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Commit 9753f529 authored by Lan Tianyu's avatar Lan Tianyu Committed by Paolo Bonzini
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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: default avatarLan Tianyu <tianyu.lan@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent b9baba86

arch/x86/kvm/mmu.c

+7 −8
Original line number Diff line number Diff line
@@ -2390,14 +2390,13 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm, 
		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);