KVM: Handle cpuid in the kernel instead of punting to userspace
KVM used to handle cpuid by letting userspace decide what values to
return to the guest. We now handle cpuid completely in the kernel. We
still let userspace decide which values the guest will see by having
userspace set up the value table beforehand (this is necessary to allow
management software to set the cpu features to the least common denominator,
so that live migration can work).
The motivation for the change is that kvm kernel code can be impacted by
cpuid features, for example the x86 emulator.
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 4d5f40f..71410a6 100644
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1585,8 +1585,8 @@
static int handle_cpuid(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
{
- kvm_run->exit_reason = KVM_EXIT_CPUID;
- return 0;
+ kvm_emulate_cpuid(vcpu);
+ return 1;
}
static int handle_rdmsr(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)