linux-kernel - [PATCH 11/17] KVM: arm64: Use physical PMSELR for PMXEVTYPER if partitioned

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Message-ID: <20250602192702.2125115-12-coltonlewis@google.com>
Date: Mon,  2 Jun 2025 19:26:56 +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 11/17] 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to use the virtual PMSELR register when it could be outdated and lead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 32c003a7b810..8eee8cb218ea 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 afd06400429a..377fa7867152 100644
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -1061,14 +1061,19 @@ static void 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);
-- 
2.49.0.1204.g71687c7c1d-goog