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Subject[patch 147/176] KVM: MMU: Fix 32 bit legacy paging with NPT
2.6.36-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Joerg Roedel <joerg.roedel@amd.com>

commit f87f928882d080eaec8b0d76aecff003d664697d upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/x86/kvm/mmu.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2254,6 +2254,10 @@ static int mmu_alloc_roots(struct kvm_vc
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];

@@ -2265,10 +2269,10 @@ static int mmu_alloc_roots(struct kvm_vc
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 - PAGE_SHIFT);



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