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Re: [Qemu-devel] [PATCH v2 4/5] vhost: move virtio 1.0 check to cross-en
From: |
Laurent Vivier |
Subject: |
Re: [Qemu-devel] [PATCH v2 4/5] vhost: move virtio 1.0 check to cross-endian helper |
Date: |
Tue, 12 Jan 2016 01:23:56 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.4.0 |
On 11/01/2016 17:13, Greg Kurz wrote:
> Indeed vhost doesn't need to ask for vring endian fixing if the device is
> virtio 1.0, since it is already handled by the in-kernel vhost driver. This
> patch simply consolidates the logic into the existing helper.
>
> Signed-off-by: Greg Kurz <address@hidden>
> Reviewed-by: Cornelia Huck <address@hidden>
> ---
> hw/virtio/vhost.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index 2e1e792d599e..aef750df22ad 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -750,6 +750,9 @@ static void vhost_log_stop(MemoryListener *listener,
>
> static inline bool vhost_needs_vring_endian(VirtIODevice *vdev)
> {
> + if (virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1)) {
> + return false;
> + }
> #ifdef TARGET_IS_BIENDIAN
> #ifdef HOST_WORDS_BIGENDIAN
> return !virtio_is_big_endian(vdev);
I'm wondering if in term of performance you can remove the call of
virtio_vdev_has_feature() as it is done in virtio_is_big_endian().
> @@ -811,8 +814,7 @@ static int vhost_virtqueue_start(struct vhost_dev *dev,
> return -errno;
> }
>
> - if (!virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1) &&
> - vhost_needs_vring_endian(vdev)) {
> + if (vhost_needs_vring_endian(vdev)) {
> r = vhost_virtqueue_set_vring_endian_legacy(dev,
>
> virtio_is_big_endian(vdev),
> vhost_vq_index);
> @@ -908,8 +910,7 @@ static void vhost_virtqueue_stop(struct vhost_dev *dev,
> /* In the cross-endian case, we need to reset the vring endianness to
> * native as legacy devices expect so by default.
> */
> - if (!virtio_vdev_has_feature(vdev, VIRTIO_F_VERSION_1) &&
> - vhost_needs_vring_endian(vdev)) {
> + if (vhost_needs_vring_endian(vdev)) {
> r = vhost_virtqueue_set_vring_endian_legacy(dev,
>
> !virtio_is_big_endian(vdev),
> vhost_vq_index);
>
>
- Re: [Qemu-devel] [PATCH v2 1/5] virtio-net: use the backend cross-endian capabilities, (continued)
- Re: [Qemu-devel] [PATCH v2 1/5] virtio-net: use the backend cross-endian capabilities, Laurent Vivier, 2016/01/11
- Re: [Qemu-devel] [PATCH v2 1/5] virtio-net: use the backend cross-endian capabilities, Laurent Vivier, 2016/01/12
- Re: [Qemu-devel] [PATCH v2 1/5] virtio-net: use the backend cross-endian capabilities, Greg Kurz, 2016/01/13
- Re: [Qemu-devel] [PATCH v2 1/5] virtio-net: use the backend cross-endian capabilities, Laurent Vivier, 2016/01/13
- Re: [Qemu-devel] [PATCH v2 1/5] virtio-net: use the backend cross-endian capabilities, Greg Kurz, 2016/01/13
[Qemu-devel] [PATCH v2 2/5] Revert "vhost-net: tell tap backend about the vnet endianness", Greg Kurz, 2016/01/11
[Qemu-devel] [PATCH v2 3/5] virtio: move cross-endian helper to vhost, Greg Kurz, 2016/01/11
[Qemu-devel] [PATCH v2 4/5] vhost: move virtio 1.0 check to cross-endian helper, Greg Kurz, 2016/01/11
[Qemu-devel] [PATCH v2 5/5] virtio: optimize virtio_access_is_big_endian() for little-endian targets, Greg Kurz, 2016/01/11