linux-kernel - [PATCH 3/4] KVM: x86/mmu: Fix RCU usage when atomically zapping SPTEs

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Message-Id: <20210311231658.1243953-4-bgardon@google.com>
Date:   Thu, 11 Mar 2021 15:16:57 -0800
From:   Ben Gardon <bgardon@...gle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        Jim Mattson <jmattson@...gle.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH 3/4] KVM: x86/mmu: Fix RCU usage when atomically zapping SPTEs

Fix a missing rcu_dereference in tdp_mmu_zap_spte_atomic.

Reported-by: kernel test robot <lkp@...xxxxxx>
Signed-off-by: Ben Gardon <bgardon@...gle.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 6c8824bcc2f2..a8fdccf4fd06 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -532,7 +532,7 @@ static inline bool tdp_mmu_zap_spte_atomic(struct kvm *kvm,
 	 * here since the SPTE is going from non-present
 	 * to non-present.
 	 */
-	WRITE_ONCE(*iter->sptep, 0);
+	WRITE_ONCE(*rcu_dereference(iter->sptep), 0);
 
 	return true;
 }
-- 
2.31.0.rc2.261.g7f71774620-goog