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From: Akihiko Odaki <akihiko.odaki@daynix.com>
To: Peter Maydell <peter.maydell@linaro.org>,
	 Thomas Huth <thuth@redhat.com>,
	Laurent Vivier <lvivier@redhat.com>,
	 Paolo Bonzini <pbonzini@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>
Cc: qemu-arm@nongnu.org, qemu-devel@nongnu.org, kvm@vger.kernel.org,
	 Akihiko Odaki <akihiko.odaki@daynix.com>
Subject: [PATCH v4 2/6] target/arm/kvm: Do not silently remove PMU
Date: Sat, 20 Jul 2024 18:30:50 +0900	[thread overview]
Message-ID: <20240720-pmu-v4-2-2a2b28f6b08f@daynix.com> (raw)
In-Reply-To: <20240720-pmu-v4-0-2a2b28f6b08f@daynix.com>

kvm_arch_init_vcpu() used to remove PMU when it is not available even
if the CPU model needs one. It is semantically incorrect, and may
continue execution on a misbehaving host that advertises a CPU model
while lacking its PMU. Keep the PMU when the CPU model needs one, and
let kvm_arm_vcpu_init() fail if the KVM implementation mismatches with
our expectation.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
---
 target/arm/kvm.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index b20a35052f41..849e2e21b304 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -1888,13 +1888,8 @@ int kvm_arch_init_vcpu(CPUState *cs)
     if (!arm_feature(env, ARM_FEATURE_AARCH64)) {
         cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_EL1_32BIT;
     }
-    if (!kvm_check_extension(cs->kvm_state, KVM_CAP_ARM_PMU_V3)) {
-        cpu->has_pmu = false;
-    }
     if (cpu->has_pmu) {
         cpu->kvm_init_features[0] |= 1 << KVM_ARM_VCPU_PMU_V3;
-    } else {
-        env->features &= ~(1ULL << ARM_FEATURE_PMU);
     }
     if (cpu_isar_feature(aa64_sve, cpu)) {
         assert(kvm_arm_sve_supported());

-- 
2.45.2



  parent reply	other threads:[~2024-07-20  9:32 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-07-20  9:30 [PATCH v4 0/6] target/arm/kvm: Report PMU unavailability Akihiko Odaki
2024-07-20  9:30 ` [PATCH v4 1/6] target/arm/kvm: Set PMU for host only when available Akihiko Odaki
2024-07-20  9:30 ` Akihiko Odaki [this message]
2024-07-20  9:30 ` [PATCH v4 3/6] target/arm: Always add pmu property for Armv7-A/R+ Akihiko Odaki
2024-07-29 15:13   ` Peter Maydell
2024-07-29 16:32     ` Akihiko Odaki
2024-07-20  9:30 ` [PATCH v4 4/6] hvf: arm: Raise an exception for sysreg by default Akihiko Odaki
2024-07-20  9:30 ` [PATCH v4 5/6] hvf: arm: Properly disable PMU Akihiko Odaki
2024-07-20  9:30 ` [PATCH v4 6/6] hvf: arm: Do not advance PC when raising an exception Akihiko Odaki
2024-08-02  6:41   ` Michael Tokarev
2024-08-02  6:44     ` Akihiko Odaki
2024-08-02  7:32       ` Michael Tokarev
2024-07-29 15:15 ` [PATCH v4 0/6] target/arm/kvm: Report PMU unavailability Peter Maydell

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