Add internal state for PMUv3 emulation without programmable event
counters. When fixed-counters-only mode is active, KVM reports no
programmable counters and hides PMCEID, avoiding event-counter state
whose behavior can depend on the selected hardware PMU.
The cycle counter still uses a host perf event. Unlike the normal PMU
path, fixed-counters-only mode may create that event from the hardware
PMU attached to the VCPU's current pCPU. If the VCPU later loads on a
pCPU that is not covered by the existing event's PMU, request a PMU
reload so the cycle counter can be recreated against the new pCPU's PMU.
Keep this affinity check limited to fixed-counters-only VMs; the normal
programmable-counter mode continues to use the VM-wide PMU and does not
need per-load reload decisions.
Add a separate internal flag for explicit userspace PMU selection. The
UAPI wiring added later will use it to keep explicit PMU selection and
fixed-counters-only mode mutually exclusive while still allowing
fixed-counters-only mode to replace the default PMU selected during
KVM_ARM_VCPU_INIT.
The UAPI wiring that sets the fixed-counters-only flag and records
explicit PMU selection is added later in the series.
Signed-off-by: Akihiko Odaki <[email protected]>
---
arch/arm64/include/asm/kvm_host.h | 4 ++++
arch/arm64/kvm/arm.c | 1 +
arch/arm64/kvm/pmu-emul.c | 43 +++++++++++++++++++++++++++++++++++++--
include/kvm/arm_pmu.h | 2 ++
4 files changed, 48 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h
b/arch/arm64/include/asm/kvm_host.h
index 0c39d9db7d57..aa07b05b8231 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -353,6 +353,10 @@ struct kvm_arch {
#define KVM_ARCH_FLAG_WRITABLE_IMP_ID_REGS 10
/* Unhandled SEAs are taken to userspace */
#define KVM_ARCH_FLAG_EXIT_SEA 11
+ /* PMUv3 is emulated with an explicitly specified hardware PMU */
+#define KVM_ARCH_FLAG_PMU_V3_EXPLICIT 12
+ /* PMUv3 is emulated without progammable event counters */
+#define KVM_ARCH_FLAG_PMU_V3_FIXED_COUNTERS_ONLY 13
unsigned long flags;
/* VM-wide vCPU feature set */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 68767bb08285..1cc7754d5ace 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -687,6 +687,7 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
if (has_vhe())
kvm_vcpu_load_vhe(vcpu);
kvm_arch_vcpu_load_fp(vcpu);
+ kvm_vcpu_load_pmu(vcpu);
kvm_vcpu_pmu_restore_guest(vcpu);
if (kvm_arm_is_pvtime_enabled(&vcpu->arch))
kvm_make_request(KVM_REQ_RECORD_STEAL, vcpu);
diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index e70628653e4b..40cad183376c 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -96,6 +96,11 @@ u64 kvm_pmu_evtyper_mask(struct kvm *kvm)
return mask;
}
+static bool kvm_pmu_fixed_counters_only(struct kvm *kvm)
+{
+ return test_bit(KVM_ARCH_FLAG_PMU_V3_FIXED_COUNTERS_ONLY,
&kvm->arch.flags);
+}
+
/**
* kvm_pmc_is_64bit - determine if counter is 64bit
* @pmc: counter context
@@ -343,7 +348,11 @@ u64 kvm_pmu_implemented_counter_mask(struct kvm_vcpu *vcpu)
static void kvm_pmc_enable_perf_event(struct kvm_pmc *pmc)
{
- if (!pmc->perf_event) {
+ struct kvm_vcpu *vcpu = kvm_pmc_to_vcpu(pmc);
+
+ if (!pmc->perf_event ||
+ (kvm_pmu_fixed_counters_only(vcpu->kvm) &&
+ !cpumask_test_cpu(vcpu->cpu,
&to_arm_pmu(pmc->perf_event->pmu)->supported_cpus))) {
kvm_pmu_create_perf_event(pmc);
return;
}
@@ -720,6 +729,12 @@ static void kvm_pmu_create_perf_event(struct kvm_pmc *pmc)
int eventsel;
u64 evtreg;
+ if (kvm_pmu_fixed_counters_only(vcpu->kvm)) {
+ arm_pmu = kvm_pmu_probe_armpmu(vcpu->cpu);
+ if (WARN_ON_ONCE(!arm_pmu))
+ return;
+ }
+
evtreg = kvm_pmc_read_evtreg(pmc);
kvm_pmu_stop_counter(pmc);
@@ -748,7 +763,7 @@ static void kvm_pmu_create_perf_event(struct kvm_pmc *pmc)
* Don't create an event if we're running on hardware that requires
* PMUv3 event translation and we couldn't find a valid mapping.
*/
- eventsel = kvm_map_pmu_event(vcpu->kvm->arch.arm_pmu, eventsel);
+ eventsel = kvm_map_pmu_event(arm_pmu, eventsel);
if (eventsel < 0)
return;
@@ -878,6 +893,9 @@ u64 kvm_pmu_get_pmceid(struct kvm_vcpu *vcpu, bool pmceid1)
u64 val, mask = 0;
int base, i, nr_events;
+ if (kvm_pmu_fixed_counters_only(vcpu->kvm))
+ return 0;
+
