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KVM: vmx/pmu: Release guest LBR event via lazy release mechanism 

The vPMU uses GUEST_LBR_IN_USE_IDX (bit 58) in 'pmu->pmc_in_use' to
indicate whether a guest LBR event is still needed by the vcpu. If the
vcpu no longer accesses LBR related registers within a scheduling time
slice, and the enable bit of LBR has been unset, vPMU will treat the
guest LBR event as a bland event of a vPMC counter and release it
as usual. Also, the pass-through state of LBR records msrs is cancelled.

Signed-off-by: Like Xu <like.xu@linux.intel.com>
Message-Id: <20210201051039.255478-10-like.xu@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Like Xu 2021-02-01 13:10:37 +08:00 committed by Paolo Bonzini
parent e6209a3bef
commit 9aa4f62246
3 changed files with 24 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/x86/kvm/pmu.c
View File

@ -476,6 +476,9 @@ void kvm_pmu_cleanup(struct kvm_vcpu *vcpu)
pmc_stop_counter(pmc);
}
if (kvm_x86_ops.pmu_ops->cleanup)
kvm_x86_ops.pmu_ops->cleanup(vcpu);
bitmap_zero(pmu->pmc_in_use, X86_PMC_IDX_MAX);
}

1
arch/x86/kvm/pmu.h
View File

@ -40,6 +40,7 @@ struct kvm_pmu_ops {
void (*init)(struct kvm_vcpu *vcpu);
void (*reset)(struct kvm_vcpu *vcpu);
void (*deliver_pmi)(struct kvm_vcpu *vcpu);
void (*cleanup)(struct kvm_vcpu *vcpu);
};
static inline u64 pmc_bitmask(struct kvm_pmc *pmc)

21
arch/x86/kvm/vmx/pmu_intel.c
View File

@ -288,8 +288,10 @@ int intel_pmu_create_guest_lbr_event(struct kvm_vcpu *vcpu)
PERF_SAMPLE_BRANCH_USER,
};
if (unlikely(lbr_desc->event))
if (unlikely(lbr_desc->event)) {
__set_bit(INTEL_PMC_IDX_FIXED_VLBR, pmu->pmc_in_use);
return 0;
}
event = perf_event_create_kernel_counter(&attr, -1,
current, NULL, NULL);
@ -300,6 +302,7 @@ int intel_pmu_create_guest_lbr_event(struct kvm_vcpu *vcpu)
}
lbr_desc->event = event;
pmu->event_count++;
__set_bit(INTEL_PMC_IDX_FIXED_VLBR, pmu->pmc_in_use);
return 0;
}
@ -332,9 +335,11 @@ static bool intel_pmu_handle_lbr_msrs_access(struct kvm_vcpu *vcpu,
rdmsrl(index, msr_info->data);
else
wrmsrl(index, msr_info->data);
__set_bit(INTEL_PMC_IDX_FIXED_VLBR, vcpu_to_pmu(vcpu)->pmc_in_use);
local_irq_enable();
return true;
}
clear_bit(INTEL_PMC_IDX_FIXED_VLBR, vcpu_to_pmu(vcpu)->pmc_in_use);
local_irq_enable();
dummy:
@ -532,6 +537,9 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
x86_perf_get_lbr(&lbr_desc->records);
else
lbr_desc->records.nr = 0;
if (lbr_desc->records.nr)
bitmap_set(pmu->all_valid_pmc_idx, INTEL_PMC_IDX_FIXED_VLBR, 1);
}
static void intel_pmu_init(struct kvm_vcpu *vcpu)
@ -665,17 +673,21 @@ static inline void vmx_enable_lbr_msrs_passthrough(struct kvm_vcpu *vcpu)
*/
void vmx_passthrough_lbr_msrs(struct kvm_vcpu *vcpu)
{
struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
struct lbr_desc *lbr_desc = vcpu_to_lbr_desc(vcpu);
if (!lbr_desc->event) {
vmx_disable_lbr_msrs_passthrough(vcpu);
if (vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR)
goto warn;
if (test_bit(INTEL_PMC_IDX_FIXED_VLBR, pmu->pmc_in_use))
goto warn;
return;
}
if (lbr_desc->event->state < PERF_EVENT_STATE_ACTIVE) {
vmx_disable_lbr_msrs_passthrough(vcpu);
__clear_bit(INTEL_PMC_IDX_FIXED_VLBR, pmu->pmc_in_use);
goto warn;
} else
vmx_enable_lbr_msrs_passthrough(vcpu);
@ -687,6 +699,12 @@ warn:
vcpu->vcpu_id);
}
static void intel_pmu_cleanup(struct kvm_vcpu *vcpu)
{
if (!(vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR))
intel_pmu_release_guest_lbr_event(vcpu);
}
struct kvm_pmu_ops intel_pmu_ops = {
.find_arch_event = intel_find_arch_event,
.find_fixed_event = intel_find_fixed_event,
@ -702,4 +720,5 @@ struct kvm_pmu_ops intel_pmu_ops = {
.init = intel_pmu_init,
.reset = intel_pmu_reset,
.deliver_pmi = intel_pmu_deliver_pmi,
.cleanup = intel_pmu_cleanup,
};