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SubjectRe: [PATCH 55/61] KVM: VMX: Directly query Intel PT mode when refreshing PMUs
Date
Sean Christopherson <sean.j.christopherson@intel.com> writes:

> Use vmx_pt_mode_is_host_guest() in intel_pmu_refresh() instead of
> bouncing through kvm_x86_ops->pt_supported, and remove ->pt_supported()
> as the PMU code was the last remaining user.
>
> Opportunistically clean up the wording of a comment that referenced
> kvm_x86_ops->pt_supported().
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/include/asm/kvm_host.h | 2 --
> arch/x86/kvm/svm.c | 7 -------
> arch/x86/kvm/vmx/pmu_intel.c | 2 +-
> arch/x86/kvm/vmx/vmx.c | 6 ------
> arch/x86/kvm/x86.c | 7 +++----
> 5 files changed, 4 insertions(+), 20 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 1dd5ac8a2136..a8bae9d88bce 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1162,8 +1162,6 @@ struct kvm_x86_ops {
> void (*handle_exit_irqoff)(struct kvm_vcpu *vcpu,
> enum exit_fastpath_completion *exit_fastpath);
>
> - bool (*pt_supported)(void);
> -
> int (*check_nested_events)(struct kvm_vcpu *vcpu, bool external_intr);
> void (*request_immediate_exit)(struct kvm_vcpu *vcpu);
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 6dd9c810c0dc..a27f83f7521c 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_pt_supported(void)
> -{
> - return false;
> -}
> -
> static bool svm_has_wbinvd_exit(void)
> {
> return true;
> @@ -7438,8 +7433,6 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
>
> .cpuid_update = svm_cpuid_update,
>
> - .pt_supported = svm_pt_supported,
> -
> .set_supported_cpuid = svm_set_supported_cpuid,
>
> .has_wbinvd_exit = svm_has_wbinvd_exit,
> diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
> index 34a3a17bb6d7..d8f5cb312b9d 100644
> --- a/arch/x86/kvm/vmx/pmu_intel.c
> +++ b/arch/x86/kvm/vmx/pmu_intel.c
> @@ -330,7 +330,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
> pmu->global_ovf_ctrl_mask = pmu->global_ctrl_mask
> & ~(MSR_CORE_PERF_GLOBAL_OVF_CTRL_OVF_BUF |
> MSR_CORE_PERF_GLOBAL_OVF_CTRL_COND_CHGD);
> - if (kvm_x86_ops->pt_supported())
> + if (vmx_pt_mode_is_host_guest())
> pmu->global_ovf_ctrl_mask &=
> ~MSR_CORE_PERF_GLOBAL_OVF_CTRL_TRACE_TOPA_PMI;
>
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 98d54cfa0cbe..e6284b6aac56 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -6283,11 +6283,6 @@ static bool vmx_has_emulated_msr(int index)
> }
> }
>
> -static bool vmx_pt_supported(void)
> -{
> - return vmx_pt_mode_is_host_guest();
> -}
> -
> static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
> {
> u32 exit_intr_info;
> @@ -7876,7 +7871,6 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
>
> .check_intercept = vmx_check_intercept,
> .handle_exit_irqoff = vmx_handle_exit_irqoff,
> - .pt_supported = vmx_pt_supported,
>
> .request_immediate_exit = vmx_request_immediate_exit,
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 9d38dcdbb613..144143a57d0b 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -2805,10 +2805,9 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
> !guest_cpuid_has(vcpu, X86_FEATURE_XSAVES))
> return 1;
> /*
> - * We do support PT if kvm_x86_ops->pt_supported(), but we do
> - * not support IA32_XSS[bit 8]. Guests will have to use
> - * RDMSR/WRMSR rather than XSAVES/XRSTORS to save/restore PT
> - * MSRs.
> + * KVM supports exposing PT to the guest, but does not support
> + * IA32_XSS[bit 8]. Guests have to use RDMSR/WRMSR rather than
> + * XSAVES/XRSTORS to save/restore PT MSRs.

So the responsibility shifts from vague 'we' to KVM. There should be
a juridical term for that :-)

> */
> if (data != 0)
> return 1;

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

--
Vitaly

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