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Tiwei Bie

2018-Oct-12 14:32 UTC

[PATCH net-next V2 6/8] vhost: packed ring support

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?

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.
> +		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.

> +		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;[...]

Michael S. Tsirkin

2018-Oct-12 17:23 UTC

head link

[PATCH net-next V2 6/8] vhost: packed ring support

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.

> 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.
> 
> > +		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.
> 
> 
> > +		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;
> [...]

Jason Wang

2018-Oct-15 02:22 UTC

head link

[PATCH net-next V2 6/8] vhost: packed ring support

On 2018?10?13? 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;
>> [...]

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