Commit a02a60b7 authored by Like Xu's avatar Like Xu Committed by Zheng Zengkai
Browse files

perf/x86: Avoid touching LBR_TOS MSR for Arch LBR



stable inclusion
from stable-5.10.40
commit 075becedce372422239a39488adddcb9f6334d50
bugzilla: 51882
CVE: NA

--------------------------------

[ Upstream commit 3317c26a ]

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: 47125db2 ("perf/x86/intel/lbr: Support Architectural LBR")
Signed-off-by: default avatarLike Xu <like.xu@linux.intel.com>
[peterz: simpler still]
Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210430052247.3079672-1-like.xu@linux.intel.com


Signed-off-by: default avatarSasha Levin <sashal@kernel.org>

Signed-off-by: default avatarChen Jun <chenjun102@huawei.com>
Acked-by: default avatarWeilong Chen <chenweilong@huawei.com>
Signed-off-by: default avatarZheng Zengkai <zhengzengkai@huawei.com>
parent 89924edd
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