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Message-ID: <Yuvgv4QC3oKPlKs2@google.com>
Date: Thu, 4 Aug 2022 15:07:43 +0000
From: Sean Christopherson <seanjc@...gle.com>
To: Like Xu <like.xu.linux@...il.com>
Cc: Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>
Subject: Re: [PATCH v2 2/7] perf/x86/core: Remove unnecessary stubs provided
for KVM-only helpers
On Thu, Aug 04, 2022, Like Xu wrote:
> On 4/8/2022 3:26 am, Sean Christopherson wrote:
> > -#if defined(CONFIG_PERF_EVENTS) && defined(CONFIG_CPU_SUP_AMD)
> > - extern void amd_pmu_enable_virt(void);
> > - extern void amd_pmu_disable_virt(void);
> > -
> > -#if defined(CONFIG_PERF_EVENTS_AMD_BRS)
> > +#ifdef CONFIG_PERF_EVENTS_AMD_BRS
> > #define PERF_NEEDS_LOPWR_CB 1
> > @@ -566,12 +538,13 @@ static inline void perf_lopwr_cb(bool lopwr_in)
> > static_call_mod(perf_lopwr_cb)(lopwr_in);
> > }
> > -#endif /* PERF_NEEDS_LOPWR_CB */
>
> Oops, now the definition of PERF_NEEDS_LOPWR_CB will not be unset.
> This is not mentioned in the commit message and may cause trouble.
PERF_NEEDS_LOPWR_CB isn't being "unset" in the existing code, the comment is simply
wrong. The #endif pairs with CONFIG_PERF_EVENTS_AMD_BRS.
#if defined(CONFIG_PERF_EVENTS_AMD_BRS)
#define PERF_NEEDS_LOPWR_CB 1
/*
* architectural low power callback impacts
* drivers/acpi/processor_idle.c
* drivers/acpi/acpi_pad.c
*/
extern void perf_amd_brs_lopwr_cb(bool lopwr_in);
DECLARE_STATIC_CALL(perf_lopwr_cb, perf_amd_brs_lopwr_cb);
static inline void perf_lopwr_cb(bool lopwr_in)
{
static_call_mod(perf_lopwr_cb)(lopwr_in);
}
#endif /* PERF_NEEDS_LOPWR_CB */ <=== should be /* CONFIG_PERF_EVENTS_AMD_BRS */
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