Re: [PATCH 52/61] KVM: x86: Use KVM cpu caps to detect MSR_TSC_AUX virt support

From: Vitaly Kuznetsov
Date: Tue Feb 25 2020 - 09:08:56 EST


Sean Christopherson <sean.j.christopherson@xxxxxxxxx> writes:

> Check for MSR_TSC_AUX virtualization via kvm_cpu_cap_has() and drop
> ->rdtscp_supported().
>
> Note, vmx_rdtscp_supported() needs to hang around a tiny bit longer due
> other usage in VMX code.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 1 -
> arch/x86/kvm/svm.c | 6 ------
> arch/x86/kvm/vmx/vmx.c | 3 ---
> arch/x86/kvm/x86.c | 2 +-
> 4 files changed, 1 insertion(+), 11 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 113b138a0347..1dd5ac8a2136 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1143,7 +1143,6 @@ struct kvm_x86_ops {
> int (*get_tdp_level)(struct kvm_vcpu *vcpu);
> u64 (*get_mt_mask)(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio);
> int (*get_lpage_level)(void);
> - bool (*rdtscp_supported)(void);
>
> void (*set_tdp_cr3)(struct kvm_vcpu *vcpu, unsigned long cr3);
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index f4434816dcdf..6dd9c810c0dc 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -6074,11 +6074,6 @@ static int svm_get_lpage_level(void)
> return PT_PDPE_LEVEL;
> }
>
> -static bool svm_rdtscp_supported(void)
> -{
> - return boot_cpu_has(X86_FEATURE_RDTSCP);
> -}
> -
> static bool svm_pt_supported(void)
> {
> return false;
> @@ -7443,7 +7438,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
>
> .cpuid_update = svm_cpuid_update,
>
> - .rdtscp_supported = svm_rdtscp_supported,
> .pt_supported = svm_pt_supported,
>
> .set_supported_cpuid = svm_set_supported_cpuid,
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 2a1df1b714db..c3577f11f538 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -7870,9 +7870,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
> .get_lpage_level = vmx_get_lpage_level,
>
> .cpuid_update = vmx_cpuid_update,
> -
> - .rdtscp_supported = vmx_rdtscp_supported,
> -
> .set_supported_cpuid = vmx_set_supported_cpuid,
>
> .has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index a6d5f22c7ef6..e4353c03269c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5246,7 +5246,7 @@ static void kvm_init_msr_list(void)
> continue;
> break;
> case MSR_TSC_AUX:
> - if (!kvm_x86_ops->rdtscp_supported())
> + if (!kvm_cpu_cap_has(X86_FEATURE_RDTSCP))
> continue;
> break;
> case MSR_IA32_RTIT_CTL:

Reviewed-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>

--
Vitaly