Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
From:   Like Xu <like.xu.linux@gmail.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Sean Christopherson <seanjc@google.com>,
        Jim Mattson <jmattson@google.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Joerg Roedel <joro@8bytes.org>, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
Subject: [PATCH RESEND v3 03/11] KVM: x86/pmu: Protect kvm->arch.pmu_event_filter with SRCU
Date:   Wed, 18 May 2022 21:25:04 +0800
Message-Id: <20220518132512.37864-4-likexu@tencent.com>
In-Reply-To: <20220518132512.37864-1-likexu@tencent.com>
References: <20220518132512.37864-1-likexu@tencent.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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