From: Jason Wang <jasowang@redhat.com>
To: "Michael S. Tsirkin" <mst@redhat.com>, Tiwei Bie <tiwei.bie@intel.com>
Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
wexu@redhat.com, jfreimann@redhat.com,
maxime.coquelin@redhat.com
Subject: Re: [PATCH net-next V2 6/8] vhost: packed ring support
Date: Mon, 15 Oct 2018 10:22:33 +0800 [thread overview]
Message-ID: <447f47fa-32dd-a408-dd81-13a9839e0748@redhat.com> (raw)
In-Reply-To: <20181012131812-mutt-send-email-mst@kernel.org>
On 2018年10月13日 01:23, Michael S. Tsirkin wrote:
> On Fri, Oct 12, 2018 at 10:32:44PM +0800, Tiwei Bie wrote:
>> On Mon, Jul 16, 2018 at 11:28:09AM +0800, Jason Wang wrote:
>> [...]
>>> @@ -1367,10 +1397,48 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg
>>> vq->last_avail_idx = s.num;
>>> /* Forget the cached index value. */
>>> vq->avail_idx = vq->last_avail_idx;
>>> + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
>>> + vq->last_avail_wrap_counter = wrap_counter;
>>> + vq->avail_wrap_counter = vq->last_avail_wrap_counter;
>>> + }
>>> break;
>>> case VHOST_GET_VRING_BASE:
>>> s.index = idx;
>>> s.num = vq->last_avail_idx;
>>> + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
>>> + s.num |= vq->last_avail_wrap_counter << 31;
>>> + if (copy_to_user(argp, &s, sizeof(s)))
>>> + r = -EFAULT;
>>> + break;
>>> + case VHOST_SET_VRING_USED_BASE:
>>> + /* Moving base with an active backend?
>>> + * You don't want to do that.
>>> + */
>>> + if (vq->private_data) {
>>> + r = -EBUSY;
>>> + break;
>>> + }
>>> + if (copy_from_user(&s, argp, sizeof(s))) {
>>> + r = -EFAULT;
>>> + break;
>>> + }
>>> + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) {
>>> + wrap_counter = s.num >> 31;
>>> + s.num &= ~(1 << 31);
>>> + }
>>> + if (s.num > 0xffff) {
>>> + r = -EINVAL;
>>> + break;
>>> + }
>> Do we want to put wrap_counter at bit 15?
> I think I second that - seems to be consistent with
> e.g. event suppression structure and the proposed
> extension to driver notifications.
Ok, I assumes packed virtqueue support 64K but looks not. I can change
it to bit 15 and GET_VRING_BASE need to be changed as well.
>
>
>> If put wrap_counter at bit 31, the check (s.num > 0xffff)
>> won't be able to catch the illegal index 0x8000~0xffff for
>> packed ring.
>>
Do we need to clarify this in the spec?
>>> + vq->last_used_idx = s.num;
>>> + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
>>> + vq->last_used_wrap_counter = wrap_counter;
>>> + break;
>>> + case VHOST_GET_VRING_USED_BASE:
>> Do we need the new VHOST_GET_VRING_USED_BASE and
>> VHOST_SET_VRING_USED_BASE ops?
>>
>> We are going to merge below series in DPDK:
>>
>> http://patches.dpdk.org/patch/45874/
>>
>> We may need to reach an agreement first.
If we agree that 64K virtqueue won't be supported, I'm ok with either.
Btw the code assumes used_wrap_counter is equal to avail_wrap_counter
which looks wrong?
Thanks
>>
>>> + s.index = idx;
>>> + s.num = vq->last_used_idx;
>>> + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED))
>>> + s.num |= vq->last_used_wrap_counter << 31;
>>> if (copy_to_user(argp, &s, sizeof s))
>>> r = -EFAULT;
>>> break;
>> [...]
next prev parent reply other threads:[~2018-10-15 2:22 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-16 3:28 [PATCH net-next V2 0/8] Packed virtqueue support for vhost Jason Wang
2018-07-16 3:28 ` [PATCH net-next V2 1/8] vhost: move get_rx_bufs to vhost.c Jason Wang
2018-07-16 3:28 ` [PATCH net-next V2 2/8] vhost: hide used ring layout from device Jason Wang
2018-07-16 3:28 ` [PATCH net-next V2 3/8] vhost: do not use vring_used_elem Jason Wang
2018-07-16 3:28 ` [PATCH net-next V2 4/8] vhost_net: do not explicitly manipulate vhost_used_elem Jason Wang
2018-07-16 3:28 ` [PATCH net-next V2 5/8] vhost: vhost_put_user() can accept metadata type Jason Wang
2018-07-16 3:28 ` [PATCH net-next V2 6/8] vhost: packed ring support Jason Wang
2018-10-12 14:32 ` Tiwei Bie
2018-10-12 17:23 ` Michael S. Tsirkin
2018-10-15 2:22 ` Jason Wang [this message]
2018-10-15 2:43 ` Michael S. Tsirkin
2018-10-15 2:51 ` Jason Wang
2018-10-15 10:25 ` Michael S. Tsirkin
2018-10-18 2:44 ` Jason Wang
2018-10-16 13:58 ` Maxime Coquelin
2018-10-17 6:54 ` Jason Wang
2018-10-17 12:02 ` Maxime Coquelin
2018-07-16 3:28 ` [PATCH net-next V2 7/8] vhost: event suppression for packed ring Jason Wang
2018-07-16 3:28 ` [PATCH net-next V2 8/8] vhost: enable packed virtqueues Jason Wang
2018-07-16 8:39 ` [PATCH net-next V2 0/8] Packed virtqueue support for vhost Michael S. Tsirkin
2018-07-16 9:46 ` Jason Wang
2018-07-16 12:49 ` Michael S. Tsirkin
2018-07-17 0:45 ` Jason Wang
2018-07-22 16:56 ` Michael S. Tsirkin
2018-07-18 4:09 ` David Miller
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