Re: [PATCH v2 15/18] perf: arm_spe: Handle guest/host exclusion flags
From: Mark Rutland <mark.rutland@arm.com>
Date: 2019-12-20 18:10:05
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On Fri, Dec 20, 2019 at 02:30:22PM +0000, Andrew Murray wrote:
A side effect of supporting the SPE in guests is that we prevent the host from collecting data whilst inside a guest thus creating a black-out window. This occurs because instead of emulating the SPE, we share it with our guests.
We used to permit this; do we know if anyone is using it? Thanks, Mark.
quoted hunk ↗ jump to hunk
Let's accurately describe our capabilities by using the perf exclude flags to prevent !exclude_guest and exclude_host flags from being used. Signed-off-by: Andrew Murray <redacted> --- drivers/perf/arm_spe_pmu.c | 3 +++ 1 file changed, 3 insertions(+)diff --git a/drivers/perf/arm_spe_pmu.c b/drivers/perf/arm_spe_pmu.c index 2d24af4cfcab..3703dbf459de 100644 --- a/drivers/perf/arm_spe_pmu.c +++ b/drivers/perf/arm_spe_pmu.c@@ -679,6 +679,9 @@ static int arm_spe_pmu_event_init(struct perf_event *event) if (attr->exclude_idle) return -EOPNOTSUPP; + if (!attr->exclude_guest || attr->exclude_host) + return -EOPNOTSUPP; + /* * Feedback-directed frequency throttling doesn't work when we * have a buffer of samples. We'd need to manually count the-- 2.21.0
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