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Subject[PATCH RESEND v3 03/11] KVM: x86/pmu: Protect kvm->arch.pmu_event_filter with SRCU
Date
From: Like Xu <likexu@tencent.com>

Similar to "kvm->arch.msr_filter", KVM should guarantee that vCPUs will
see either the previous filter or the new filter when user space calls
KVM_SET_PMU_EVENT_FILTER ioctl with the vCPU running so that guest
pmu events with identical settings in both the old and new filter have
deterministic behavior.

Fixes: 66bb8a065f5a ("KVM: x86: PMU Event Filter")
Signed-off-by: Like Xu <likexu@tencent.com>
Reviewed-by: Wanpeng Li <wanpengli@tencent.com>
---
arch/x86/kvm/pmu.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index f189512207db..24624654e476 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -246,8 +246,9 @@ static bool check_pmu_event_filter(struct kvm_pmc *pmc)
struct kvm *kvm = pmc->vcpu->kvm;
bool allow_event = true;
__u64 key;
- int idx;
+ int idx, srcu_idx;

+ srcu_idx = srcu_read_lock(&kvm->srcu);
filter = srcu_dereference(kvm->arch.pmu_event_filter, &kvm->srcu);
if (!filter)
goto out;
@@ -270,6 +271,7 @@ static bool check_pmu_event_filter(struct kvm_pmc *pmc)
}

out:
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
return allow_event;
}

--
2.36.1
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