4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Ganapatrao Kulkarni <ganapatrao.kulkarni@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
[will: added comment to justify the behaviour of exclude_hv]
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm64/kernel/perf_event.c | 23 ++++++++++++++++-------
1 file changed, 16 insertions(+), 7 deletions(-)
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -871,15 +871,24 @@ static int armv8pmu_set_event_filter(str
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