linux-kernel - Re: [PATCH v4 25/38] KVM: x86/pmu: Add AMD PMU registers to direct access list

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Message-ID: <aCc_Xh4hSCL4eVV8@google.com>
Date: Fri, 16 May 2025 06:36:30 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Mingwei Zhang <mizhang@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Paolo Bonzini <pbonzini@...hat.com>, Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, Liang@...gle.com, 
	Kan <kan.liang@...ux.intel.com>, "H. Peter Anvin" <hpa@...or.com>, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	kvm@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	Yongwei Ma <yongwei.ma@...el.com>, Xiong Zhang <xiong.y.zhang@...ux.intel.com>, 
	Dapeng Mi <dapeng1.mi@...ux.intel.com>, Jim Mattson <jmattson@...gle.com>, 
	Sandipan Das <sandipan.das@....com>, Zide Chen <zide.chen@...el.com>, 
	Eranian Stephane <eranian@...gle.com>, Shukla Manali <Manali.Shukla@....com>, 
	Nikunj Dadhania <nikunj.dadhania@....com>
Subject: Re: [PATCH v4 25/38] KVM: x86/pmu: Add AMD PMU registers to direct
 access list

On Mon, Mar 24, 2025, Mingwei Zhang wrote:
> From: Sandipan Das <sandipan.das@....com>
> 
> Add all PMU-related MSRs (including legacy K7 MSRs) to the list of
> possible direct access MSRs.  Most of them will not be intercepted when
> using passthrough PMU.
> 
> Signed-off-by: Sandipan Das <sandipan.das@....com>
> Signed-off-by: Mingwei Zhang <mizhang@...gle.com>
> ---
>  arch/x86/kvm/svm/svm.c | 24 ++++++++++++++++++++++++
>  arch/x86/kvm/svm/svm.h |  2 +-
>  2 files changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index a713c803a3a3..bff351992468 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -143,6 +143,30 @@ static const struct svm_direct_access_msrs {
>  	{ .index = X2APIC_MSR(APIC_TMICT),		.always = false },
>  	{ .index = X2APIC_MSR(APIC_TMCCT),		.always = false },
>  	{ .index = X2APIC_MSR(APIC_TDCR),		.always = false },
> +	{ .index = MSR_K7_EVNTSEL0,			.always = false },

These are always intercepted, i.e. don't belong in this list.

> +	{ .index = MSR_K7_PERFCTR0,			.always = false },
> +	{ .index = MSR_K7_EVNTSEL1,			.always = false },
> +	{ .index = MSR_K7_PERFCTR1,			.always = false },
> +	{ .index = MSR_K7_EVNTSEL2,			.always = false },
> +	{ .index = MSR_K7_PERFCTR2,			.always = false },
> +	{ .index = MSR_K7_EVNTSEL3,			.always = false },
> +	{ .index = MSR_K7_PERFCTR3,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTL0,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTR0,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTL1,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTR1,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTL2,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTR2,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTL3,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTR3,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTL4,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTR4,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTL5,			.always = false },
> +	{ .index = MSR_F15H_PERF_CTR5,			.always = false },
> +	{ .index = MSR_AMD64_PERF_CNTR_GLOBAL_CTL,	.always = false },
> +	{ .index = MSR_AMD64_PERF_CNTR_GLOBAL_STATUS,	.always = false },
> +	{ .index = MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_CLR,	.always = false },
> +	{ .index = MSR_AMD64_PERF_CNTR_GLOBAL_STATUS_SET,	.always = false },
>  	{ .index = MSR_INVALID,				.always = false },
>  };

As with the Intel patch, this absolutely belongs in the patch that supports
disabling intercepts.

> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 9d7cdb8fbf87..ae71bf5f12d0 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -44,7 +44,7 @@ static inline struct page *__sme_pa_to_page(unsigned long pa)
>  #define	IOPM_SIZE PAGE_SIZE * 3
>  #define	MSRPM_SIZE PAGE_SIZE * 2
>  
> -#define MAX_DIRECT_ACCESS_MSRS	48
> +#define MAX_DIRECT_ACCESS_MSRS	72
>  #define MSRPM_OFFSETS	32
>  extern u32 msrpm_offsets[MSRPM_OFFSETS] __read_mostly;
>  extern bool npt_enabled;
> -- 
> 2.49.0.395.g12beb8f557-goog
>