KVM: x86: Emulate MSR_EBC_FREQUENCY_ID
Some operating systems store data about the host processor at the
time of installation, and when booted on a more uptodate cpu tries
to read MSR_EBC_FREQUENCY_ID. This has been found with XP.
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f47db25..9d43477 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1651,6 +1651,20 @@
case 0xcd: /* fsb frequency */
data = 3;
break;
+ /*
+ * MSR_EBC_FREQUENCY_ID
+ * Conservative value valid for even the basic CPU models.
+ * Models 0,1: 000 in bits 23:21 indicating a bus speed of
+ * 100MHz, model 2 000 in bits 18:16 indicating 100MHz,
+ * and 266MHz for model 3, or 4. Set Core Clock
+ * Frequency to System Bus Frequency Ratio to 1 (bits
+ * 31:24) even though these are only valid for CPU
+ * models > 2, however guests may end up dividing or
+ * multiplying by zero otherwise.
+ */
+ case MSR_EBC_FREQUENCY_ID:
+ data = 1 << 24;
+ break;
case MSR_IA32_APICBASE:
data = kvm_get_apic_base(vcpu);
break;