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[v4,2/6] target/arm/kvm: Do not silently remove PMU

Message ID 20240720-pmu-v4-2-2a2b28f6b08f@daynix.com
State New
Headers show
Series target/arm/kvm: Report PMU unavailability | expand

Commit Message

Akihiko Odaki July 20, 2024, 9:30 a.m. UTC 
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(-)
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Patch

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());