KVM: MMU: protect kvm_mmu_change_mmu_pages with mmu_lock

kvm_handle_hva, called by MMU notifiers, manipulates mmu data only with
the protection of mmu_lock.

Update kvm_mmu_change_mmu_pages callers to take mmu_lock, thus protecting
against kvm_handle_hva.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

2 files changed, 6 insertions, 2 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index bc614f91f5ba..3ce60ad1fe37 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2723,7 +2723,6 @@ 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;
@@ -2738,7 +2737,6 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
                                 pt[i] &= ~PT_WRITABLE_MASK;
         }
         kvm_flush_remote_tlbs(kvm);
-        spin_unlock(&kvm->mmu_lock);
 }
 
 void kvm_mmu_zap_all(struct kvm *kvm)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 48f744ff0bc1..d2a4eca26181 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1625,10 +1625,12 @@ static int kvm_vm_ioctl_set_nr_mmu_pages(struct kvm *kvm,
                 return -EINVAL;
 
         down_write(&kvm->slots_lock);
+        spin_lock(&kvm->mmu_lock);
 
         kvm_mmu_change_mmu_pages(kvm, kvm_nr_mmu_pages);
         kvm->arch.n_requested_mmu_pages = kvm_nr_mmu_pages;
 
+        spin_unlock(&kvm->mmu_lock);
         up_write(&kvm->slots_lock);
         return 0;
 }
@@ -1804,7 +1806,9 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 
         /* If nothing is dirty, don't bother messing with page tables. */
         if (is_dirty) {
+                spin_lock(&kvm->mmu_lock);
                 kvm_mmu_slot_remove_write_access(kvm, log->slot);
+                spin_unlock(&kvm->mmu_lock);
                 kvm_flush_remote_tlbs(kvm);
                 memslot = &kvm->memslots[log->slot];
                 n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
@@ -4548,12 +4552,14 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
                 }
         }
 
+        spin_lock(&kvm->mmu_lock);
         if (!kvm->arch.n_requested_mmu_pages) {
                 unsigned int nr_mmu_pages = kvm_mmu_calculate_mmu_pages(kvm);
                 kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
         }
 
         kvm_mmu_slot_remove_write_access(kvm, mem->slot);
+        spin_unlock(&kvm->mmu_lock);
         kvm_flush_remote_tlbs(kvm);
 
         return 0;