linux-kernel - [PATCH v2 02/14] drivers/perf: apple_m1: Support host/guest event filtering

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Message-Id: <20250203183111.191519-3-oliver.upton@linux.dev>
Date: Mon,  3 Feb 2025 10:30:59 -0800
From: Oliver Upton <oliver.upton@...ux.dev>
To: kvmarm@...ts.linux.dev
Cc: Marc Zyngier <maz@...nel.org>,
	Joey Gouly <joey.gouly@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	Mingwei Zhang <mizhang@...gle.com>,
	Colton Lewis <coltonlewis@...gle.com>,
	Raghavendra Rao Ananta <rananta@...gle.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	Oliver Upton <oliver.upton@...ux.dev>,
	Janne Grunau <j@...nau.net>
Subject: [PATCH v2 02/14] drivers/perf: apple_m1: Support host/guest event filtering

The PMU appears to have a separate register for filtering 'guest'
exception levels (i.e. EL1 and !ELIsInHost(EL0)) which has the same
layout as PMCR1_EL1. Conveniently, there exists a VHE register alias
(PMCR1_EL12) that can be used to configure it.

Support guest events by programming the EL12 register with the intended
guest kernel/userspace filters. Limit support for guest events to VHE
(i.e. kernel running at EL2), as it avoids involving KVM to context
switch PMU registers. VHE is the only supported mode on M* parts anyway,
so this isn't an actual feature limitation.

Tested-by: Janne Grunau <j@...nau.net>
Signed-off-by: Oliver Upton <oliver.upton@...ux.dev>
---
 drivers/perf/apple_m1_cpu_pmu.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/perf/apple_m1_cpu_pmu.c b/drivers/perf/apple_m1_cpu_pmu.c
index cea80afd1253..d6d4ff6da862 100644
--- a/drivers/perf/apple_m1_cpu_pmu.c
+++ b/drivers/perf/apple_m1_cpu_pmu.c
@@ -120,6 +120,8 @@ enum m1_pmu_events {
 	 */
 	M1_PMU_CFG_COUNT_USER					= BIT(8),
 	M1_PMU_CFG_COUNT_KERNEL					= BIT(9),
+	M1_PMU_CFG_COUNT_HOST					= BIT(10),
+	M1_PMU_CFG_COUNT_GUEST					= BIT(11),
 };
 
 /*
@@ -328,7 +330,7 @@ static void m1_pmu_disable_counter_interrupt(unsigned int index)
 }
 
 static void __m1_pmu_configure_event_filter(unsigned int index, bool user,
-					    bool kernel)
+					    bool kernel, bool host)
 {
 	u64 clear, set, user_bit, kernel_bit;
 
@@ -356,7 +358,10 @@ static void __m1_pmu_configure_event_filter(unsigned int index, bool user,
 	else
 		clear |= kernel_bit;
 
-	sysreg_clear_set_s(SYS_IMP_APL_PMCR1_EL1, clear, set);
+	if (host)
+		sysreg_clear_set_s(SYS_IMP_APL_PMCR1_EL1, clear, set);
+	else if (is_kernel_in_hyp_mode())
+		sysreg_clear_set_s(SYS_IMP_APL_PMCR1_EL12, clear, set);
 }
 
 static void __m1_pmu_configure_eventsel(unsigned int index, u8 event)
@@ -391,10 +396,13 @@ static void __m1_pmu_configure_eventsel(unsigned int index, u8 event)
 static void m1_pmu_configure_counter(unsigned int index, unsigned long config_base)
 {
 	bool kernel = config_base & M1_PMU_CFG_COUNT_KERNEL;
+	bool guest = config_base & M1_PMU_CFG_COUNT_GUEST;
+	bool host = config_base & M1_PMU_CFG_COUNT_HOST;
 	bool user = config_base & M1_PMU_CFG_COUNT_USER;
 	u8 evt = config_base & M1_PMU_CFG_EVENT;
 
-	__m1_pmu_configure_event_filter(index, user, kernel);
+	__m1_pmu_configure_event_filter(index, user && host, kernel && host, true);
+	__m1_pmu_configure_event_filter(index, user && guest, kernel && guest, false);
 	__m1_pmu_configure_eventsel(index, evt);
 }
 
@@ -570,7 +578,7 @@ static int m1_pmu_set_event_filter(struct hw_perf_event *event,
 {
 	unsigned long config_base = 0;
 
-	if (!attr->exclude_guest) {
+	if (!attr->exclude_guest && !is_kernel_in_hyp_mode()) {
 		pr_debug("ARM performance counters do not support mode exclusion\n");
 		return -EOPNOTSUPP;
 	}
@@ -578,6 +586,10 @@ static int m1_pmu_set_event_filter(struct hw_perf_event *event,
 		config_base |= M1_PMU_CFG_COUNT_KERNEL;
 	if (!attr->exclude_user)
 		config_base |= M1_PMU_CFG_COUNT_USER;
+	if (!attr->exclude_host)
+		config_base |= M1_PMU_CFG_COUNT_HOST;
+	if (!attr->exclude_guest)
+		config_base |= M1_PMU_CFG_COUNT_GUEST;
 
 	event->config_base = config_base;
 
-- 
2.39.5