71 lines
2.2 KiB
Diff
71 lines
2.2 KiB
Diff
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References: bnc#747331
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# HG changeset patch
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# User Tim Deegan <tim@xen.org>
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# Date 1329992967 0
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# Node ID adcd6ab160fae996d53c6843da0c5728ca8a8bd3
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# Parent 3d4955cbcb67a1c41e6b71af783b0921a3f7b081
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x86/mm: Don't check for invalid bits in non-present PTEs.
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If _PAGE_PRESENT is clean in a pagetable entry, any pattern of bits
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is valid in the rest of the entry. OSes that special-case
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PFEC_invalid_bits (since it should never happen) will be confused
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by our setting it in this way.
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Signed-off-by: Tim Deegan <tim@xen.org>
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--- a/xen/arch/x86/mm/guest_walk.c
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+++ b/xen/arch/x86/mm/guest_walk.c
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@@ -162,8 +162,11 @@ guest_walk_tables(struct vcpu *v, struct
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l4p = (guest_l4e_t *) top_map;
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gw->l4e = l4p[guest_l4_table_offset(va)];
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gflags = guest_l4e_get_flags(gw->l4e) ^ iflags;
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+ if ( !(gflags & _PAGE_PRESENT) ) {
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+ rc |= _PAGE_PRESENT;
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+ goto out;
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+ }
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rc |= ((gflags & mflags) ^ mflags);
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- if ( rc & _PAGE_PRESENT ) goto out;
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/* Map the l3 table */
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l3p = map_domain_gfn(p2m,
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@@ -176,9 +179,11 @@ guest_walk_tables(struct vcpu *v, struct
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/* Get the l3e and check its flags*/
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gw->l3e = l3p[guest_l3_table_offset(va)];
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gflags = guest_l3e_get_flags(gw->l3e) ^ iflags;
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- rc |= ((gflags & mflags) ^ mflags);
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- if ( rc & _PAGE_PRESENT )
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+ if ( !(gflags & _PAGE_PRESENT) ) {
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+ rc |= _PAGE_PRESENT;
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goto out;
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+ }
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+ rc |= ((gflags & mflags) ^ mflags);
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#else /* PAE only... */
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@@ -213,9 +218,11 @@ guest_walk_tables(struct vcpu *v, struct
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#endif /* All levels... */
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gflags = guest_l2e_get_flags(gw->l2e) ^ iflags;
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- rc |= ((gflags & mflags) ^ mflags);
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- if ( rc & _PAGE_PRESENT )
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+ if ( !(gflags & _PAGE_PRESENT) ) {
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+ rc |= _PAGE_PRESENT;
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goto out;
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+ }
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+ rc |= ((gflags & mflags) ^ mflags);
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pse = (guest_supports_superpages(v) &&
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(guest_l2e_get_flags(gw->l2e) & _PAGE_PSE));
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@@ -277,6 +284,10 @@ guest_walk_tables(struct vcpu *v, struct
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goto out;
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gw->l1e = l1p[guest_l1_table_offset(va)];
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gflags = guest_l1e_get_flags(gw->l1e) ^ iflags;
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+ if ( !(gflags & _PAGE_PRESENT) ) {
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+ rc |= _PAGE_PRESENT;
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+ goto out;
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+ }
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rc |= ((gflags & mflags) ^ mflags);
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}
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