linux-kernel - [PATCH] perf: qcom_l2_pmu: don't allow guest access

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Message-Id: <1512575733-923-1-git-send-email-nleeder@codeaurora.org>
Date:   Wed,  6 Dec 2017 10:55:33 -0500
From:   Neil Leeder <nleeder@...eaurora.org>
To:     Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Mark Langsdorf <mlangsdo@...hat.com>,
        Mark Salter <msalter@...hat.com>, Jon Masters <jcm@...hat.com>,
        Timur Tabi <timur@...eaurora.org>,
        Mark Brown <broonie@...nel.org>, nleeder@...eaurora.org
Subject: [PATCH] perf: qcom_l2_pmu: don't allow guest access

Guests cannot access IMPDEF system registers, which are used
by this driver. Disable the driver if it's running in a guest VM.

Signed-off-by: Neil Leeder <nleeder@...eaurora.org>
---
 drivers/perf/qcom_l2_pmu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/perf/qcom_l2_pmu.c b/drivers/perf/qcom_l2_pmu.c
index 4fdc848..49dc954 100644
--- a/drivers/perf/qcom_l2_pmu.c
+++ b/drivers/perf/qcom_l2_pmu.c
@@ -1057,6 +1057,10 @@ static int __init register_l2_cache_pmu_driver(void)
 {
 	int err;
 
+	/* Don't enable driver if running as guest */
+	if (!is_hyp_mode_available())
+		return 0;
+
 	err = cpuhp_setup_state_multi(CPUHP_AP_PERF_ARM_QCOM_L2_ONLINE,
 				      "AP_PERF_ARM_QCOM_L2_ONLINE",
 				      l2cache_pmu_online_cpu,
-- 
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.