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| author | Maxim Levitsky <mlevitsk@redhat.com> | 2021-09-14 18:48:23 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-10-01 03:44:46 -0400 |
| commit | f800650a4ed2f4e99d3333b1f5b50c591f559ed0 (patch) | |
| tree | 1337d401105c723ab0b54a535860fac9657dc924 /arch/x86 | |
| parent | 36e8194dcd749c2455d0fcbad43e719699691a11 (diff) | |
| download | linux-f800650a4ed2f4e99d3333b1f5b50c591f559ed0.tar.gz | |
KVM: x86: SVM: add module param to control TSC scaling
This allows to easily simulate a CPU without this feature. Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> Message-Id: <20210914154825.104886-13-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/svm/svm.c | 24 |
1 files changed, 18 insertions, 6 deletions
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); |