@@ -191,6 +191,9 @@ static int lbrv = true;
module_param(lbrv, int, 0444);
+static int tsc_scaling = true;
+module_param(tsc_scaling, int, 0444);
+
/*
* enable / disable AVIC. Because the defaults differ for APICv
* support between VMX and SVM we cannot use module_param_named.
@@ -471,7 +474,7 @@ static int has_svm(void)
static void svm_hardware_disable(void)
{
/* Make sure we clean up behind us */
- if (static_cpu_has(X86_FEATURE_TSCRATEMSR))
+ if (tsc_scaling)
wrmsrl(MSR_AMD64_TSC_RATIO, TSC_RATIO_DEFAULT);
cpu_svm_disable();
@@ -514,6 +517,10 @@ static int svm_hardware_enable(void)
wrmsrl(MSR_VM_HSAVE_PA, __sme_page_pa(sd->save_area));
if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) {
+ /*
+ * Set the default value, even if we don't use TSC scaling
+ * to avoid having stale value in the msr
+ */
wrmsrl(MSR_AMD64_TSC_RATIO, TSC_RATIO_DEFAULT);
__this_cpu_write(current_tsc_ratio, TSC_RATIO_DEFAULT);
}
@@ -1063,10 +1070,15 @@ static __init int svm_hardware_setup(void)
if (boot_cpu_has(X86_FEATURE_FXSR_OPT))
kvm_enable_efer_bits(EFER_FFXSR);
- if (boot_cpu_has(X86_FEATURE_TSCRATEMSR)) {
- kvm_has_tsc_control = true;
- kvm_max_tsc_scaling_ratio = TSC_RATIO_MAX;
- kvm_tsc_scaling_ratio_frac_bits = 32;
+ if (tsc_scaling) {
+ if (!boot_cpu_has(X86_FEATURE_TSCRATEMSR)) {
+ tsc_scaling = false;
+ } else {
+ pr_info("TSC scaling supported\n");
+ kvm_has_tsc_control = true;
+ kvm_max_tsc_scaling_ratio = TSC_RATIO_MAX;
+ kvm_tsc_scaling_ratio_frac_bits = 32;
+ }
}
tsc_aux_uret_slot = kvm_add_user_return_msr(MSR_TSC_AUX);
@@ -1543,7 +1555,7 @@ static void svm_prepare_guest_switch(struct kvm_vcpu *vcpu)
vmsave(__sme_page_pa(sd->save_area));
}
- if (static_cpu_has(X86_FEATURE_TSCRATEMSR)) {
+ if (tsc_scaling) {
u64 tsc_ratio = vcpu->arch.tsc_scaling_ratio;
if (tsc_ratio != __this_cpu_read(current_tsc_ratio)) {
__this_cpu_write(current_tsc_ratio, tsc_ratio);
This allows to easily simulate a CPU without this feature. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> --- arch/x86/kvm/svm/svm.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-)