commit bc0b99a ("kvm tools: Filter out CPU vendor string") replaced the
processor's native vendor string with a synthetic one to hack around
some interesting guest MSR accesses that were not handled in KVM. In
particular, the MC4_CTL_MASK MSR was accessed for AMD VMs, which isn't
supported by KVM. This MSR relates to masking MCEs originating from the
northbridge on real hardware, but is of zero use in virtualization.
Speaking more broadly, KVM does in fact do the right thing for such an
MSR (#GP), and it is annoying but benign that KVM does a printk for the
MSR. Masking the CPU vendor string is far from ideal, and gets in the
way of testing vendor-specific CPU features. Stop the shenanigans and
expose the vendor ID as returned by KVM_GET_SUPPORTED_CPUID.
Signed-off-by: Oliver Upton <oupton@xxxxxxxxxx>
---
x86/cpuid.c | 8 --------
1 file changed, 8 deletions(-)
diff --git a/x86/cpuid.c b/x86/cpuid.c
index aa213d5..f4347a8 100644
--- a/x86/cpuid.c
+++ b/x86/cpuid.c
@@ -10,7 +10,6 @@
static void filter_cpuid(struct kvm_cpuid2 *kvm_cpuid, int cpu_id)
{
- unsigned int signature[3];
unsigned int i;
/*
@@ -20,13 +19,6 @@ static void filter_cpuid(struct kvm_cpuid2 *kvm_cpuid, int cpu_id)
struct kvm_cpuid_entry2 *entry = &kvm_cpuid->entries[i];
switch (entry->function) {
- case 0:
- /* Vendor name */
- memcpy(signature, "LKVMLKVMLKVM", 12);
- entry->ebx = signature[0];
- entry->ecx = signature[1];
- entry->edx = signature[2];
- break;
case 1:
entry->ebx &= ~(0xff << 24);
entry->ebx |= cpu_id << 24;
--
2.35.1.894.gb6a874cedc-goog
