linux-kernel - [PATCH v2 15/18] perf: arm_spe: Handle guest/host exclusion flags

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Message-Id: <20191220143025.33853-16-andrew.murray@arm.com>
Date:   Fri, 20 Dec 2019 14:30:22 +0000
From:   Andrew Murray <andrew.murray@....com>
To:     Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>
Cc:     Sudeep Holla <sudeep.holla@....com>, kvmarm@...ts.cs.columbia.edu,
        linux-arm-kernel@...ts.infradead.org, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Mark Rutland <mark.rutland@....com>
Subject: [PATCH v2 15/18] perf: arm_spe: Handle guest/host exclusion flags

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.

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 <andrew.murray@....com>
---
 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