KVM: SVM: Add support for AMD's OSVW feature in guests

In some cases guests should not provide workarounds for errata even when the
physical processor is affected. For example, because of erratum 400 on family
10h processors a Linux guest will read an MSR (resulting in VMEXIT) before
going to idle in order to avoid getting stuck in a non-C0 state. This is not
necessary: HLT and IO instructions are intercepted and therefore there is no
reason for erratum 400 workaround in the guest.

This patch allows us to present a guest with certain errata as fixed,
regardless of the state of actual hardware.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a3ce196d21fe..2bd77a3a41ed 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1675,6 +1675,16 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data)
                  */
                 pr_unimpl(vcpu, "ignored wrmsr: 0x%x data %llx\n", msr, data);
                 break;
+        case MSR_AMD64_OSVW_ID_LENGTH:
+                if (!guest_cpuid_has_osvw(vcpu))
+                        return 1;
+                vcpu->arch.osvw.length = data;
+                break;
+        case MSR_AMD64_OSVW_STATUS:
+                if (!guest_cpuid_has_osvw(vcpu))
+                        return 1;
+                vcpu->arch.osvw.status = data;
+                break;
         default:
                 if (msr && (msr == vcpu->kvm->arch.xen_hvm_config.msr))
                         return xen_hvm_config(vcpu, data);
@@ -1959,6 +1969,16 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
                  */
                 data = 0xbe702111;
                 break;
+        case MSR_AMD64_OSVW_ID_LENGTH:
+                if (!guest_cpuid_has_osvw(vcpu))
+                        return 1;
+                data = vcpu->arch.osvw.length;
+                break;
+        case MSR_AMD64_OSVW_STATUS:
+                if (!guest_cpuid_has_osvw(vcpu))
+                        return 1;
+                data = vcpu->arch.osvw.status;
+                break;
         default:
                 if (kvm_pmu_msr(vcpu, msr))
                         return kvm_pmu_get_msr(vcpu, msr, pdata);