Hi Andrew,
On 15/11/2018 12:55, Andrew Murray wrote:
When using VHE, EL1 is unused by the host and EL2 is unused by the
guest - therefore we can filter out these events with the PMU as per
the 'exclude_host' and 'exclude_guest' attributes.
With both VHE and non-VHE we switch the counters between host/guest
at EL2. With non-VHE when using 'exclude_host' we filter out EL2.
These changes eliminate counters counting host events on the
boundaries of guest entry/exit when using :G. However when using :H
unless exclude_hv is set on non-VHE then there is a small blackout
window at the guest entry/exit where host events are not captured.
Signed-off-by: Andrew Murray <andrew.murray@xxxxxxx>
---
arch/arm64/kernel/perf_event.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 89d444f..c079c1f 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -971,12 +971,14 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
* with other architectures (x86 and Power).
*/
if (is_kernel_in_hyp_mode()) {
- if (!attr->exclude_kernel)
+ if (!attr->exclude_kernel && !attr->exclude_host)
config_base |= ARMV8_PMU_INCLUDE_EL2;
+ if (attr->exclude_guest)
+ config_base |= ARMV8_PMU_EXCLUDE_EL1;
Do we really need this ? exclude_guest also implies you need to
exclude guest EL0. We anyway disable the events when we enter the
guest. So the above is not necessary and could possibly create
confusion.
} else {
if (attr->exclude_kernel)
config_base |= ARMV8_PMU_EXCLUDE_EL1;
- if (!attr->exclude_hv)
+ if (!attr->exclude_hv && !attr->exclude_host)
config_base |= ARMV8_PMU_INCLUDE_EL2;
}
if (attr->exclude_user)
I think this can be folded into the previous patch, which adds the
support for exclude_host/guest support. :G, :H are nothing but
the those exclude_ flags.
Otherwise looks good to me.
Cheers
Suzuki
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