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From: Zhenzhong Duan <zhenzhong.duan@oracle.com>
To: linux-kernel@vger.kernel.org
Cc: x86@kernel.org, Zhenzhong Duan <zhenzhong.duan@oracle.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Juergen Gross <jgross@suse.com>,
	Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: [PATCH] perf/x86: Apply more accurate check on hypervisor platform
Date: Thu, 25 Jul 2019 10:39:26 +0800	[thread overview]
Message-ID: <1564022366-18293-1-git-send-email-zhenzhong.duan@oracle.com> (raw)

check_msr is used to fix a bug report in guest where KVM doesn't support
LBR MSR and cause #GP.

The msr check is bypassed on real HW to workaround a false failure,
see commit d0e1a507bdc7 ("perf/x86/intel: Disable check_msr for real HW")

When running a guest with CONFIG_HYPERVISOR_GUEST not set or "nopv"
enabled, current check isn't enough and #GP could trigger.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Juergen Gross <jgross@suse.com>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
 arch/x86/events/intel/core.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 9e911a9..86f3656 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -20,7 +20,6 @@
 #include <asm/intel-family.h>
 #include <asm/apic.h>
 #include <asm/cpu_device_id.h>
-#include <asm/hypervisor.h>
 
 #include "../perf_event.h"
 
@@ -4053,7 +4052,7 @@ static bool check_msr(unsigned long msr, u64 mask)
 	 * Disable the check for real HW, so we don't
 	 * mess with potentionaly enabled registers:
 	 */
-	if (hypervisor_is_type(X86_HYPER_NATIVE))
+	if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
 		return true;
 
 	/*
-- 
1.8.3.1


             reply	other threads:[~2019-07-25  2:40 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-25  2:39 Zhenzhong Duan [this message]
2019-07-25  7:46 ` Peter Zijlstra
2019-07-25 16:07 ` [tip:perf/urgent] " tip-bot for Zhenzhong Duan

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