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| author | Like Xu <like.xu@linux.intel.com> | 2021-04-30 07:22:46 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-05-18 12:53:47 +0200 |
| commit | 3317c26a4b413b41364f2c4b83c778c6aba1576d (patch) | |
| tree | 0a52f5b6a64de2ed5b453505e9217f3ece67ab9f /arch | |
| parent | Linux 5.13-rc2 (diff) | |
| download | linux-3317c26a4b413b41364f2c4b83c778c6aba1576d.tar.xz linux-3317c26a4b413b41364f2c4b83c778c6aba1576d.zip | |
perf/x86: Avoid touching LBR_TOS MSR for Arch LBR
The Architecture LBR does not have MSR_LBR_TOS (0x000001c9).
In a guest that should support Architecture LBR, check_msr()
will be a non-related check for the architecture MSR 0x0
(IA32_P5_MC_ADDR) that is also not supported by KVM.
The failure will cause x86_pmu.lbr_nr = 0, thereby preventing
the initialization of the guest Arch LBR. Fix it by avoiding
this extraneous check in intel_pmu_init() for Arch LBR.
Fixes: 47125db27e47 ("perf/x86/intel/lbr: Support Architectural LBR")
Signed-off-by: Like Xu <like.xu@linux.intel.com>
[peterz: simpler still]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210430052247.3079672-1-like.xu@linux.intel.com
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/events/intel/core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 2521d03de5e0..e28892270c58 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -6253,7 +6253,7 @@ __init int intel_pmu_init(void) * Check all LBT MSR here. * Disable LBR access if any LBR MSRs can not be accessed. */ - if (x86_pmu.lbr_nr && !check_msr(x86_pmu.lbr_tos, 0x3UL)) + if (x86_pmu.lbr_tos && !check_msr(x86_pmu.lbr_tos, 0x3UL)) x86_pmu.lbr_nr = 0; for (i = 0; i < x86_pmu.lbr_nr; i++) { if (!(check_msr(x86_pmu.lbr_from + i, 0xffffUL) && |