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Subject[patch 31/48] KVM: x86: check for cr3 validity in mmu_alloc_roots

2.6.27-stable review patch. If anyone has any objections, please let us know.

------------------
From: Marcelo Tosatti <mtosatti@redhat.com>

(cherry picked from commit 8986ecc0ef58c96eec48d8502c048f3ab67fd8e2)

Verify the cr3 address stored in vcpu->arch.cr3 points to an existant
memslot. If not, inject a triple fault.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
arch/x86/kvm/mmu.c | 25 ++++++++++++++++++++++---
arch/x86/kvm/x86.c | 1 +
2 files changed, 23 insertions(+), 3 deletions(-)

--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1350,7 +1350,19 @@ static void mmu_free_roots(struct kvm_vc
vcpu->arch.mmu.root_hpa = INVALID_PAGE;
}

-static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
+static int mmu_check_root(struct kvm_vcpu *vcpu, gfn_t root_gfn)
+{
+ int ret = 0;
+
+ if (!kvm_is_visible_gfn(vcpu->kvm, root_gfn)) {
+ set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests);
+ ret = 1;
+ }
+
+ return ret;
+}
+
+static int mmu_alloc_roots(struct kvm_vcpu *vcpu)
{
int i;
gfn_t root_gfn;
@@ -1365,13 +1377,15 @@ static void mmu_alloc_roots(struct kvm_v
ASSERT(!VALID_PAGE(root));
if (tdp_enabled)
metaphysical = 1;
+ if (mmu_check_root(vcpu, root_gfn))
+ return 1;
sp = kvm_mmu_get_page(vcpu, root_gfn, 0,
PT64_ROOT_LEVEL, metaphysical,
ACC_ALL, NULL);
root = __pa(sp->spt);
++sp->root_count;
vcpu->arch.mmu.root_hpa = root;
- return;
+ return 0;
}
metaphysical = !is_paging(vcpu);
if (tdp_enabled)
@@ -1388,6 +1402,8 @@ static void mmu_alloc_roots(struct kvm_v
root_gfn = vcpu->arch.pdptrs[i] >> PAGE_SHIFT;
} else if (vcpu->arch.mmu.root_level == 0)
root_gfn = 0;
+ if (mmu_check_root(vcpu, root_gfn))
+ return 1;
sp = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
PT32_ROOT_LEVEL, metaphysical,
ACC_ALL, NULL);
@@ -1396,6 +1412,7 @@ static void mmu_alloc_roots(struct kvm_v
vcpu->arch.mmu.pae_root[i] = root | PT_PRESENT_MASK;
}
vcpu->arch.mmu.root_hpa = __pa(vcpu->arch.mmu.pae_root);
+ return 0;
}

static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr)
@@ -1639,8 +1656,10 @@ int kvm_mmu_load(struct kvm_vcpu *vcpu)
goto out;
spin_lock(&vcpu->kvm->mmu_lock);
kvm_mmu_free_some_pages(vcpu);
- mmu_alloc_roots(vcpu);
+ r = mmu_alloc_roots(vcpu);
spin_unlock(&vcpu->kvm->mmu_lock);
+ if (r)
+ goto out;
kvm_x86_ops->set_cr3(vcpu, vcpu->arch.mmu.root_hpa);
kvm_mmu_flush_tlb(vcpu);
out:
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4073,6 +4073,7 @@ int kvm_arch_set_memory_region(struct kv
void kvm_arch_flush_shadow(struct kvm *kvm)
{
kvm_mmu_zap_all(kvm);
+ kvm_reload_remote_mmus(kvm);
}

int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)



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