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| author | Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com> | 2017-05-02 21:59:34 +0530 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2017-05-15 18:30:37 +0100 |
| commit | 78a19cfdf37d19002c83c8790853c1cc10feccdc (patch) | |
| tree | 6e38f50adf729eac3552bba63eae030b0b07cb97 /arch/arm64/kernel/perf_event.c | |
| parent | 8df728e1ae614f592961e51f65d3e3212ede5a75 (diff) | |
| download | lwn-78a19cfdf37d19002c83c8790853c1cc10feccdc.tar.gz lwn-78a19cfdf37d19002c83c8790853c1cc10feccdc.zip | |
arm64: perf: Ignore exclude_hv when kernel is running in HYP
commit d98ecdaca296 ("arm64: perf: Count EL2 events if the kernel is
running in HYP") returns -EINVAL when perf system call perf_event_open is
called with exclude_hv != exclude_kernel. This change breaks applications
on VHE enabled ARMv8.1 platforms. The issue was observed with HHVM
application, which calls perf_event_open with exclude_hv = 1 and
exclude_kernel = 0.
There is no separate hypervisor privilege level when VHE is enabled, the
host kernel runs at EL2. So when VHE is enabled, we should ignore
exclude_hv from the application. This behaviour is consistent with PowerPC
where the exclude_hv is ignored when the hypervisor is not present and with
x86 where this flag is ignored.
Signed-off-by: Ganapatrao Kulkarni <ganapatrao.kulkarni@cavium.com>
[will: added comment to justify the behaviour of exclude_hv]
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/perf_event.c')
| -rw-r--r-- | arch/arm64/kernel/perf_event.c | 23 |
1 files changed, 16 insertions, 7 deletions
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index bcc79471b38e..83a1b1ad189f 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -877,15 +877,24 @@ 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 we're running in hyp mode, then we *are* the hypervisor. + * Therefore we ignore exclude_hv in this configuration, since + * there's no hypervisor to sample anyway. This is consistent + * with other architectures (x86 and Power). + */ + if (is_kernel_in_hyp_mode()) { + if (!attr->exclude_kernel) + config_base |= ARMV8_PMU_INCLUDE_EL2; + } else { + if (attr->exclude_kernel) + config_base |= ARMV8_PMU_EXCLUDE_EL1; + if (!attr->exclude_hv) + 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) - config_base |= ARMV8_PMU_INCLUDE_EL2; /* * Install the filter into config_base as this is used to |