KVM: x86/mmu: Do remote TLB flush before dropping RCU in TDP MMU resched

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

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Message-Id: <20220226001546.360188-19-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index c71debdbc73239b4b849af8ecb638c769ae00386..3a866fcb5ea94f3153f4821b8c76601d0f457686 100644 (file)
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -716,11 +716,11 @@ static inline bool __must_check 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