vhost-vdpa: switch to use vmf_insert_pfn() in the fault handler

remap_pfn_page() should not be called in the fault handler as it may
change the vma->flags which may trigger lockdep warning since the vma
write lock is not held. Actually there's no need to modify the
vma->flags as it has been set in the mmap(). So this patch switches to
use vmf_insert_pfn() instead.

Reported-by: Dragos Tatulea <[email protected]>
Tested-by: Dragos Tatulea <[email protected]>
Fixes: ddd89d0 ("vhost_vdpa: support doorbell mapping via mmap")
Cc: [email protected]
Signed-off-by: Jason Wang <[email protected]>
Message-Id: <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
Reviewed-by: Michal Kubiak <[email protected]>

Author: jasowang

drivers/vhost/vdpa.c

@@ -1483,13 +1483,7 @@ static vm_fault_t vhost_vdpa_fault(struct vm_fault *vmf)
 
 	notify = ops->get_vq_notification(vdpa, index);
 
-	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
-	if (remap_pfn_range(vma, vmf->address & PAGE_MASK,
-			    PFN_DOWN(notify.addr), PAGE_SIZE,
-			    vma->vm_page_prot))
-		return VM_FAULT_SIGBUS;
-
-	return VM_FAULT_NOPAGE;
+	return vmf_insert_pfn(vma, vmf->address & PAGE_MASK, PFN_DOWN(notify.addr));
 }
 
 static const struct vm_operations_struct vhost_vdpa_vm_ops = {