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KVM: MMU: ignore zapped root pagetables

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Mark zapped root pagetables as invalid and ignore such pages during lookup.

This is a problem with the cr3-target feature, where a zapped root table fools
the faulting code into creating a read-only mapping. The result is a lockup
if the instruction can't be emulated.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Marcelo Tosatti
2008-02-20 14:47:24 -05:00
committed by Avi Kivity
parent 847f0ad8cb
commit 2e53d63acb
5 changed files with 48 additions and 2 deletions
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12
arch/x86/kvm/x86.c
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@@ -2658,6 +2658,10 @@ preempted:
kvm_x86_ops->guest_debug_pre(vcpu);
again:
if (vcpu->requests)
if (test_and_clear_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests))
kvm_mmu_unload(vcpu);
r = kvm_mmu_reload(vcpu);
if (unlikely(r))
goto out;
@@ -2689,6 +2693,14 @@ again:
goto out;
}
if (vcpu->requests)
if (test_bit(KVM_REQ_MMU_RELOAD, &vcpu->requests)) {
local_irq_enable();
preempt_enable();
r = 1;
goto out;
}
if (signal_pending(current)) {
local_irq_enable();
preempt_enable();