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

commit 0823dc64586ba5ea13a7d200a5d33e4c5fa45950 upstream.

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 <dtatulea@nvidia.com>
Tested-by: Dragos Tatulea <dtatulea@nvidia.com>
Fixes: ddd89d0a

 ("vhost_vdpa: support doorbell mapping via mmap")
Cc: stable@vger.kernel.org
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20240701033159.18133-1-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>