diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 53d593016be5..1ff904653a3e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -190,6 +190,9 @@ module_param(vgif, int, 0444); 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. @@ -470,7 +473,7 @@ 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(); @@ -513,6 +516,10 @@ 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); } @@ -980,10 +987,15 @@ 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); @@ -1496,7 +1508,7 @@ 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);