_safe_reverse(sp, t,
&d->arch.paging.shadow.pinned_shadows)
+ foreach_pinned_shadow(d, sp, t)
{
smfn = page_to_mfn(sp);
sh_unpin(v, smfn);
@@ -1527,6 +1527,7 @@ mfn_t shadow_alloc(struct domain *d,
{
struct page_info *sp = NULL;
unsigned int order = shadow_order(shadow_type);
+ struct page_list_head tmp_list;
cpumask_t mask;
void *p;
int i;
@@ -1571,6 +1572,11 @@ mfn_t shadow_alloc(struct domain *d,
backpointer = pfn_to_pdx(backpointer);
break;
}
+
+ /* Page lists don't have pointers back to the head structure, so
+ * it's safe to use a head structure on the stack to link the pages
+ * together. */
+ INIT_PAGE_LIST_HEAD(&tmp_list);
/* Init page info fields and clear the pages */
for ( i = 0; i < 1<<order ; i++ )
@@ -1598,6 +1604,7 @@ mfn_t shadow_alloc(struct domain *d,
&& i == 0 );
sp[i].v.sh.back = backpointer;
set_next_shadow(&sp[i], NULL);
+ page_list_add_tail(&sp[i], &tmp_list);
perfc_incr(shadow_alloc_count);
}
return page_to_mfn(sp);
@@ -2668,10 +2675,7 @@ static int sh_remove_shadow_via_pointer(
ASSERT(sp->u.sh.type > 0);
ASSERT(sp->u.sh.type < SH_type_max_shadow);
- ASSERT(sp->u.sh.type != SH_type_l2_32_shadow);
- ASSERT(sp->u.sh.type != SH_type_l2_pae_shadow);
- ASSERT(sp->u.sh.type != SH_type_l2h_pae_shadow);
- ASSERT(sp->u.sh.type != SH_type_l4_64_shadow);
+ ASSERT(sh_type_has_up_pointer(v, sp->u.sh.type));
if (sp->up == 0) return 0;
pmfn = _mfn(sp->up >> PAGE_SHIFT);
@@ -2823,7 +2827,7 @@ void sh_remove_shadows(struct vcpu *v, m
} \
if ( sh_type_is_pinnable(v, t) ) \
sh_unpin(v, smfn); \
- else \
+ else if ( sh_type_has_up_pointer(v, t) ) \
sh_remove_shadow_via_pointer(v, smfn); \
if( !fast \
&& (pg->count_info & PGC_page_table) \
diff -r 14fcf5b87344 -r 89d04df0a391 xen/arch/x86/mm/shadow/multi.c
--- a/xen/arch/x86/mm/shadow/multi.c Wed Sep 01 11:23:47 2010 +0100
+++ b/xen/arch/x86/mm/shadow/multi.c Wed Sep 01 11:23:48 2010 +0100
@@ -1588,10 +1588,7 @@ sh_make_shadow(struct vcpu *v, mfn_t gmf
SHADOW_DEBUG(MAKE_SHADOW, "(%05lx, %u)=>%05lx\n",
mfn_x(gmfn), shadow_type, mfn_x(smfn));
- if ( shadow_type != SH_type_l2_32_shadow
- && shadow_type != SH_type_l2_pae_shadow
- && shadow_type != SH_type_l2h_pae_shadow
- && shadow_type != SH_type_l4_64_shadow )
+ if ( sh_type_has_up_pointer(v, shadow_type) )
/* Lower-level shadow, not yet linked form a higher level */
mfn_to_page(smfn)->up = 0;
@@ -1622,7 +1619,10 @@ sh_make_shadow(struct vcpu *v, mfn_t gmf
page_list_for_each_safe(sp, t,
&v->domain->arch.paging.shadow.pinned_shadows)
{
if ( sp->u.sh.type == SH_type_l3_64_shadow )
+ {
sh_unpin(v, page_to_mfn(sp));
+ sp->up = 0;
+ }
}
v->domain->arch.paging.shadow.opt_flags &=
~SHOPT_LINUX_L3_TOPLEVEL;
}
@@ -2534,9 +2534,12 @@ int sh_safe_not_to_sync(struct vcpu *v,
struct page_info *sp;
mfn_t smfn;
+ if ( !sh_type_has_up_pointer(v, SH_type_l1_shadow) )
+ return 0;
+
smfn = get_shadow_status(v, gl1mfn, SH_type_l1_shadow);
ASSERT(mfn_valid(smfn)); /* Otherwise we would not have been called */
-
+
/* Up to l2 */
sp = mfn_to_page(smfn);
if ( sp->u.sh.count != 1 || !sp->up )
@@ -2547,6 +2550,7 @@ int sh_safe_not_to_sync(struct vcpu *v,
#if (SHADOW_PAGING_LEVELS == 4)
/* up to l3 */
sp = mfn_to_page(smfn);
+ ASSERT(sh_type_has_up_pointer(v, SH_type_l2_shadow));
if ( sp->u.sh.count != 1 || !sp->up )
return 0;
smfn = _mfn(sp->up >> PAGE_SHIFT);
@@ -2555,17 +2559,10 @@ int sh_safe_not_to_sync(struct vcpu *v,
/* up to l4 */
sp = mfn_to_page(smfn);
if ( sp->u.sh.count != 1
- || sh_type_is_pinnable(v, SH_type_l3_64_shadow) || !sp->up )
+ || !sh_type_has_up_pointer(v, SH_type_l3_64_shadow) || !sp->up )
return 0;
smfn = _mfn(sp->up >> PAGE_SHIFT);
ASSERT(mfn_valid(smfn));
-#endif
-
-#if (GUEST_PAGING_LEVELS == 2 && SHADOW_PAGING_LEVELS == 3)
- /* In 2-on-3 shadow mode the up pointer contains the link to the
- * shadow page, but the shadow_table contains only the first of the
- * four pages that makes the PAE top shadow tables. */
- smfn = _mfn(mfn_x(smfn) & ~0x3UL);
#endif
if ( pagetable_get_pfn(v->arch.shadow_table[0]) == mfn_x(smfn)
diff -r 14fcf5b87344 -r 89d04df0a391 xen/arch/x86/mm/shadow/private.h
--- a/xen/arch/x86/mm/shadow/private.h Wed Sep 01 11:23:47 2010 +0100
+++ b/xen/arch/x86/mm/shadow/private.h Wed Sep 01 11:23:48 2010 +0100
@@ -272,6 +272,17 @@ static inline int sh_type_is_pinnable(st
return 0;
}
+static inline int sh_type_has_up_pointer(struct vcpu *v, unsigned int t)
+{
+ /* Multi-page shadows don't have up-pointers */
+ if ( t == SH_type_l1_32_shadow
+ || t == SH_type_fl1_32_shadow
+ || t == SH_type_l2_32_shadow )
+ return 0;
+ /* Pinnable shadows don't have up-pointers either */
+ return !sh_type_is_pinnable(v, t);
+}
+
/*
* Definitions for the shadow_flags field in page_info.
* These flags are stored on *guest* pages...
@@ -642,7 +653,7 @@ static inline int sh_get_ref(struct vcpu
/* We remember the first shadow entry that points to each shadow. */
if ( entry_pa != 0
- && !sh_type_is_pinnable(v, sp->u.sh.type)
+ && sh_type_has_up_pointer(v, sp->u.sh.type)
&& sp->up == 0 )
sp->up = entry_pa;
@@ -663,7 +674,7 @@ static inline void sh_put_ref(struct vcp
/* If this is the entry in the up-pointer, remove it */
if ( entry_pa != 0
- && !sh_type_is_pinnable(v, sp->u.sh.type)
+ && sh_type_has_up_pointer(v, sp->u.sh.type)
&& sp->up == entry_pa )
sp->up = 0;
@@ -684,51 +695,137 @@ static inline void sh_put_ref(struct vcp
sh_destroy_shadow(v, smfn);
}
+
+/* Walk the list of pinned shadows, from the tail forwards,
+ * skipping the non-head-page entries */
+static inline struct page_info *
+prev_pinned_shadow(const struct page_info *page,
+ const struct domain *d)
+{
+ struct page_info *p;
+
+ if ( page == d->arch.paging.shadow.pinned_shadows.next )
+ return NULL;
+
+ if ( page == NULL ) /* If no current place, start at the tail */
+ p = d->arch.paging.shadow.pinned_shadows.tail;
+ else
+ p = pdx_to_page(page->list.prev);
+ /* Skip over the non-tail parts of multi-page shadows */
+ if ( p && p->u.sh.type == SH_type_l2_32_shadow )
+ {
+ p = pdx_to_page(p->list.prev);
+ ASSERT(p && p->u.sh.type == SH_type_l2_32_shadow);
+ p = pdx_to_page(p->list.prev);
+ ASSERT(p && p->u.sh.type == SH_type_l2_32_shadow);
+ p = pdx_to_page(p->list.prev);
+ ASSERT(p && p->u.sh.type == SH_type_l2_32_shadow);
+ }
+ ASSERT(!p || p->u.sh.head);
+ return p;
+}
+
+#define foreach_pinned_shadow(dom, pos, tmp) \
+ for ( pos = prev_pinned_shadow(NULL, (dom)); \
+ pos ? (tmp = prev_pinned_shadow(pos, (dom)), 1) : 0; \
+ pos = tmp )
/* Pin a shadow page: take an extra refcount, set the pin bit,
* and put the shadow at the head of the list of pinned shadows.
* Returns 0 for failure, 1 for success. */
static inline int sh_pin(struct vcpu *v, mfn_t smfn)
{
+ struct page_info *sp;
+ struct page_list_head h, *pin_list;
+
+ ASSERT(mfn_valid(smfn));
+ sp = mfn_to_page(smfn);
+ ASSERT(sh_type_is_pinnable(v, sp->u.sh.type));
+ ASSERT(sp->u.sh.head);
+
+ /* Treat the up-to-four pages of the shadow as a unit in the list ops */
+ h.next = h.tail = sp;
+ if ( sp->u.sh.type == SH_type_l2_32_shadow )
+ {
+ h.tail = pdx_to_page(h.tail->list.next);
+ h.tail = pdx_to_page(h.tail->list.next);
+ h.tail = pdx_to_page(h.tail->list.next);
+ ASSERT(h.tail->u.sh.type == SH_type_l2_32_shadow);
+ }
+ pin_list = &v->domain->arch.paging.shadow.pinned_shadows;
+
+ if ( sp->u.sh.pinned )
+ {
+ /* Already pinned: take it out of the pinned-list so it can go
+ * at the front */
+ if ( pin_list->next == h.next )
+ return 1;
+ page_list_prev(h.next, pin_list)->list.next = h.tail->list.next;
+ if ( pin_list->tail == h.tail )
+ pin_list->tail = page_list_prev(h.next, pin_list);
+ else
+ page_list_next(h.tail, pin_list)->list.prev = h.next->list.prev;
+ h.tail->list.next = h.next->list.prev = PAGE_LIST_NULL;
+ }
+ else
+ {
+ /* Not pinned: pin it! */
+ if ( !sh_get_ref(v, smfn, 0) )
+ return 0;
+ sp->u.sh.pinned = 1;
+ ASSERT(h.next->list.prev == PAGE_LIST_NULL);
+ ASSERT(h.tail->list.next == PAGE_LIST_NULL);
+ }
+ /* Put it at the head of the list of pinned shadows */
+ page_list_splice(&h, pin_list);
+ return 1;
+}
+
+/* Unpin a shadow page: unset the pin bit, take the shadow off the list
+ * of pinned shadows, and release the extra ref. */
+static inline void sh_unpin(struct vcpu *v, mfn_t smfn)
+{
+ struct page_list_head h, *pin_list;
struct page_info *sp;
ASSERT(mfn_valid(smfn));
sp = mfn_to_page(smfn);
ASSERT(sh_type_is_pinnable(v, sp->u.sh.type));
- if ( sp->u.sh.pinned )
- {
- /* Already pinned: take it out of the pinned-list so it can go
- * at the front */
- page_list_del(sp, &v->domain->arch.paging.shadow.pinned_shadows);
- }
- else
- {
- /* Not pinned: pin it! */
- if ( !sh_get_ref(v, smfn, 0) )
- return 0;
- sp->u.sh.pinned = 1;
- }
- /* Put it at the head of the list of pinned shadows */
- page_list_add(sp, &v->domain->arch.paging.shadow.pinned_shadows);
- return 1;
-}
-
-/* Unpin a shadow page: unset the pin bit, take the shadow off the list
- * of pinned shadows, and release the extra ref. */
-static inline void sh_unpin(struct vcpu *v, mfn_t smfn)
-{
- struct page_info *sp;
+ ASSERT(sp->u.sh.head);
+
+ /* Treat the up-to-four pages of the shadow as a unit in the list ops */
+ h.next = h.tail = sp;
+ if ( sp->u.sh.type == SH_type_l2_32_shadow )
+ {
+ h.tail = pdx_to_page(h.tail->list.next);
+ h.tail = pdx_to_page(h.tail->list.next);
+ h.tail = pdx_to_page(h.tail->list.next);
+ ASSERT(h.tail->u.sh.type == SH_type_l2_32_shadow);
+ }
+ pin_list = &v->domain->arch.paging.shadow.pinned_shadows;
+
+ if ( !sp->u.sh.pinned )
+ return;
+
+ sp->u.sh.pinned = 0;
+
+ /* Cut the sub-list out of the list of pinned shadows */
+ if ( pin_list->next == h.next && pin_list->tail == h.tail )
+ pin_list->next = pin_list->tail = NULL;
+ else
+ {
+ if ( pin_list->next == h.next )
+ pin_list->next = page_list_next(h.tail, pin_list);
+ else
+ page_list_prev(h.next, pin_list)->list.next = h.tail->list.next;
+ if ( pin_list->tail == h.tail )
+ pin_list->tail = page_list_prev(h.next, pin_list);
+ else
+ page_list_next(h.tail, pin_list)->list.prev = h.next->list.prev;
+ }
+ h.tail->list.next = h.next->list.prev = PAGE_LIST_NULL;
- ASSERT(mfn_valid(smfn));
- sp = mfn_to_page(smfn);
- ASSERT(sh_type_is_pinnable(v, sp->u.sh.type));
- if ( sp->u.sh.pinned )
- {
- sp->u.sh.pinned = 0;
- page_list_del(sp, &v->domain->arch.paging.shadow.pinned_shadows);
- sp->up = 0; /* in case this stops being a pinnable type in future */
- sh_put_ref(v, smfn, 0);
- }
+ sh_put_ref(v, smfn, 0);
}
diff -r 14fcf5b87344 -r 89d04df0a391 xen/include/asm-x86/mm.h
--- a/xen/include/asm-x86/mm.h Wed Sep 01 11:23:47 2010 +0100
+++ b/xen/include/asm-x86/mm.h Wed Sep 01 11:23:48 2010 +0100
@@ -35,13 +35,18 @@ struct page_info
union {
/* Each frame can be threaded onto a doubly-linked list.
*
- * For unused shadow pages, a list of pages of this order; for
- * pinnable shadows, if pinned, a list of other pinned shadows
- * (see sh_type_is_pinnable() below for the definition of
- * "pinnable" shadow types).
+ * For unused shadow pages, a list of pages of this order;
+ * for multi-page shadows, links to the other pages in this shadow;
+ * for pinnable shadows, if pinned, a list of all pinned shadows
+ * (see sh_type_is_pinnable() for the definition of "pinnable"
+ * shadow types). N.B. a shadow may be both pinnable and multi-page.
+ * In that case the pages are inserted in order in the list of
+ * pinned shadows and walkers of that list must be prepared
+ * to keep them all together during updates.
*/
struct page_list_entry list;
- /* For non-pinnable shadows, a higher entry that points at us. */
+ /* For non-pinnable single-page shadows, a higher entry that points
+ * at us. */
paddr_t up;
/* For shared/sharable pages the sharing handle */
uint64_t shr_handle;
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