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From: Like Xu <like.xu.linux@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>,
	Joerg Roedel <joerg.roedel@amd.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, "H . Peter Anvin" <hpa@zytor.com>,
	linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2] perf/x86/amd: Don't touch the AMD64_EVENTSEL_HOSTONLY bit inside the guest
Date: Mon,  2 Aug 2021 15:08:50 +0800	[thread overview]
Message-ID: <20210802070850.35295-1-likexu@tencent.com> (raw)

From: Like Xu <likexu@tencent.com>

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: 1018faa6cf23 ("perf/x86/kvm: Fix Host-Only/Guest-Only counting with SVM disabled")
Signed-off-by: Like Xu <likexu@tencent.com>
Tested-by: Kim Phillips <kim.phillips@amd.com>
---
v2: Add Fixes tag and Tested-by from Kim.
v1: https://lore.kernel.org/lkml/20210720112605.63286-1-likexu@tencent.com/

 arch/x86/events/perf_event.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index d6003e08b055..1c3ae954a230 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -1116,8 +1116,9 @@ void x86_pmu_stop(struct perf_event *event, int flags);
 static inline void x86_pmu_disable_event(struct perf_event *event)
 {
 	struct hw_perf_event *hwc = &event->hw;
+	u64 disable_mask = __this_cpu_read(cpu_hw_events.perf_ctr_virt_mask);
 
-	wrmsrl(hwc->config_base, hwc->config);
+	wrmsrl(hwc->config_base, hwc->config & ~disable_mask);
 
 	if (is_counter_pair(hwc))
 		wrmsrl(x86_pmu_config_addr(hwc->idx + 1), 0);
-- 
2.32.0


             reply	other threads:[~2021-08-02  7:09 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-02  7:08 Like Xu [this message]
2021-08-04 11:28 ` [PATCH v2] perf/x86/amd: Don't touch the AMD64_EVENTSEL_HOSTONLY bit inside the guest Liam Merwick
2021-08-04 13:02   ` Peter Zijlstra
2021-08-05  9:34 ` [tip: perf/urgent] " tip-bot2 for Like Xu

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