2019-07-25 05:53:41

by Zhenzhong Duan

Subject: [PATCH] perf/x86: Apply more accurate check on hypervisor platform

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 <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
---
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

2019-07-25 12:38:04

by Peter Zijlstra

Subject: Re: [PATCH] perf/x86: Apply more accurate check on hypervisor platform

On Thu, Jul 25, 2019 at 10:39:26AM +0800, Zhenzhong Duan wrote:
> 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 <[email protected]>
> Cc: Peter Zijlstra <[email protected]>
> Cc: Arnaldo Carvalho de Melo <[email protected]>
> Cc: Alexander Shishkin <[email protected]>
> Cc: Jiri Olsa <[email protected]>
> Cc: Namhyung Kim <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: Borislav Petkov <[email protected]>
> Cc: Juergen Gross <[email protected]>
> Cc: Boris Ostrovsky <[email protected]>

Thanks!

2019-07-25 18:06:16

by tip-bot for Vasyl Gomonovych

Subject: [tip:perf/urgent] perf/x86: Apply more accurate check on hypervisor platform

Commit-ID: 5ea3f6fb37b79da33ac9211df336fd2b9f47c39f
Gitweb: https://git.kernel.org/tip/5ea3f6fb37b79da33ac9211df336fd2b9f47c39f
Author: Zhenzhong Duan <[email protected]>
AuthorDate: Thu, 25 Jul 2019 10:39:26 +0800
Committer: Ingo Molnar <[email protected]>
CommitDate: Thu, 25 Jul 2019 15:41:30 +0200

perf/x86: Apply more accurate check on hypervisor platform

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 <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Alexander Shishkin <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Boris Ostrovsky <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Juergen Gross <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
---
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 b35519cbc8b4..c9075fc75cb6 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;

/*