Section 11.11.2.3 of the SDM mentions "All other bits in the 
IA32_MTRR_PHYSBASEn 
and IA32_MTRR_PHYSMASKn registers are reserved; the processor generates a 
general-protection exception(#GP) if software attempts to write to them". This 
patch do it in kvm.

Signed-off-by: Wanpeng Li <wanpeng...@linux.intel.com>
---
 arch/x86/kvm/x86.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index caaffeb..aa64c70 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1769,11 +1769,22 @@ static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, 
u64 data)
        /* variable MTRRs */
        if (msr >= 0x200 && msr < 0x200 + 2 * KVM_NR_VAR_MTRR) {
                int idx, is_mtrr_mask;
+               u64 mask = 0;
 
                idx = (msr - 0x200) / 2;
                is_mtrr_mask = msr - 0x200 - 2 * idx;
-               if (!is_mtrr_mask)
-                       return valid_mtrr_type(data & 0xff);
+               for (i = 63; i > boot_cpu_data.x86_phys_bits; i--)
+                       mask |= (1ULL << i);
+               if (!is_mtrr_mask) {
+                       if (!valid_mtrr_type(data & 0xff))
+                               return false;
+                       mask |= 0xf00;
+               } else
+                       mask |= 0x7ff;
+               if (data & mask) {
+                       kvm_inject_gp(vcpu, 0);
+                       return false;
+               }
        }
        return true;
 }
-- 
1.9.1

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