linux-kernel - [PATCH v2 13/23] KVM: arm64: Use physical PMSELR for PMXEVTYPER if partitioned

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Message-ID: <20250620221326.1261128-15-coltonlewis@google.com>
Date: Fri, 20 Jun 2025 22:13:14 +0000
From: Colton Lewis <coltonlewis@...gle.com>
To: kvm@...r.kernel.org
Cc: Paolo Bonzini <pbonzini@...hat.com>, Jonathan Corbet <corbet@....net>, 
	Russell King <linux@...linux.org.uk>, Catalin Marinas <catalin.marinas@....com>, 
	Will Deacon <will@...nel.org>, Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Joey Gouly <joey.gouly@....com>, Suzuki K Poulose <suzuki.poulose@....com>, 
	Zenghui Yu <yuzenghui@...wei.com>, Mark Rutland <mark.rutland@....com>, 
	Shuah Khan <shuah@...nel.org>, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.linux.dev, 
	linux-perf-users@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	Colton Lewis <coltonlewis@...gle.com>
Subject: [PATCH v2 13/23] KVM: arm64: Use physical PMSELR for PMXEVTYPER if partitioned

Because PMXEVTYPER is trapped and PMSELR is not, it is not appropriate
to use the virtual PMSELR register when it could be outdated and lead
to an invalid write. Use the physical register.

Signed-off-by: Colton Lewis <coltonlewis@...gle.com>
---
 arch/arm64/include/asm/arm_pmuv3.h | 7 ++++++-
 arch/arm64/kvm/sys_regs.c          | 9 +++++++--
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/arm_pmuv3.h b/arch/arm64/include/asm/arm_pmuv3.h
index e2057365ba73..1880e426a559 100644
--- a/arch/arm64/include/asm/arm_pmuv3.h
+++ b/arch/arm64/include/asm/arm_pmuv3.h
@@ -72,11 +72,16 @@ static inline u64 read_pmcr(void)
 	return read_sysreg(pmcr_el0);
 }
 
-static inline void write_pmselr(u32 val)
+static inline void write_pmselr(u64 val)
 {
 	write_sysreg(val, pmselr_el0);
 }
 
+static inline u64 read_pmselr(void)
+{
+	return read_sysreg(pmselr_el0);
+}
+
 static inline void write_pmccntr(u64 val)
 {
 	write_sysreg(val, pmccntr_el0);
diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index 3733e3ce8f39..3140d90849c1 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1066,14 +1066,19 @@ static bool writethrough_pmevtyper(struct kvm_vcpu *vcpu, struct sys_reg_params
 static bool access_pmu_evtyper(struct kvm_vcpu *vcpu, struct sys_reg_params *p,
 			       const struct sys_reg_desc *r)
 {
-	u64 idx, reg;
+	u64 idx, reg, pmselr;
 
 	if (pmu_access_el0_disabled(vcpu))
 		return false;
 
 	if (r->CRn == 9 && r->CRm == 13 && r->Op2 == 1) {
 		/* PMXEVTYPER_EL0 */
-		idx = SYS_FIELD_GET(PMSELR_EL0, SEL, __vcpu_sys_reg(vcpu, PMSELR_EL0));
+		if (kvm_vcpu_pmu_is_partitioned(vcpu))
+			pmselr = read_pmselr();
+		else
+			pmselr = __vcpu_sys_reg(vcpu, PMSELR_EL0);
+
+		idx = SYS_FIELD_GET(PMSELR_EL0, SEL, pmselr);
 		reg = PMEVTYPER0_EL0 + idx;
 	} else if (r->CRn == 14 && (r->CRm & 12) == 12) {
 		idx = ((r->CRm & 3) << 3) | (r->Op2 & 7);
-- 
2.50.0.714.g196bf9f422-goog