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KVM: x86: SVM: add module param to control TSC scaling

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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>
This commit is contained in:
Maxim Levitsky 2021-09-14 18:48:23 +03:00 committed by Paolo Bonzini
parent 36e8194dcd
commit f800650a4e
1 changed files with 18 additions and 6 deletions
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24
arch/x86/kvm/svm/svm.c
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@ -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);