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KVM: MMU: only write protect mappings at pagetable level

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If a pagetable contains a writeable large spte, all of its sptes will be
write protected, including non-leaf ones, leading to endless pagefaults.

Do not write protect pages above PT_PAGE_TABLE_LEVEL, as the spte fault
paths assume non-leaf sptes are writable.

Tested-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Marcelo Tosatti 2010-12-22 09:01:57 -02:00 committed by Avi Kivity
parent 16d8f72f70
commit e49146dce8
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kvm/mmu.c
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@ -3445,6 +3445,9 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
if (!test_bit(slot, sp->slot_bitmap))
continue;
if (sp->role.level != PT_PAGE_TABLE_LEVEL)
continue;
pt = sp->spt;
for (i = 0; i < PT64_ENT_PER_PAGE; ++i)
/* avoid RMW */