From: Ganapatrao Kulkarni ganapatrao.kulkarni@cavium.com
[ Upstream commit 78a19cfdf37d19002c83c8790853c1cc10feccdc ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/arm64/kernel/perf_event.c | 23 ++++++++++++++++------- 1 file changed, 16 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c index 57ae9d9ed9bb..199a23f058d5 100644 --- a/arch/arm64/kernel/perf_event.c +++ b/arch/arm64/kernel/perf_event.c @@ -871,15 +871,24 @@ 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