Commit 404381c5 authored Feb 24, 2014 by Marcelo Tosatti Committed by Paolo Bonzini Feb 26, 2014

KVM: MMU: drop read-only large sptes when creating lower level sptes



Read-only large sptes can be created due to read-only faults as
follows:

- QEMU pagetable entry that maps guest memory is read-only
due to COW.
- Guest read faults such memory, COW is not broken, because
it is a read-only fault.
- Enable dirty logging, large spte not nuked because it is read-only.
- Write-fault on such memory causes guest to loop endlessly
(which must go down to level 1 because dirty logging is enabled).

Fix by dropping large spte when necessary.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

parent 6d0abeca

arch/x86/kvm/mmu.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -2672,6 +2672,7 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
		break;
		}

		drop_large_spte(vcpu, iterator.sptep);
		if (!is_shadow_present_pte(*iterator.sptep)) {
		u64 base_addr = iterator.addr;

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