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arm64: perf: Ignore exclude_hv when kernel is running in HYP

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commit d98ecdaca2 ("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>
This commit is contained in:
Ganapatrao Kulkarni 2017-05-02 21:59:34 +05:30 committed by Catalin Marinas
parent 8df728e1ae
commit 78a19cfdf3
1 changed files with 16 additions and 7 deletions
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23
arch/arm64/kernel/perf_event.c
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@ -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