On Thu, Apr 20, 2017 at 02:56:50PM +0530, Ganapatrao Kulkarni wrote: > On Thu, Apr 20, 2017 at 2:19 PM, Mark Rutland <mark.rutl...@arm.com> wrote: > > On Wed, Apr 19, 2017 at 11:14:06PM +0530, Ganapatrao Kulkarni wrote: > >> commit d98ecda (arm64: perf: Count EL2 events if the kernel is running in > >> HYP) > >> is returning error for perf syscall with mixed attribute set for > >> exclude_kernel > >> and exclude_hv. This change is breaking some applications (observed with > >> hhvm) > >> when ran on VHE enabled platforms. > >> > >> Adding fix to consider only exclude_kernel attribute when kernel is > >> running in HYP. Also adding sysfs file to notify the bhehaviour > >> of attribute exclude_hv. > >> > >> Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulka...@cavium.com> > >> --- > >> > >> Changelog: > >> > >> V2: > >> - Changes as per Will Deacon's suggestion. > >> > >> V1: Initial patch > >> > >> arch/arm64/kernel/perf_event.c | 28 ++++++++++++++++++++++++---- > >> include/linux/perf/arm_pmu.h | 1 + > >> 2 files changed, 25 insertions(+), 4 deletions(-) > >> > >> @@ -871,14 +890,13 @@ static int armv8pmu_set_event_filter(struct > >> hw_perf_event *event, > >> > >> if (attr->exclude_idle) > >> return -EPERM; > >> - if (is_kernel_in_hyp_mode() && > >> - attr->exclude_kernel != attr->exclude_hv) > >> - return -EINVAL; > >> + if (is_kernel_in_hyp_mode() && !attr->exclude_kernel) > >> + config_base |= ARMV8_PMU_INCLUDE_EL2; > >> if (attr->exclude_user) > >> config_base |= ARMV8_PMU_EXCLUDE_EL0; > >> if (!is_kernel_in_hyp_mode() && attr->exclude_kernel) > >> config_base |= ARMV8_PMU_EXCLUDE_EL1; > >> - if (!attr->exclude_hv) > >> + if (!is_kernel_in_hyp_mode() && !attr->exclude_hv) > >> config_base |= ARMV8_PMU_INCLUDE_EL2; > > > > This isn't quite what Will suggested. > > > > The idea was that userspace would read sysfs, then use that to determine > > the correct exclusion parameters [1,2]. This logic was not expected to > > change; it correctly validates whether we can provide what the user > > requests. > > OK, if you are ok with sysfs part, i can send next version with that > change only?.
I think the sysfs part is still a little dodgy, since you still expose the "exclude_hv" file with a value of 0 when not running at EL2, which would imply that exclude_hv is forced to zero. I don't think that's correct. Will