Merge branch 'drm-next-4.6' of git://people.freedesktop.org/~agd5f/linux into drm...

[deliverable/linux.git] / arch / x86 / kvm / mmu.c

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index e46a81f4856e6f212e383f7f2c39b7a9c59712b8..70e95d097ef104ac489a41a17dce2296dad5123c 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -479,7 +479,7 @@ static bool spte_is_locklessly_modifiable(u64 spte)
 static bool spte_has_volatile_bits(u64 spte)
 {
        /*
-        * Always atomicly update spte if it can be updated
+        * Always atomically update spte if it can be updated
         * out of mmu-lock, it can ensure dirty bit is not lost,
         * also, it can help us to get a stable is_writable_pte()
         * to ensure tlb flush is not missed.
@@ -550,7 +550,7 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte)
 
        /*
         * For the spte updated out of mmu-lock is safe, since
-        * we always atomicly update it, see the comments in
+        * we always atomically update it, see the comments in
         * spte_has_volatile_bits().
         */
        if (spte_is_locklessly_modifiable(old_spte) &&
@@ -632,12 +632,12 @@ static void walk_shadow_page_lockless_begin(struct kvm_vcpu *vcpu)
         * kvm_flush_remote_tlbs() IPI to all active vcpus.
         */
        local_irq_disable();
-       vcpu->mode = READING_SHADOW_PAGE_TABLES;
+
        /*
         * Make sure a following spte read is not reordered ahead of the write
         * to vcpu->mode.
         */
-       smp_mb();
+       smp_store_mb(vcpu->mode, READING_SHADOW_PAGE_TABLES);
 }
 
 static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
@@ -647,8 +647,7 @@ static void walk_shadow_page_lockless_end(struct kvm_vcpu *vcpu)
         * reads to sptes.  If it does, kvm_commit_zap_page() can see us
         * OUTSIDE_GUEST_MODE and proceed to free the shadow page table.
         */
-       smp_mb();
-       vcpu->mode = OUTSIDE_GUEST_MODE;
+       smp_store_release(&vcpu->mode, OUTSIDE_GUEST_MODE);
        local_irq_enable();
 }
 
@@ -2390,14 +2389,13 @@ 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);