KVM: MMU: Add locking around kvm_mmu_slot_remove_write_access()

It was generally safe due to slots_lock being held for write, but it wasn't
very nice.

Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index a24da8f2ee91..5052acdc0a77 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2097,6 +2097,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
 {
         struct kvm_mmu_page *sp;
 
+        spin_lock(&kvm->mmu_lock);
         list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) {
                 int i;
                 u64 *pt;
@@ -2110,6 +2111,7 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
                         if (pt[i] & PT_WRITABLE_MASK)
                                 pt[i] &= ~PT_WRITABLE_MASK;
         }
+        spin_unlock(&kvm->mmu_lock);
 }
 
 void kvm_mmu_zap_all(struct kvm *kvm)