Reply-To: Sean Christopherson <seanjc@google.com>
Date:   Sat, 20 Nov 2021 04:50:45 +0000
In-Reply-To: <20211120045046.3940942-1-seanjc@google.com>
Message-Id: <20211120045046.3940942-28-seanjc@google.com>
Mime-Version: 1.0
References: <20211120045046.3940942-1-seanjc@google.com>
Subject: [PATCH 27/28] KVM: x86/mmu: Do remote TLB flush before dropping RCU
 in TDP MMU resched
From:   Sean Christopherson <seanjc@google.com>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Sean Christopherson <seanjc@google.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,
        Hou Wenlong <houwenlong93@linux.alibaba.com>,
        Ben Gardon <bgardon@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

When yielding in the TDP MMU iterator, service any pending TLB flush
before  dropping RCU protections in anticipation of using the callers RCU
"lock" as a proxy for vCPUs in the guest.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 79a52717916c..55c16680b927 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -732,11 +732,11 @@ static inline bool tdp_mmu_iter_cond_resched(struct kvm *kvm,
 		return false;
 
 	if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) {
-		rcu_read_unlock();
-
 		if (flush)
 			kvm_flush_remote_tlbs(kvm);
 
+		rcu_read_unlock();
+
 		if (shared)
 			cond_resched_rwlock_read(&kvm->mmu_lock);
 		else
-- 
2.34.0.rc2.393.gf8c9666880-goog