KVM: x86: report valid microcode update ID

Windows Server 2008 SP2 checked build with smp > 1 BSOD's during
boot due to lack of microcode update:

*** Assertion failed: The system BIOS on this machine does not properly
support the processor.  The system BIOS did not load any microcode update.
A BIOS containing the latest microcode update is needed for system reliability.
(CurrentUpdateRevision != 0)
***   Source File: d:\longhorn\base\hals\update\intelupd\update.c, line 440

Report a non-zero microcode update signature to make it happy.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/x86.c

@@ -1842,7 +1842,6 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 
 	switch (msr) {
 	case MSR_IA32_PLATFORM_ID:
-	case MSR_IA32_UCODE_REV:
 	case MSR_IA32_EBL_CR_POWERON:
 	case MSR_IA32_DEBUGCTLMSR:
 	case MSR_IA32_LASTBRANCHFROMIP:
@@ -1863,6 +1862,9 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 	case MSR_FAM10H_MMIO_CONF_BASE:
 		data = 0;
 		break;
+	case MSR_IA32_UCODE_REV:
+		data = 0x100000000ULL;
+		break;
 	case MSR_MTRRcap:
 		data = 0x500 | KVM_NR_VAR_MTRR;
 		break;