linux-kernel - [PATCH v3] arm64: perf: Ignore exclude

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Message-Id: <1493742574-25955-1-git-send-email-ganapatrao.kulkarni@cavium.com>
Date:   Tue,  2 May 2017 21:59:34 +0530
From:   Ganapatrao Kulkarni <ganapatrao.kulkarni@...ium.com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Will.Deacon@....com, catalin.marinas@....com, mark.rutland@....com,
        acme@...nel.org, alexander.shishkin@...ux.intel.com,
        peterz@...radead.org, mingo@...hat.com, jnair@...iumnetworks.com,
        gpkulkarni@...il.com
Subject: [PATCH v3] arm64: perf: Ignore exclude_hv when kernel is running in HYP

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@...ium.com>
---

Changelog:

V2/V3:
 - Changes as per Will Deacon's suggestions.

V1: Initial patch

 arch/arm64/kernel/perf_event.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kernel/perf_event.c b/arch/arm64/kernel/perf_event.c
index 57ae9d9..f6748c0 100644
--- a/arch/arm64/kernel/perf_event.c
+++ b/arch/arm64/kernel/perf_event.c
@@ -871,15 +871,17 @@ static int armv8pmu_set_event_filter(struct hw_perf_event *event,
 
 	if (attr->exclude_idle)
 		return -EPERM;
-	if (is_kernel_in_hyp_mode() &&
-	    attr->exclude_kernel != attr->exclude_hv)
-		return -EINVAL;
+	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
-- 
1.8.1.4