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Like XuPeter Zijlstra
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perf/x86/amd: Don't touch the AMD64_EVENTSEL_HOSTONLY bit inside the guest
If we use "perf record" in an AMD Milan guest, dmesg reports a #GP warning from an unchecked MSR access error on MSR_F15H_PERF_CTLx: [] unchecked MSR access error: WRMSR to 0xc0010200 (tried to write 0x0000020000110076) at rIP: 0xffffffff8106ddb4 (native_write_msr+0x4/0x20) [] Call Trace: [] amd_pmu_disable_event+0x22/0x90 [] x86_pmu_stop+0x4c/0xa0 [] x86_pmu_del+0x3a/0x140 The AMD64_EVENTSEL_HOSTONLY bit is defined and used on the host, while the guest perf driver should avoid such use. Fixes: 1018faa ("perf/x86/kvm: Fix Host-Only/Guest-Only counting with SVM disabled") Signed-off-by: Like Xu <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Reviewed-by: Liam Merwick <[email protected]> Tested-by: Kim Phillips <[email protected]> Tested-by: Liam Merwick <[email protected]> Link: https://lkml.kernel.org/r/[email protected]
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arch/x86/events/perf_event.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1115,9 +1115,10 @@ void x86_pmu_stop(struct perf_event *event, int flags);
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static inline void x86_pmu_disable_event(struct perf_event *event)
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{
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u64 disable_mask = __this_cpu_read(cpu_hw_events.perf_ctr_virt_mask);
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struct hw_perf_event *hwc = &event->hw;
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wrmsrl(hwc->config_base, hwc->config);
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wrmsrl(hwc->config_base, hwc->config & ~disable_mask);
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if (is_counter_pair(hwc))
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wrmsrl(x86_pmu_config_addr(hwc->idx + 1), 0);

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