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From:   Sean Christopherson <sean.j.christopherson@intel.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Sean Christopherson <sean.j.christopherson@intel.com>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Jim Mattson <jmattson@google.com>,
        Joerg Roedel <joro@8bytes.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, Junaid Shahid <junaids@google.com>
Subject: [PATCH 1/8] KVM: x86/mmu: Commit zap of remaining invalid pages when recovering lpages
Date:   Tue, 14 Jul 2020 21:27:18 -0700
Message-Id: <20200715042725.10961-2-sean.j.christopherson@intel.com>
In-Reply-To: <20200715042725.10961-1-sean.j.christopherson@intel.com>
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Call kvm_mmu_commit_zap_page() after exiting the "prepare zap" loop in
kvm_recover_nx_lpages() to finish zapping pages in the unlikely event
that the loop exited due to lpage_disallowed_mmu_pages being empty.
Because the recovery thread drops mmu_lock() when rescheduling, it's
possible that lpage_disallowed_mmu_pages could be emptied by a different
thread without to_zap reaching zero despite to_zap being derived from
the number of disallowed lpages.

Fixes: 1aa9b9572b105 ("kvm: x86: mmu: Recovery of shattered NX large pages")
Cc: Junaid Shahid <junaids@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/mmu/mmu.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 77810ce66bdb4..48be51027af64 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6340,6 +6340,7 @@ static void kvm_recover_nx_lpages(struct kvm *kvm)
 				cond_resched_lock(&kvm->mmu_lock);
 		}
 	}
+	kvm_mmu_commit_zap_page(kvm, &invalid_list);
 
 	spin_unlock(&kvm->mmu_lock);
 	srcu_read_unlock(&kvm->srcu, rcu_idx);
-- 
2.26.0