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authorLan Tianyu <tianyu.lan@intel.com>2016-03-13 11:10:24 +0800
committerPaolo Bonzini <pbonzini@redhat.com>2016-03-22 16:38:27 +0100
commit9753f529156d03112d1ff6f3758ccd6fa6faf189 (patch)
tree675585108c6efb772d2d0503468fcef602237044 /arch
parentb9baba861489041b37b54fc7ee0b0006b5327151 (diff)
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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kvm/mmu.c15
1 files changed, 7 insertions, 8 deletions
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index e46a81f4856e..fc8ab1f67d00 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -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);

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