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(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 6504e40e0985..001a5af842ba 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -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);