kvm: x86/mmu: Flush TLB before zap_gfn_range releases RCU

Since "KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()"
is going to be reverted, it's not going to be true anymore that
the zap-page flow does not free any 'struct kvm_mmu_page'.  Introduce
an early flush before tdp_mmu_zap_leafs() returns, to preserve
bisectability.

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 af60922..7f63e1a 100644 (file)
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -941,13 +941,17 @@ static bool tdp_mmu_zap_leafs(struct kvm *kvm, struct kvm_mmu_page *root,
                flush = true;
        }
 
-       rcu_read_unlock();
-
        /*
-        * Because this flow zaps _only_ leaf SPTEs, the caller doesn't need
-        * to provide RCU protection as no 'struct kvm_mmu_page' will be freed.
+        * Need to flush before releasing RCU.  TODO: do it only if intermediate
+        * page tables were zapped; there is no need to flush under RCU protection
+        * if no 'struct kvm_mmu_page' is freed.
         */
-       return flush;
+       if (flush)
+               kvm_flush_remote_tlbs_with_address(kvm, start, end - start);
+
+       rcu_read_unlock();
+
+       return false;
 }
 
 /*