From: Like Xu <like.xu@linux.intel.com>
To: Peter Zijlstra <peterz@infradead.org>,
Kan Liang <kan.liang@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Borislav Petkov <bp@alien8.de>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Like Xu <like.xu@linux.intel.com>
Subject: [PATCH RESEND 1/2] perf/x86: Skip checking MSR for MSR 0x0
Date: Wed, 21 Apr 2021 10:18:24 +0800 [thread overview]
Message-ID: <20210421021825.37872-1-like.xu@linux.intel.com> (raw)
The Architecture LBR does not have MSR_LBR_TOS (0x000001c9).
When ARCH_LBR we don't set lbr_tos, the failure from the
check_msr() against MSR 0x000 will make x86_pmu.lbr_nr = 0,
thereby preventing the initialization of the guest LBR.
Fixes: 47125db27e47 ("perf/x86/intel/lbr: Support Architectural LBR")
Signed-off-by: Like Xu <like.xu@linux.intel.com>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
---
arch/x86/events/intel/core.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 5272f349dca2..5036496caa60 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4751,10 +4751,10 @@ static bool check_msr(unsigned long msr, u64 mask)
u64 val_old, val_new, val_tmp;
/*
- * Disable the check for real HW, so we don't
+ * Disable the check for real HW or non-sense msr, so we don't
* mess with potentionaly enabled registers:
*/
- if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
+ if (!boot_cpu_has(X86_FEATURE_HYPERVISOR) || !msr)
return true;
/*
--
2.30.2
next reply other threads:[~2021-04-21 2:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-21 2:18 Like Xu [this message]
2021-04-21 2:18 ` [PATCH RESEND 2/2] perf/x86/lbr: Move cpuc->lbr_xsave allocation out of sleeping region Like Xu
2021-04-21 8:38 ` Peter Zijlstra
2021-04-21 8:48 ` Like Xu
2021-04-21 9:21 ` Peter Zijlstra
2021-04-21 15:30 ` [PATCH RESEND 1/2] perf/x86: Skip checking MSR for MSR 0x0 Sean Christopherson
2021-04-22 1:18 ` Like Xu
2021-04-22 1:38 ` Sean Christopherson
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