KVM: MMU: Switch to mmu spinlock

Convert the synchronization of the shadow handling to a separate mmu_lock
spinlock.

Also guard fetch() by mmap_sem in read-mode to protect against alias
and memslot changes.

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

1 files changed, 1 insertions, 2 deletions

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 8d0b7c16c2f7..3c4fe26096fc 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -165,6 +165,7 @@ static struct kvm *kvm_create_vm(void)
 
         kvm->mm = current->mm;
         atomic_inc(&kvm->mm->mm_count);
+        spin_lock_init(&kvm->mmu_lock);
         kvm_io_bus_init(&kvm->pio_bus);
         mutex_init(&kvm->lock);
         kvm_io_bus_init(&kvm->mmio_bus);
@@ -552,9 +553,7 @@ int kvm_read_guest_atomic(struct kvm *kvm, gpa_t gpa, void *data,
         addr = gfn_to_hva(kvm, gfn);
         if (kvm_is_error_hva(addr))
                 return -EFAULT;
-        pagefault_disable();
         r = __copy_from_user_inatomic(data, (void __user *)addr + offset, len);
-        pagefault_enable();
         if (r)
                 return -EFAULT;
         return 0;