perf/x86/amd/core: Fix overflow reset on hotplug
[ Upstream commit 23d2626b ] Kernels older than v5.19 do not support PerfMonV2 and the PMI handler does not clear the overflow bits of the PerfCntrGlobalStatus register. Because of this, loading a recent kernel using kexec from an older kernel can result in inconsistent register states on Zen 4 systems. The PMI handler of the new kernel gets confused and shows a warning when an overflow occurs because some of the overflow bits are set even if the corresponding counters are inactive. These are remnants from overflows that were handled by the older kernel. During CPU hotplug, the PerfCntrGlobalCtl and PerfCntrGlobalStatus registers should always be cleared for PerfMonV2-capable processors. However, a condition used for NB event constaints applicable only to older processors currently prevents this from happening. Move the reset sequence to an appropriate place and also clear the LBR Freeze bit. Fixes: 21d59e3e ("perf/x86/amd/core: Detect PerfMonV2 support") Signed-off-by:Sandipan Das <sandipan.das@amd.com> Signed-off-by:
Ingo Molnar <mingo@kernel.org> Link: https://lore.kernel.org/r/882a87511af40792ba69bb0e9026f19a2e71e8a3.1694696888.git.sandipan.das@amd.com Signed-off-by:
Sasha Levin <sashal@kernel.org>
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6150d459
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