KVM: SVM: Add xsetbv intercept
This patch implements the xsetbv intercept to the AMD part
of KVM. This makes AVX usable in a save way for the guest on
AVX capable AMD hardware.
The patch is tested by using AVX in the guest and host in
parallel and checking for data corruption. I also used the
KVM xsave unit-tests and they all pass.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 4dbc372..73461b1 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -935,6 +935,7 @@
set_intercept(svm, INTERCEPT_WBINVD);
set_intercept(svm, INTERCEPT_MONITOR);
set_intercept(svm, INTERCEPT_MWAIT);
+ set_intercept(svm, INTERCEPT_XSETBV);
control->iopm_base_pa = iopm_base;
control->msrpm_base_pa = __pa(svm->msrpm);
@@ -2546,6 +2547,19 @@
return 1;
}
+static int xsetbv_interception(struct vcpu_svm *svm)
+{
+ u64 new_bv = kvm_read_edx_eax(&svm->vcpu);
+ u32 index = kvm_register_read(&svm->vcpu, VCPU_REGS_RCX);
+
+ if (kvm_set_xcr(&svm->vcpu, index, new_bv) == 0) {
+ svm->next_rip = kvm_rip_read(&svm->vcpu) + 3;
+ skip_emulated_instruction(&svm->vcpu);
+ }
+
+ return 1;
+}
+
static int invalid_op_interception(struct vcpu_svm *svm)
{
kvm_queue_exception(&svm->vcpu, UD_VECTOR);
@@ -2971,6 +2985,7 @@
[SVM_EXIT_WBINVD] = emulate_on_interception,
[SVM_EXIT_MONITOR] = invalid_op_interception,
[SVM_EXIT_MWAIT] = invalid_op_interception,
+ [SVM_EXIT_XSETBV] = xsetbv_interception,
[SVM_EXIT_NPF] = pf_interception,
};
@@ -3624,10 +3639,6 @@
static void svm_set_supported_cpuid(u32 func, struct kvm_cpuid_entry2 *entry)
{
switch (func) {
- case 0x00000001:
- /* Mask out xsave bit as long as it is not supported by SVM */
- entry->ecx &= ~(bit(X86_FEATURE_XSAVE));
- break;
case 0x80000001:
if (nested)
entry->ecx |= (1 << 2); /* Set SVM bit */
@@ -3701,6 +3712,7 @@
{ SVM_EXIT_WBINVD, "wbinvd" },
{ SVM_EXIT_MONITOR, "monitor" },
{ SVM_EXIT_MWAIT, "mwait" },
+ { SVM_EXIT_XSETBV, "xsetbv" },
{ SVM_EXIT_NPF, "npf" },
{ -1, NULL }
};