Re: [PATCH v7 00/19] virtio: alignment issues

From: Jason Wang
Date: Mon Apr 06 2020 - 23:41:51 EST


----- Original Message -----
>
> This is an alternative to
> vhost: force spec specified alignment on types
> which is a bit safer as it does not change UAPI.
> I still think it's best to change the UAPI header as well,
> we can do that as a follow-up cleanup.
>
> changes from v6:
> add missing header includes all over the place
> changes from v5:
> ack for mellanox patch
> fixup to remoteproc
> changes from v4:
> fixup to issues reported by kbuild
> changes from v3:
> tools/virtio fixes
> a bunch more cleanups that now become possible
>
> Changes from v2:
> don't change struct name, instead add ifndef
> so kernel does not see the legacy UAPI version.
>
> Jason, can you pls ack one of the approaches?

I prefer this approach but it looks a little bit risky for 5.7. Can we
do this in 5.8?

Instead of using Kconfig, could we simply fail the initalization of
vhost like:

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 0395229486a9..e9f6a008ed12 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -2636,6 +2636,11 @@ EXPORT_SYMBOL_GPL(vhost_dequeue_msg);

static int __init vhost_init(void)
{
+ struct vhost_virtqueue *vq;
+
+ if (__alignof__ *vq->avail > VRING_AVAIL_ALIGN_SIZE)
+ return -ENOTSUPP;
+
return 0;
}

Thanks

>
>
> Matej Genci (1):
> virtio: add VIRTIO_RING_NO_LEGACY
>
> Michael S. Tsirkin (18):
> tools/virtio: define aligned attribute
> tools/virtio: make asm/barrier.h self contained
> tools/virtio: define __KERNEL__
> virtgpu: pull in uaccess.h
> virtio-rng: pull in slab.h
> remoteproc: pull in slab.h
> virtio_input: pull in slab.h
> virtio: stop using legacy struct vring in kernel
> vhost: force spec specified alignment on types
> virtio: add legacy init/size APIs
> virtio_ring: switch to virtio_legacy_init/size
> tools/virtio: switch to virtio_legacy_init/size
> vop: switch to virtio_legacy_init/size
> remoteproc: switch to virtio_legacy_init/size
> mellanox: switch to virtio_legacy_init/size
> vhost: option to fetch descriptors through an independent struct
> vhost: use batched version by default
> vhost: batching fetches
>
> drivers/block/virtio_blk.c | 1 +
> drivers/char/hw_random/virtio-rng.c | 1 +
> drivers/gpu/drm/virtio/virtgpu_ioctl.c | 1 +
> drivers/misc/mic/vop/vop_main.c | 5 +-
> drivers/misc/mic/vop/vop_vringh.c | 8 +-
> drivers/platform/mellanox/mlxbf-tmfifo.c | 6 +-
> drivers/remoteproc/remoteproc_core.c | 2 +-
> drivers/remoteproc/remoteproc_sysfs.c | 1 +
> drivers/remoteproc/remoteproc_virtio.c | 2 +-
> drivers/vhost/test.c | 2 +-
> drivers/vhost/vhost.c | 271 +++++++++++++++--------
> drivers/vhost/vhost.h | 23 +-
> drivers/virtio/virtio_input.c | 1 +
> drivers/virtio/virtio_pci_modern.c | 1 +
> drivers/virtio/virtio_ring.c | 15 +-
> include/linux/virtio.h | 1 -
> include/linux/virtio_ring.h | 46 ++++
> include/linux/vringh.h | 1 +
> include/uapi/linux/virtio_ring.h | 30 ++-
> tools/virtio/Makefile | 2 +-
> tools/virtio/asm/barrier.h | 1 +
> tools/virtio/linux/compiler.h | 1 +
> tools/virtio/ringtest/virtio_ring_0_9.c | 6 +-
> tools/virtio/virtio_test.c | 6 +-
> tools/virtio/vringh_test.c | 18 +-
> 25 files changed, 311 insertions(+), 141 deletions(-)
>
> --
> MST
>
>

>