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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen-unstable] x86 shadow: remove the assumption that multipage shadows are contiguous
# HG changeset patch
# User Tim Deegan <Tim.Deegan@xxxxxxxxxx>
# Date 1283336628 -3600
# Node ID ec9caff0adc6331bbe07581d7953950f1ff4eaeb
# Parent 89d04df0a39153bfe0522e1c3c5c0ac0458b8a9b
x86 shadow: remove the assumption that multipage shadows are contiguous
and move from page to page using the linked list instead.
Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
---
xen/arch/x86/mm/shadow/common.c | 4 +-
xen/arch/x86/mm/shadow/multi.c | 69 +++++++++++++++++++++++-----------------
2 files changed, 42 insertions(+), 31 deletions(-)
diff -r 89d04df0a391 -r ec9caff0adc6 xen/arch/x86/mm/shadow/common.c
--- a/xen/arch/x86/mm/shadow/common.c Wed Sep 01 11:23:48 2010 +0100
+++ b/xen/arch/x86/mm/shadow/common.c Wed Sep 01 11:23:48 2010 +0100
@@ -1214,8 +1214,8 @@ int shadow_cmpxchg_guest_entry(struct vc
* l1 tables (covering 2MB of virtual address space each). Similarly, a
* 32-bit guest l2 table (4GB va) needs to be shadowed by four
* PAE/64-bit l2 tables (1GB va each). These multi-page shadows are
- * contiguous and aligned; functions for handling offsets into them are
- * defined in shadow.c (shadow_l1_index() etc.)
+ * not contiguous in memory; functions for handling offsets into them are
+ * defined in shadow/multi.c (shadow_l1_index() etc.)
*
* This table shows the allocation behaviour of the different modes:
*
diff -r 89d04df0a391 -r ec9caff0adc6 xen/arch/x86/mm/shadow/multi.c
--- a/xen/arch/x86/mm/shadow/multi.c Wed Sep 01 11:23:48 2010 +0100
+++ b/xen/arch/x86/mm/shadow/multi.c Wed Sep 01 11:23:48 2010 +0100
@@ -421,13 +421,27 @@ sh_guest_get_eff_l1e(struct vcpu *v, uns
* way to see this is: a 32-bit guest L2 page maps 4GB of virtual address
* space, while a PAE- or 64-bit shadow L2 page maps 1GB of virtual address
* space.)
- *
- * For PAE guests, for every 32-bytes of guest L3 page table, we use 64-bytes
- * of shadow (to store both the shadow, and the info that would normally be
- * stored in page_info fields). This arrangement allows the shadow and the
- * "page_info" fields to always be stored in the same page (in fact, in
- * the same cache line), avoiding an extra call to map_domain_page().
*/
+
+/* From one page of a multi-page shadow, find the next one */
+static inline mfn_t sh_next_page(mfn_t smfn)
+{
+ mfn_t next;
+ struct page_info *pg = mfn_to_page(smfn);
+
+ ASSERT(pg->u.sh.type == SH_type_l1_32_shadow
+ || pg->u.sh.type == SH_type_fl1_32_shadow
+ || pg->u.sh.type == SH_type_l2_32_shadow);
+ ASSERT(pg->u.sh.type == SH_type_l2_32_shadow || pg->u.sh.head);
+ ASSERT(pg->list.next != PAGE_LIST_NULL);
+
+ next = _mfn(pdx_to_pfn(pg->list.next));
+
+ /* XXX not for long */ ASSERT(mfn_x(next) == mfn_x(smfn) + 1);
+ ASSERT(mfn_to_page(next)->u.sh.type == pg->u.sh.type);
+ ASSERT(!mfn_to_page(next)->u.sh.head);
+ return next;
+}
static inline u32
guest_index(void *ptr)
@@ -440,8 +454,8 @@ shadow_l1_index(mfn_t *smfn, u32 guest_i
{
#if (GUEST_PAGING_LEVELS == 2)
ASSERT(mfn_to_page(*smfn)->u.sh.head);
- *smfn = _mfn(mfn_x(*smfn) +
- (guest_index / SHADOW_L1_PAGETABLE_ENTRIES));
+ if ( guest_index >= SHADOW_L1_PAGETABLE_ENTRIES )
+ *smfn = sh_next_page(*smfn);
return (guest_index % SHADOW_L1_PAGETABLE_ENTRIES);
#else
return guest_index;
@@ -452,13 +466,12 @@ shadow_l2_index(mfn_t *smfn, u32 guest_i
shadow_l2_index(mfn_t *smfn, u32 guest_index)
{
#if (GUEST_PAGING_LEVELS == 2)
+ int i;
ASSERT(mfn_to_page(*smfn)->u.sh.head);
// Because we use 2 shadow l2 entries for each guest entry, the number of
// guest entries per shadow page is SHADOW_L2_PAGETABLE_ENTRIES/2
- //
- *smfn = _mfn(mfn_x(*smfn) +
- (guest_index / (SHADOW_L2_PAGETABLE_ENTRIES / 2)));
-
+ for ( i = 0; i < guest_index / (SHADOW_L2_PAGETABLE_ENTRIES / 2); i++ )
+ *smfn = sh_next_page(*smfn);
// We multiply by two to get the index of the first of the two entries
// used to shadow the specified guest entry.
return (guest_index % (SHADOW_L2_PAGETABLE_ENTRIES / 2)) * 2;
@@ -1014,11 +1027,11 @@ static int shadow_set_l2e(struct vcpu *v
/* In 2-on-3 we work with pairs of l2es pointing at two-page
* shadows. Reference counting and up-pointers track from the first
* page of the shadow to the first l2e, so make sure that we're
- * working with those:
- * Align the pointer down so it's pointing at the first of the pair */
+ * working with those:
+ * Start with a pair of identical entries */
+ shadow_l2e_t pair[2] = { new_sl2e, new_sl2e };
+ /* Align the pointer down so it's pointing at the first of the pair */
sl2e = (shadow_l2e_t *)((unsigned long)sl2e & ~(sizeof(shadow_l2e_t)));
- /* Align the mfn of the shadow entry too */
- new_sl2e.l2 &= ~(1<<PAGE_SHIFT);
#endif
ASSERT(sl2e != NULL);
@@ -1055,19 +1068,16 @@ static int shadow_set_l2e(struct vcpu *v
sh_resync(v, gl1mfn);
}
#endif
+#if GUEST_PAGING_LEVELS == 2
+ /* Update the second entry to point tio the second half of the l1 */
+ sl1mfn = sh_next_page(sl1mfn);
+ pair[1] = shadow_l2e_from_mfn(sl1mfn, shadow_l2e_get_flags(new_sl2e));
+#endif
}
/* Write the new entry */
#if GUEST_PAGING_LEVELS == 2
- {
- shadow_l2e_t pair[2] = { new_sl2e, new_sl2e };
- /* The l1 shadow is two pages long and need to be pointed to by
- * two adjacent l1es. The pair have the same flags, but point
- * at odd and even MFNs */
- ASSERT(!(pair[0].l2 & (1<<PAGE_SHIFT)));
- pair[1].l2 |= (1<<PAGE_SHIFT);
- shadow_write_entries(sl2e, &pair, 2, sl2mfn);
- }
+ shadow_write_entries(sl2e, &pair, 2, sl2mfn);
#else /* normal case */
shadow_write_entries(sl2e, &new_sl2e, 1, sl2mfn);
#endif
@@ -1301,7 +1311,7 @@ do {
int __done = 0; \
_SHADOW_FOREACH_L1E(_sl1mfn, _sl1e, _gl1p, \
({ (__done = _done); }), _code); \
- _sl1mfn = _mfn(mfn_x(_sl1mfn) + 1); \
+ _sl1mfn = sh_next_page(_sl1mfn); \
if ( !__done ) \
_SHADOW_FOREACH_L1E(_sl1mfn, _sl1e, _gl1p, \
({ (__done = _done); }), _code); \
@@ -1335,7 +1345,7 @@ do {
increment_ptr_to_guest_entry(_gl2p); \
} \
sh_unmap_domain_page(_sp); \
- _sl2mfn = _mfn(mfn_x(_sl2mfn) + 1); \
+ if ( _j < 3 ) _sl2mfn = sh_next_page(_sl2mfn); \
} \
} while (0)
@@ -4332,13 +4342,14 @@ sh_update_cr3(struct vcpu *v, int do_loc
///
#if SHADOW_PAGING_LEVELS == 3
{
- mfn_t smfn;
+ mfn_t smfn = pagetable_get_mfn(v->arch.shadow_table[0]);
int i;
for ( i = 0; i < 4; i++ )
{
#if GUEST_PAGING_LEVELS == 2
/* 2-on-3: make a PAE l3 that points at the four-page l2 */
- smfn = _mfn(pagetable_get_pfn(v->arch.shadow_table[0]) + i);
+ if ( i != 0 )
+ smfn = sh_next_page(smfn);
#else
/* 3-on-3: make a PAE l3 that points at the four l2 pages */
smfn = pagetable_get_mfn(v->arch.shadow_table[i]);
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