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openSUSE:12.2
xen
24883-x86-guest-walk-not-present.patch
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File 24883-x86-guest-walk-not-present.patch of Package xen
References: bnc#747331 # HG changeset patch # User Tim Deegan <tim@xen.org> # Date 1329992967 0 # Node ID adcd6ab160fae996d53c6843da0c5728ca8a8bd3 # Parent 3d4955cbcb67a1c41e6b71af783b0921a3f7b081 x86/mm: Don't check for invalid bits in non-present PTEs. If _PAGE_PRESENT is clean in a pagetable entry, any pattern of bits is valid in the rest of the entry. OSes that special-case PFEC_invalid_bits (since it should never happen) will be confused by our setting it in this way. Signed-off-by: Tim Deegan <tim@xen.org> --- a/xen/arch/x86/mm/guest_walk.c +++ b/xen/arch/x86/mm/guest_walk.c @@ -162,8 +162,11 @@ guest_walk_tables(struct vcpu *v, struct l4p = (guest_l4e_t *) top_map; gw->l4e = l4p[guest_l4_table_offset(va)]; gflags = guest_l4e_get_flags(gw->l4e) ^ iflags; + if ( !(gflags & _PAGE_PRESENT) ) { + rc |= _PAGE_PRESENT; + goto out; + } rc |= ((gflags & mflags) ^ mflags); - if ( rc & _PAGE_PRESENT ) goto out; /* Map the l3 table */ l3p = map_domain_gfn(p2m, @@ -176,9 +179,11 @@ guest_walk_tables(struct vcpu *v, struct /* Get the l3e and check its flags*/ gw->l3e = l3p[guest_l3_table_offset(va)]; gflags = guest_l3e_get_flags(gw->l3e) ^ iflags; - rc |= ((gflags & mflags) ^ mflags); - if ( rc & _PAGE_PRESENT ) + if ( !(gflags & _PAGE_PRESENT) ) { + rc |= _PAGE_PRESENT; goto out; + } + rc |= ((gflags & mflags) ^ mflags); #else /* PAE only... */ @@ -213,9 +218,11 @@ guest_walk_tables(struct vcpu *v, struct #endif /* All levels... */ gflags = guest_l2e_get_flags(gw->l2e) ^ iflags; - rc |= ((gflags & mflags) ^ mflags); - if ( rc & _PAGE_PRESENT ) + if ( !(gflags & _PAGE_PRESENT) ) { + rc |= _PAGE_PRESENT; goto out; + } + rc |= ((gflags & mflags) ^ mflags); pse = (guest_supports_superpages(v) && (guest_l2e_get_flags(gw->l2e) & _PAGE_PSE)); @@ -277,6 +284,10 @@ guest_walk_tables(struct vcpu *v, struct goto out; gw->l1e = l1p[guest_l1_table_offset(va)]; gflags = guest_l1e_get_flags(gw->l1e) ^ iflags; + if ( !(gflags & _PAGE_PRESENT) ) { + rc |= _PAGE_PRESENT; + goto out; + } rc |= ((gflags & mflags) ^ mflags); }
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