Re: [kvm-unit-tests PATCH 5/7] virtio: implement the virtio_add_inbuf routine

[Pierre Morel <pmorel@linux.ibm.com>]

On 11/3/21 08:51, Andrew Jones wrote:
> On Fri, Aug 27, 2021 at 12:17:18PM +0200, Pierre Morel wrote:
>> To communicate in both directions with a VIRTIO device we need
>> to add the incoming communication to the VIRTIO level.
>>
>> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
>> ---
>>   lib/virtio.c | 32 ++++++++++++++++++++++++++++++++
>>   lib/virtio.h |  2 ++
>>   2 files changed, 34 insertions(+)
>>
>> diff --git a/lib/virtio.c b/lib/virtio.c
>> index e10153b9..b84bc680 100644
>> --- a/lib/virtio.c
>> +++ b/lib/virtio.c
>> @@ -47,6 +47,38 @@ void vring_init_virtqueue(struct vring_virtqueue *vq, unsigned index,
>>   	vq->data[i] = NULL;
>>   }
>>   
>> +int virtqueue_add_inbuf(struct virtqueue *_vq, char *buf, unsigned int len)
>> +{
>> +	struct vring_virtqueue *vq = to_vvq(_vq);
>> +	unsigned int avail;
>> +	int head;
>> +
>> +	assert(buf);
>> +	assert(len);
>> +
>> +	if (!vq->vq.num_free)
>> +		return -1;
>> +
>> +	--vq->vq.num_free;
>> +
>> +	head = vq->free_head;
>> +
>> +	vq->vring.desc[head].flags = 0;
>> +	vq->vring.desc[head].addr = virt_to_phys(buf);
>> +	vq->vring.desc[head].len = len;
>> +
>> +	vq->free_head = vq->vring.desc[head].next;
>> +
>> +	vq->data[head] = buf;
>> +
>> +	avail = (vq->vring.avail->idx & (vq->vring.num - 1));
>> +	vq->vring.avail->ring[avail] = head;
>> +	wmb();	/* be sure to update the ring before updating the idx */
>> +	vq->vring.avail->idx++;
>> +	vq->num_added++;
>> +
>> +	return 0;
>> +}
>>   int virtqueue_add_outbuf(struct virtqueue *_vq, char *buf, unsigned int len)
>>   {
>>   	struct vring_virtqueue *vq = to_vvq(_vq);
>> diff --git a/lib/virtio.h b/lib/virtio.h
>> index 2c31fdc7..44b727f8 100644
>> --- a/lib/virtio.h
>> +++ b/lib/virtio.h
>> @@ -141,6 +141,8 @@ extern void vring_init_virtqueue(struct vring_virtqueue *vq, unsigned index,
>>   				 const char *name);
>>   extern int virtqueue_add_outbuf(struct virtqueue *vq, char *buf,
>>   				unsigned int len);
>> +extern int virtqueue_add_inbuf(struct virtqueue *vq, char *buf,
>> +			       unsigned int len);
>>   extern bool virtqueue_kick(struct virtqueue *vq);
>>   extern void detach_buf(struct vring_virtqueue *vq, unsigned head);
>>   extern void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len);
>> -- 
>> 2.25.1
>>
> 
> Reviewed-by: Andrew Jones <drjones@redhat.com>
> 

Thanks,
Pierre


-- 
Pierre Morel
IBM Lab Boeblingen