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Subject[PATCH] KVM: x86: restrict maximal physical address
Date
The guest could have configured a maximal physical address that exceeds
the host. Prevent that situation as it could easily lead to a bug.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
---
arch/x86/kvm/cpuid.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 25f0f15fab1a..aed910e9fbed 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -136,7 +136,13 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
((best->eax & 0xff00) >> 8) != 0)
return -EINVAL;

- /* Update physical-address width */
+
+ /*
+ * Update physical-address width.
+ * Make sure that it does not exceed hardware capabilities.
+ */
+ if (cpuid_query_maxphyaddr(vcpu) > boot_cpu_data.x86_phys_bits)
+ return -EINVAL;
vcpu->arch.maxphyaddr = cpuid_query_maxphyaddr(vcpu);

kvm_pmu_refresh(vcpu);
--
2.10.2
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