Messages in this thread Patch in this message | | | From | "Vaden, Tom (HPE Server OS Architecture)" <> | Subject | Re: [PATCH] perf/x86/intel: Disable check_msr for real hw | Date | Sun, 16 Jun 2019 20:56:19 +0000 |
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On 6/16/19 10:13 AM, Jiri Olsa wrote: > On Fri, Jun 14, 2019 at 09:45:21AM -0400, Liang, Kan wrote: >> >> >> On 6/14/2019 7:28 AM, Jiri Olsa wrote: >>> hi, >>> the HPE server can do POST tracing and have enabled LBR >>> tracing during the boot, which makes check_msr fail falsly. >>> >>> It looks like check_msr code was added only to check on guests >>> MSR access, would it be then ok to disable check_msr for real >>> hardware? (as in patch below) >> >> Yes, the check_msr patch was to fix a bug report in guest. >> I didn't get similar bug report for real hardware. >> I think it should be OK to disable it for real hardware. >> > > thanks for confirmation, attaching the full patch > > thanks, > jirka > > > --- > Tom Vaden reported false failure of check_msr function, because > some servers can do POST tracing and enable LBR tracing during > the boot. > > Kan confirmed that check_msr patch was to fix a bug report in > guest, so it's ok to disable it for real HW. > > Cc: Kan Liang <kan.liang@intel.com> > Reported-by: Tom Vaden <tom.vaden@hpe.com> > Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Thanks for handling the patch.
Acked-by: Tom Vaden <tom.vaden@hpe.com>
> --- > arch/x86/events/intel/core.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c > index 71001f005bfe..1194ae7e1992 100644 > --- a/arch/x86/events/intel/core.c > +++ b/arch/x86/events/intel/core.c > @@ -20,6 +20,7 @@ > #include <asm/intel-family.h> > #include <asm/apic.h> > #include <asm/cpu_device_id.h> > +#include <asm/hypervisor.h> > > #include "../perf_event.h" > > @@ -4050,6 +4051,13 @@ static bool check_msr(unsigned long msr, u64 mask) > { > u64 val_old, val_new, val_tmp; > > + /* > + * Disable the check for real HW, so we don't > + * mess up with potentionaly enabled regs. > + */ > + if (hypervisor_is_type(X86_HYPER_NATIVE)) > + return true; > + > /* > * Read the current value, change it and read it back to see if it > * matches, this is needed to detect certain hardware emulators >
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