perf/x86: fix RAPL rdmsrl_safe() usage
Subsystems (2)
PATCH 1/1 perf/x86: fix RAPL rdmsrl_safe() usage
This patch fixes a bug introduced by commit 24223657.
The rdmsrl_safe() function returns 0 on success. The current code was failing to detect the RAPL PMU on real hardware (missing /sys/devices/power) because the return value of rdmsrl_safe() was misinterpreted.
arch/x86/kernel/cpu/perf_event_intel_rapl.c +2 -1
@@ -543,7 +543,8 @@ static int rapl_cpu_prepare(int cpu)if (phys_id <0 )return -1 ; -if (!rdmsrl_safe (MSR_RAPL_POWER_UNIT , &msr_rapl_power_unit_bits)) +/* protect rdmsrl() to handle virtualization */ +if (rdmsrl_safe (MSR_RAPL_POWER_UNIT , &msr_rapl_power_unit_bits))return -1 ; pmu =kzalloc_node (sizeof (*pmu),GFP_KERNEL ,cpu_to_node (cpu));
Quoted 2 lines · Stephane Eranian
This patch fixes a bug introduced by commit 24223657.
Maybe add
tag?
Quoted 6 lines
The
rdmsrl_safe()function returns 0 on success. The current code was failing to detect the RAPL PMU on real hardware (missing/sys/devices/power) because the return value ofrdmsrl_safe()was misinterpreted.Signed-off-by Stephane Eranian <[email protected]>
Signature · 5 lines
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--Quoted 10 lines · Borislav Petkov
Quoted 2 lines · Stephane Eranian
This patch fixes a bug introduced by commit 24223657.
Maybe add
Fixes <commit-id>tag?
Quoted 8 lines
Quoted 6 lines
The
rdmsrl_safe()function returns 0 on success. The current code was failing to detect the RAPL PMU on real hardware (missing/sys/devices/power) because the return value ofrdmsrl_safe()was misinterpreted.Signed-off-by Stephane Eranian <[email protected]>Acked-by Borislav Petkov <[email protected]>
-- vs;
Quoted 3 lines
Quoted 1 line
Acked-by Borislav Petkov <[email protected]>Brown-Paper-Bag-Worn-By Venkatesh Srinivas <[email protected]>
Again the bug is really in KVM. We wouldn't need all this crap if KVM didn't throw the bogus #GPs. I'm sure you missed plenty of MSR accesses elsewhere, and it's a ticking time bomb.
If the VM lies to the kernel with the family-model you need to at least limit the consequences. KVM is spectacularly failing to do that by throwing bogus #GPs.
The brown paper bad needs to be employed on the KVM code (or better the bug be fixed there, by defaulting to not #GP on unknown MSRs)
-Andi
Signature · 1 line
[email protected] -- Speaking for myself only
tip-bot for Stephane Eranian
merge bot[tip:perf/urgent] perf/x86: Fix RAPL rdmsrl_safe() usage
In reply to Stephane Eranianperf/x86: Fix RAPL rdmsrl_safe() usage
Commit-ID: 9f7ff8931e3c5ddc8535476971ec9501e9555c05 Gitweb: http://git.kernel.org/tip/9f7ff8931e3c5ddc8535476971ec9501e9555c05 Author: Stephane Eranian <[email protected]> AuthorDate: Wed, 23 Apr 2014 19:04:19 +0200 Committer: Ingo Molnar <[email protected]> CommitDate: Thu, 24 Apr 2014 08:12:41 +0200
perf/x86: Fix RAPL rdmsrl_safe() usage
This patch fixes a bug introduced by:
24223657806a ("perf/x86/intel: Use rdmsrl_safe() when initializing RAPL PMU")
The rdmsrl_safe() function returns 0 on success. The current code was failing to detect the RAPL PMU on real hardware (missing /sys/devices/power) because the return value of rdmsrl_safe() was misinterpreted.
--- arch/x86/kernel/cpu/perf_event_intel_rapl.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
arch/x86/kernel/cpu/perf_event_intel_rapl.c +2 -1
@@ -543,7 +543,8 @@ static int rapl_cpu_prepare(int cpu)if (phys_id <0 )return -1 ; -if (!rdmsrl_safe (MSR_RAPL_POWER_UNIT , &msr_rapl_power_unit_bits)) +/* protect rdmsrl() to handle virtualization */ +if (rdmsrl_safe (MSR_RAPL_POWER_UNIT , &msr_rapl_power_unit_bits))return -1 ; pmu =kzalloc_node (sizeof (*pmu),GFP_KERNEL ,cpu_to_node (cpu));