KVM: vmx: Inject #GP on invalid PAT CR

Guest which sets the PAT CR to invalid value should get a #GP.  Currently, if
vmx supports loading PAT CR during entry, then the value is not checked.  This
patch makes the required check in that case.
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/vmx.c

@@ -2626,6 +2626,8 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		break;
 	case MSR_IA32_CR_PAT:
 		if (vmcs_config.vmentry_ctrl & VM_ENTRY_LOAD_IA32_PAT) {
+			if (!kvm_mtrr_valid(vcpu, MSR_IA32_CR_PAT, data))
+				return 1;
 			vmcs_write64(GUEST_IA32_PAT, data);
 			vcpu->arch.pat = data;
 			break;

arch/x86/kvm/x86.c

@@ -1726,7 +1726,7 @@ static bool valid_mtrr_type(unsigned t)
 	return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
 }
 
-static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
 	int i;
 	u64 mask;
@@ -1769,12 +1769,13 @@ static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 
 	return true;
 }
+EXPORT_SYMBOL_GPL(kvm_mtrr_valid);
 
 static int set_msr_mtrr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 {
 	u64 *p = (u64 *)&vcpu->arch.mtrr_state.fixed_ranges;
 
-	if (!mtrr_valid(vcpu, msr, data))
+	if (!kvm_mtrr_valid(vcpu, msr, data))
 		return 1;
 
 	if (msr == MSR_MTRRdefType) {

arch/x86/kvm/x86.h

@@ -159,6 +159,8 @@ int kvm_write_guest_virt_system(struct x86_emulate_ctxt *ctxt,
 	gva_t addr, void *val, unsigned int bytes,
 	struct x86_exception *exception);
 
+bool kvm_mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data);
+
 #define KVM_SUPPORTED_XCR0     (XSTATE_FP | XSTATE_SSE | XSTATE_YMM \
 				| XSTATE_BNDREGS | XSTATE_BNDCSR)
 extern u64 host_xcr0;