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KVM: MMU: Fix 32 bit legacy paging with NPT

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This patch fixes 32 bit legacy paging with NPT enabled. The
mmu_check_root call on the top-level of the loop causes
root_gfn to take values (in the tdp_enabled path) which are
outside of guest memory. So the mmu_check_root call fails at
some point in the loop interation causing the guest to
tiple-fault.
This patch changes the mmu_check_root calls to the places
where they are really necessary. As a side-effect it
introduces a check for the root of a pae page table too.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Joerg Roedel 2010-09-02 17:29:45 +02:00 committed by Avi Kivity
parent 26e673c300
commit f87f928882
1 changed files with 6 additions and 2 deletions
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8
arch/x86/kvm/mmu.c
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@ -2387,6 +2387,10 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
return 0;
}
direct = !is_paging(vcpu);
if (mmu_check_root(vcpu, root_gfn))
return 1;
for (i = 0; i < 4; ++i) {
hpa_t root = vcpu->arch.mmu.pae_root[i];
@ -2398,10 +2402,10 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
continue;
}
root_gfn = pdptr >> PAGE_SHIFT;
if (mmu_check_root(vcpu, root_gfn))
return 1;
} else if (vcpu->arch.mmu.root_level == 0)
root_gfn = 0;
if (mmu_check_root(vcpu, root_gfn))
return 1;
if (tdp_enabled) {
direct = 1;
root_gfn = i << 30;