KVM: Add FFXSR support
AMD K10 CPUs implement the FFXSR feature that gets enabled using
EFER. Let's check if the virtual CPU description includes that
CPUID feature bit and allow enabling it then.
This is required for Windows Server 2008 in Hyper-V mode.
v2 adds CPUID capability exposure
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index db5021b..1c4a018 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -417,6 +417,9 @@
if (boot_cpu_has(X86_FEATURE_NX))
kvm_enable_efer_bits(EFER_NX);
+ if (boot_cpu_has(X86_FEATURE_FXSR_OPT))
+ kvm_enable_efer_bits(EFER_FFXSR);
+
if (nested) {
printk(KERN_INFO "kvm: Nested Virtualization enabled\n");
kvm_enable_efer_bits(EFER_SVME);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 32e3a7e..8f83590 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -490,6 +490,17 @@
return;
}
+ if (efer & EFER_FFXSR) {
+ struct kvm_cpuid_entry2 *feat;
+
+ feat = kvm_find_cpuid_entry(vcpu, 0x80000001, 0);
+ if (!feat || !(feat->edx & bit(X86_FEATURE_FXSR_OPT))) {
+ printk(KERN_DEBUG "set_efer: #GP, enable FFXSR w/o CPUID capability\n");
+ kvm_inject_gp(vcpu, 0);
+ return;
+ }
+ }
+
if (efer & EFER_SVME) {
struct kvm_cpuid_entry2 *feat;
@@ -1240,6 +1251,7 @@
#ifdef CONFIG_X86_64
bit(X86_FEATURE_LM) |
#endif
+ bit(X86_FEATURE_FXSR_OPT) |
bit(X86_FEATURE_MMXEXT) |
bit(X86_FEATURE_3DNOWEXT) |
bit(X86_FEATURE_3DNOW);