KVM: MMU: Add locking around kvm_mmu_slot_remove_write_access()

(cherry picked from commit 2245a28fe2e6fdb1bdabc4dcde1ea3a5c37e2a9e)

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 3da2508..32aa0b8 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2055,6 +2055,7 @@ 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;
@@ -2068,6 +2069,7 @@ 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)