KVM: Remove redundant smp_mb() in the kvm_mmu_commit_zap_page()
There is already a barrier inside of kvm_flush_remote_tlbs() which can
help to make sure everyone sees our modifications to the page tables and
see changes to vcpu->mode here. So remove the smp_mb in the
kvm_mmu_commit_zap_page() and update the comment.
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index e46a81f..fc8ab1f 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2390,14 +2390,13 @@
return;
/*
- * wmb: make sure everyone sees our modifications to the page tables
- * rmb: make sure we see changes to vcpu->mode
- */
- smp_mb();
-
- /*
- * Wait for all vcpus to exit guest mode and/or lockless shadow
- * page table walks.
+ * We need to make sure everyone sees our modifications to
+ * the page tables and see changes to vcpu->mode here. The barrier
+ * in the kvm_flush_remote_tlbs() achieves this. This pairs
+ * with vcpu_enter_guest and walk_shadow_page_lockless_begin/end.
+ *
+ * In addition, kvm_flush_remote_tlbs waits for all vcpus to exit
+ * guest mode and/or lockless shadow page table walks.
*/
kvm_flush_remote_tlbs(kvm);