diff mbox series

[1/4] net/virtio: fix the control vq support

Message ID 20190122170143.5650-2-tiwei.bie@intel.com (mailing list archive)
State Accepted, archived
Delegated to: Maxime Coquelin
Headers
Series Virtio fixes |

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK
ci/mellanox-Performance-Testing success Performance Testing PASS
ci/intel-Performance-Testing success Performance Testing PASS

Commit Message

Tiwei Bie Jan. 22, 2019, 5:01 p.m. UTC 
This patch mainly fixed below issues in the packed ring based
control vq support in virtio driver:

1. When parsing the used descriptors, we have to track the
   number of descs that we need to skip;
2. vq->vq_free_cnt was decreased twice for a same desc;

Meanwhile, make the function name consistent with other parts.

Fixes: ec194c2f1895 ("net/virtio: support packed queue in send command")
Fixes: a4270ea4ff79 ("net/virtio: check head desc with correct wrap counter")

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
---
 drivers/net/virtio/virtio_ethdev.c | 62 ++++++++++++++----------------
 drivers/net/virtio/virtqueue.h     | 12 +-----
 2 files changed, 31 insertions(+), 43 deletions(-)

Comments

Ilya Maximets Jan. 23, 2019, 1:09 p.m. UTC | #1 
On 22.01.2019 20:01, Tiwei Bie wrote:
> This patch mainly fixed below issues in the packed ring based
> control vq support in virtio driver:
> 
> 1. When parsing the used descriptors, we have to track the
>    number of descs that we need to skip;
> 2. vq->vq_free_cnt was decreased twice for a same desc;
> 
> Meanwhile, make the function name consistent with other parts.
> 
> Fixes: ec194c2f1895 ("net/virtio: support packed queue in send command")
> Fixes: a4270ea4ff79 ("net/virtio: check head desc with correct wrap counter")
> 
> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> ---
>  drivers/net/virtio/virtio_ethdev.c | 62 ++++++++++++++----------------
>  drivers/net/virtio/virtqueue.h     | 12 +-----
>  2 files changed, 31 insertions(+), 43 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index ee5a98b7c..a3fe65599 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -142,16 +142,17 @@ static const struct rte_virtio_xstats_name_off rte_virtio_txq_stat_strings[] = {
>  struct virtio_hw_internal virtio_hw_internal[RTE_MAX_ETHPORTS];
>  
>  static struct virtio_pmd_ctrl *
> -virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
> -		       int *dlen, int pkt_num)
> +virtio_send_command_packed(struct virtnet_ctl *cvq,
> +			   struct virtio_pmd_ctrl *ctrl,
> +			   int *dlen, int pkt_num)
>  {
>  	struct virtqueue *vq = cvq->vq;
>  	int head;
>  	struct vring_packed_desc *desc = vq->ring_packed.desc_packed;
>  	struct virtio_pmd_ctrl *result;
> -	bool avail_wrap_counter, used_wrap_counter;
> -	uint16_t flags;
> +	bool avail_wrap_counter;
>  	int sum = 0;
> +	int nb_descs = 0;
>  	int k;
>  
>  	/*
> @@ -162,11 +163,10 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>  	 */
>  	head = vq->vq_avail_idx;
>  	avail_wrap_counter = vq->avail_wrap_counter;
> -	used_wrap_counter = vq->used_wrap_counter;
> -	desc[head].flags = VRING_DESC_F_NEXT;
>  	desc[head].addr = cvq->virtio_net_hdr_mem;
>  	desc[head].len = sizeof(struct virtio_net_ctrl_hdr);
>  	vq->vq_free_cnt--;
> +	nb_descs++;
>  	if (++vq->vq_avail_idx >= vq->vq_nentries) {
>  		vq->vq_avail_idx -= vq->vq_nentries;
>  		vq->avail_wrap_counter ^= 1;
> @@ -177,55 +177,51 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>  			+ sizeof(struct virtio_net_ctrl_hdr)
>  			+ sizeof(ctrl->status) + sizeof(uint8_t) * sum;
>  		desc[vq->vq_avail_idx].len = dlen[k];
> -		flags = VRING_DESC_F_NEXT;

Looks like barriers was badly placed here before this patch.
Anyway, you need a write barrier here between {addr, len} and flags updates.

> +		desc[vq->vq_avail_idx].flags = VRING_DESC_F_NEXT |
> +			VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
> +			VRING_DESC_F_USED(!vq->avail_wrap_counter);
>  		sum += dlen[k];
>  		vq->vq_free_cnt--;
> -		flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
> -			 VRING_DESC_F_USED(!vq->avail_wrap_counter);
> -		desc[vq->vq_avail_idx].flags = flags;
> -		rte_smp_wmb();
> -		vq->vq_free_cnt--;
> +		nb_descs++;
>  		if (++vq->vq_avail_idx >= vq->vq_nentries) {
>  			vq->vq_avail_idx -= vq->vq_nentries;
>  			vq->avail_wrap_counter ^= 1;
>  		}
>  	}
>  
> -
>  	desc[vq->vq_avail_idx].addr = cvq->virtio_net_hdr_mem
>  		+ sizeof(struct virtio_net_ctrl_hdr);
>  	desc[vq->vq_avail_idx].len = sizeof(ctrl->status);
> -	flags = VRING_DESC_F_WRITE;
> -	flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
> -		 VRING_DESC_F_USED(!vq->avail_wrap_counter);
> -	desc[vq->vq_avail_idx].flags = flags;
> -	flags = VRING_DESC_F_NEXT;
> -	flags |= VRING_DESC_F_AVAIL(avail_wrap_counter) |
> -		 VRING_DESC_F_USED(!avail_wrap_counter);
> -	desc[head].flags = flags;
> -	rte_smp_wmb();
> -

Same here. We need a write barrier to be sure that {addr, len} written
before updating flags.

Another way to avoid most of barriers is to work similar to
'flush_shadow_used_ring_packed',
i.e. update all the data in a loop - write barrier - update all the flags.

> +	desc[vq->vq_avail_idx].flags = VRING_DESC_F_WRITE |
> +		VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
> +		VRING_DESC_F_USED(!vq->avail_wrap_counter);
>  	vq->vq_free_cnt--;
> +	nb_descs++;
>  	if (++vq->vq_avail_idx >= vq->vq_nentries) {
>  		vq->vq_avail_idx -= vq->vq_nentries;
>  		vq->avail_wrap_counter ^= 1;
>  	}
>  
> +	virtio_wmb(vq->hw->weak_barriers);
> +	desc[head].flags = VRING_DESC_F_NEXT |
> +		VRING_DESC_F_AVAIL(avail_wrap_counter) |
> +		VRING_DESC_F_USED(!avail_wrap_counter);
> +
> +	virtio_wmb(vq->hw->weak_barriers);
>  	virtqueue_notify(vq);
>  
>  	/* wait for used descriptors in virtqueue */
> -	do {
> -		rte_rmb();
> +	while (!desc_is_used(&desc[head], vq))
>  		usleep(100);
> -	} while (!__desc_is_used(&desc[head], used_wrap_counter));
> +
> +	virtio_rmb(vq->hw->weak_barriers);
>  
>  	/* now get used descriptors */
> -	while (desc_is_used(&desc[vq->vq_used_cons_idx], vq)) {
> -		vq->vq_free_cnt++;
> -		if (++vq->vq_used_cons_idx >= vq->vq_nentries) {
> -			vq->vq_used_cons_idx -= vq->vq_nentries;
> -			vq->used_wrap_counter ^= 1;
> -		}
> +	vq->vq_free_cnt += nb_descs;
> +	vq->vq_used_cons_idx += nb_descs;
> +	if (vq->vq_used_cons_idx >= vq->vq_nentries) {
> +		vq->vq_used_cons_idx -= vq->vq_nentries;
> +		vq->used_wrap_counter ^= 1;
>  	}
>  
>  	result = cvq->virtio_net_hdr_mz->addr;
> @@ -266,7 +262,7 @@ virtio_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>  		sizeof(struct virtio_pmd_ctrl));
>  
>  	if (vtpci_packed_queue(vq->hw)) {
> -		result = virtio_pq_send_command(cvq, ctrl, dlen, pkt_num);
> +		result = virtio_send_command_packed(cvq, ctrl, dlen, pkt_num);
>  		goto out_unlock;
>  	}
>  
> diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
> index 7fcde5643..ca9d8e6e3 100644
> --- a/drivers/net/virtio/virtqueue.h
> +++ b/drivers/net/virtio/virtqueue.h
> @@ -281,7 +281,7 @@ struct virtio_tx_region {
>  };
>  
>  static inline int
> -__desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
> +desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
>  {
>  	uint16_t used, avail, flags;
>  
> @@ -289,16 +289,9 @@ __desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
>  	used = !!(flags & VRING_DESC_F_USED(1));
>  	avail = !!(flags & VRING_DESC_F_AVAIL(1));
>  
> -	return avail == used && used == wrap_counter;
> +	return avail == used && used == vq->used_wrap_counter;
>  }
>  
> -static inline int
> -desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
> -{
> -	return __desc_is_used(desc, vq->used_wrap_counter);
> -}
> -
> -
>  static inline void
>  vring_desc_init_packed(struct virtqueue *vq, int n)
>  {
> @@ -354,7 +347,6 @@ virtqueue_enable_intr_packed(struct virtqueue *vq)
>  {
>  	uint16_t *event_flags = &vq->ring_packed.driver_event->desc_event_flags;
>  
> -
>  	if (vq->event_flags_shadow == RING_EVENT_FLAGS_DISABLE) {
>  		virtio_wmb(vq->hw->weak_barriers);
>  		vq->event_flags_shadow = RING_EVENT_FLAGS_ENABLE;
>
Ilya Maximets Jan. 23, 2019, 4:33 p.m. UTC | #2 
Hmm. Nevermind.
Please, ignore my previous comments to this patch.
Patch seems compliant to spec, but the spec is not very clear.

Best regards, Ilya Maximets.

On 23.01.2019 16:09, Ilya Maximets wrote:
> On 22.01.2019 20:01, Tiwei Bie wrote:
>> This patch mainly fixed below issues in the packed ring based
>> control vq support in virtio driver:
>>
>> 1. When parsing the used descriptors, we have to track the
>>    number of descs that we need to skip;
>> 2. vq->vq_free_cnt was decreased twice for a same desc;
>>
>> Meanwhile, make the function name consistent with other parts.
>>
>> Fixes: ec194c2f1895 ("net/virtio: support packed queue in send command")
>> Fixes: a4270ea4ff79 ("net/virtio: check head desc with correct wrap counter")
>>
>> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
>> ---
>>  drivers/net/virtio/virtio_ethdev.c | 62 ++++++++++++++----------------
>>  drivers/net/virtio/virtqueue.h     | 12 +-----
>>  2 files changed, 31 insertions(+), 43 deletions(-)
>>
>> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
>> index ee5a98b7c..a3fe65599 100644
>> --- a/drivers/net/virtio/virtio_ethdev.c
>> +++ b/drivers/net/virtio/virtio_ethdev.c
>> @@ -142,16 +142,17 @@ static const struct rte_virtio_xstats_name_off rte_virtio_txq_stat_strings[] = {
>>  struct virtio_hw_internal virtio_hw_internal[RTE_MAX_ETHPORTS];
>>  
>>  static struct virtio_pmd_ctrl *
>> -virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>> -		       int *dlen, int pkt_num)
>> +virtio_send_command_packed(struct virtnet_ctl *cvq,
>> +			   struct virtio_pmd_ctrl *ctrl,
>> +			   int *dlen, int pkt_num)
>>  {
>>  	struct virtqueue *vq = cvq->vq;
>>  	int head;
>>  	struct vring_packed_desc *desc = vq->ring_packed.desc_packed;
>>  	struct virtio_pmd_ctrl *result;
>> -	bool avail_wrap_counter, used_wrap_counter;
>> -	uint16_t flags;
>> +	bool avail_wrap_counter;
>>  	int sum = 0;
>> +	int nb_descs = 0;
>>  	int k;
>>  
>>  	/*
>> @@ -162,11 +163,10 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>>  	 */
>>  	head = vq->vq_avail_idx;
>>  	avail_wrap_counter = vq->avail_wrap_counter;
>> -	used_wrap_counter = vq->used_wrap_counter;
>> -	desc[head].flags = VRING_DESC_F_NEXT;
>>  	desc[head].addr = cvq->virtio_net_hdr_mem;
>>  	desc[head].len = sizeof(struct virtio_net_ctrl_hdr);
>>  	vq->vq_free_cnt--;
>> +	nb_descs++;
>>  	if (++vq->vq_avail_idx >= vq->vq_nentries) {
>>  		vq->vq_avail_idx -= vq->vq_nentries;
>>  		vq->avail_wrap_counter ^= 1;
>> @@ -177,55 +177,51 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>>  			+ sizeof(struct virtio_net_ctrl_hdr)
>>  			+ sizeof(ctrl->status) + sizeof(uint8_t) * sum;
>>  		desc[vq->vq_avail_idx].len = dlen[k];
>> -		flags = VRING_DESC_F_NEXT;
> 
> Looks like barriers was badly placed here before this patch.
> Anyway, you need a write barrier here between {addr, len} and flags updates.
> 
>> +		desc[vq->vq_avail_idx].flags = VRING_DESC_F_NEXT |
>> +			VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
>> +			VRING_DESC_F_USED(!vq->avail_wrap_counter);
>>  		sum += dlen[k];
>>  		vq->vq_free_cnt--;
>> -		flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
>> -			 VRING_DESC_F_USED(!vq->avail_wrap_counter);
>> -		desc[vq->vq_avail_idx].flags = flags;
>> -		rte_smp_wmb();
>> -		vq->vq_free_cnt--;
>> +		nb_descs++;
>>  		if (++vq->vq_avail_idx >= vq->vq_nentries) {
>>  			vq->vq_avail_idx -= vq->vq_nentries;
>>  			vq->avail_wrap_counter ^= 1;
>>  		}
>>  	}
>>  
>> -
>>  	desc[vq->vq_avail_idx].addr = cvq->virtio_net_hdr_mem
>>  		+ sizeof(struct virtio_net_ctrl_hdr);
>>  	desc[vq->vq_avail_idx].len = sizeof(ctrl->status);
>> -	flags = VRING_DESC_F_WRITE;
>> -	flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
>> -		 VRING_DESC_F_USED(!vq->avail_wrap_counter);
>> -	desc[vq->vq_avail_idx].flags = flags;
>> -	flags = VRING_DESC_F_NEXT;
>> -	flags |= VRING_DESC_F_AVAIL(avail_wrap_counter) |
>> -		 VRING_DESC_F_USED(!avail_wrap_counter);
>> -	desc[head].flags = flags;
>> -	rte_smp_wmb();
>> -
> 
> Same here. We need a write barrier to be sure that {addr, len} written
> before updating flags.
> 
> Another way to avoid most of barriers is to work similar to
> 'flush_shadow_used_ring_packed',
> i.e. update all the data in a loop - write barrier - update all the flags.
> 
>> +	desc[vq->vq_avail_idx].flags = VRING_DESC_F_WRITE |
>> +		VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
>> +		VRING_DESC_F_USED(!vq->avail_wrap_counter);
>>  	vq->vq_free_cnt--;
>> +	nb_descs++;
>>  	if (++vq->vq_avail_idx >= vq->vq_nentries) {
>>  		vq->vq_avail_idx -= vq->vq_nentries;
>>  		vq->avail_wrap_counter ^= 1;
>>  	}
>>  
>> +	virtio_wmb(vq->hw->weak_barriers);
>> +	desc[head].flags = VRING_DESC_F_NEXT |
>> +		VRING_DESC_F_AVAIL(avail_wrap_counter) |
>> +		VRING_DESC_F_USED(!avail_wrap_counter);
>> +
>> +	virtio_wmb(vq->hw->weak_barriers);
>>  	virtqueue_notify(vq);
>>  
>>  	/* wait for used descriptors in virtqueue */
>> -	do {
>> -		rte_rmb();
>> +	while (!desc_is_used(&desc[head], vq))
>>  		usleep(100);
>> -	} while (!__desc_is_used(&desc[head], used_wrap_counter));
>> +
>> +	virtio_rmb(vq->hw->weak_barriers);
>>  
>>  	/* now get used descriptors */
>> -	while (desc_is_used(&desc[vq->vq_used_cons_idx], vq)) {
>> -		vq->vq_free_cnt++;
>> -		if (++vq->vq_used_cons_idx >= vq->vq_nentries) {
>> -			vq->vq_used_cons_idx -= vq->vq_nentries;
>> -			vq->used_wrap_counter ^= 1;
>> -		}
>> +	vq->vq_free_cnt += nb_descs;
>> +	vq->vq_used_cons_idx += nb_descs;
>> +	if (vq->vq_used_cons_idx >= vq->vq_nentries) {
>> +		vq->vq_used_cons_idx -= vq->vq_nentries;
>> +		vq->used_wrap_counter ^= 1;
>>  	}
>>  
>>  	result = cvq->virtio_net_hdr_mz->addr;
>> @@ -266,7 +262,7 @@ virtio_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>>  		sizeof(struct virtio_pmd_ctrl));
>>  
>>  	if (vtpci_packed_queue(vq->hw)) {
>> -		result = virtio_pq_send_command(cvq, ctrl, dlen, pkt_num);
>> +		result = virtio_send_command_packed(cvq, ctrl, dlen, pkt_num);
>>  		goto out_unlock;
>>  	}
>>  
>> diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
>> index 7fcde5643..ca9d8e6e3 100644
>> --- a/drivers/net/virtio/virtqueue.h
>> +++ b/drivers/net/virtio/virtqueue.h
>> @@ -281,7 +281,7 @@ struct virtio_tx_region {
>>  };
>>  
>>  static inline int
>> -__desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
>> +desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
>>  {
>>  	uint16_t used, avail, flags;
>>  
>> @@ -289,16 +289,9 @@ __desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
>>  	used = !!(flags & VRING_DESC_F_USED(1));
>>  	avail = !!(flags & VRING_DESC_F_AVAIL(1));
>>  
>> -	return avail == used && used == wrap_counter;
>> +	return avail == used && used == vq->used_wrap_counter;
>>  }
>>  
>> -static inline int
>> -desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
>> -{
>> -	return __desc_is_used(desc, vq->used_wrap_counter);
>> -}
>> -
>> -
>>  static inline void
>>  vring_desc_init_packed(struct virtqueue *vq, int n)
>>  {
>> @@ -354,7 +347,6 @@ virtqueue_enable_intr_packed(struct virtqueue *vq)
>>  {
>>  	uint16_t *event_flags = &vq->ring_packed.driver_event->desc_event_flags;
>>  
>> -
>>  	if (vq->event_flags_shadow == RING_EVENT_FLAGS_DISABLE) {
>>  		virtio_wmb(vq->hw->weak_barriers);
>>  		vq->event_flags_shadow = RING_EVENT_FLAGS_ENABLE;
>>
Maxime Coquelin Jan. 23, 2019, 10:02 p.m. UTC | #3 
On 1/23/19 5:33 PM, Ilya Maximets wrote:
> Hmm. Nevermind.
> Please, ignore my previous comments to this patch.
> Patch seems compliant to spec, but the spec is not very clear.

Ok, thanks for the review and the folluw-up.

Maxime

> Best regards, Ilya Maximets.
> 
> On 23.01.2019 16:09, Ilya Maximets wrote:
>> On 22.01.2019 20:01, Tiwei Bie wrote:
>>> This patch mainly fixed below issues in the packed ring based
>>> control vq support in virtio driver:
>>>
>>> 1. When parsing the used descriptors, we have to track the
>>>     number of descs that we need to skip;
>>> 2. vq->vq_free_cnt was decreased twice for a same desc;
>>>
>>> Meanwhile, make the function name consistent with other parts.
>>>
>>> Fixes: ec194c2f1895 ("net/virtio: support packed queue in send command")
>>> Fixes: a4270ea4ff79 ("net/virtio: check head desc with correct wrap counter")
>>>
>>> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
>>> ---
>>>   drivers/net/virtio/virtio_ethdev.c | 62 ++++++++++++++----------------
>>>   drivers/net/virtio/virtqueue.h     | 12 +-----
>>>   2 files changed, 31 insertions(+), 43 deletions(-)
>>>
>>> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
>>> index ee5a98b7c..a3fe65599 100644
>>> --- a/drivers/net/virtio/virtio_ethdev.c
>>> +++ b/drivers/net/virtio/virtio_ethdev.c
>>> @@ -142,16 +142,17 @@ static const struct rte_virtio_xstats_name_off rte_virtio_txq_stat_strings[] = {
>>>   struct virtio_hw_internal virtio_hw_internal[RTE_MAX_ETHPORTS];
>>>   
>>>   static struct virtio_pmd_ctrl *
>>> -virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>>> -		       int *dlen, int pkt_num)
>>> +virtio_send_command_packed(struct virtnet_ctl *cvq,
>>> +			   struct virtio_pmd_ctrl *ctrl,
>>> +			   int *dlen, int pkt_num)
>>>   {
>>>   	struct virtqueue *vq = cvq->vq;
>>>   	int head;
>>>   	struct vring_packed_desc *desc = vq->ring_packed.desc_packed;
>>>   	struct virtio_pmd_ctrl *result;
>>> -	bool avail_wrap_counter, used_wrap_counter;
>>> -	uint16_t flags;
>>> +	bool avail_wrap_counter;
>>>   	int sum = 0;
>>> +	int nb_descs = 0;
>>>   	int k;
>>>   
>>>   	/*
>>> @@ -162,11 +163,10 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>>>   	 */
>>>   	head = vq->vq_avail_idx;
>>>   	avail_wrap_counter = vq->avail_wrap_counter;
>>> -	used_wrap_counter = vq->used_wrap_counter;
>>> -	desc[head].flags = VRING_DESC_F_NEXT;
>>>   	desc[head].addr = cvq->virtio_net_hdr_mem;
>>>   	desc[head].len = sizeof(struct virtio_net_ctrl_hdr);
>>>   	vq->vq_free_cnt--;
>>> +	nb_descs++;
>>>   	if (++vq->vq_avail_idx >= vq->vq_nentries) {
>>>   		vq->vq_avail_idx -= vq->vq_nentries;
>>>   		vq->avail_wrap_counter ^= 1;
>>> @@ -177,55 +177,51 @@ virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>>>   			+ sizeof(struct virtio_net_ctrl_hdr)
>>>   			+ sizeof(ctrl->status) + sizeof(uint8_t) * sum;
>>>   		desc[vq->vq_avail_idx].len = dlen[k];
>>> -		flags = VRING_DESC_F_NEXT;
>>
>> Looks like barriers was badly placed here before this patch.
>> Anyway, you need a write barrier here between {addr, len} and flags updates.
>>
>>> +		desc[vq->vq_avail_idx].flags = VRING_DESC_F_NEXT |
>>> +			VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
>>> +			VRING_DESC_F_USED(!vq->avail_wrap_counter);
>>>   		sum += dlen[k];
>>>   		vq->vq_free_cnt--;
>>> -		flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
>>> -			 VRING_DESC_F_USED(!vq->avail_wrap_counter);
>>> -		desc[vq->vq_avail_idx].flags = flags;
>>> -		rte_smp_wmb();
>>> -		vq->vq_free_cnt--;
>>> +		nb_descs++;
>>>   		if (++vq->vq_avail_idx >= vq->vq_nentries) {
>>>   			vq->vq_avail_idx -= vq->vq_nentries;
>>>   			vq->avail_wrap_counter ^= 1;
>>>   		}
>>>   	}
>>>   
>>> -
>>>   	desc[vq->vq_avail_idx].addr = cvq->virtio_net_hdr_mem
>>>   		+ sizeof(struct virtio_net_ctrl_hdr);
>>>   	desc[vq->vq_avail_idx].len = sizeof(ctrl->status);
>>> -	flags = VRING_DESC_F_WRITE;
>>> -	flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
>>> -		 VRING_DESC_F_USED(!vq->avail_wrap_counter);
>>> -	desc[vq->vq_avail_idx].flags = flags;
>>> -	flags = VRING_DESC_F_NEXT;
>>> -	flags |= VRING_DESC_F_AVAIL(avail_wrap_counter) |
>>> -		 VRING_DESC_F_USED(!avail_wrap_counter);
>>> -	desc[head].flags = flags;
>>> -	rte_smp_wmb();
>>> -
>>
>> Same here. We need a write barrier to be sure that {addr, len} written
>> before updating flags.
>>
>> Another way to avoid most of barriers is to work similar to
>> 'flush_shadow_used_ring_packed',
>> i.e. update all the data in a loop - write barrier - update all the flags.
>>
>>> +	desc[vq->vq_avail_idx].flags = VRING_DESC_F_WRITE |
>>> +		VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
>>> +		VRING_DESC_F_USED(!vq->avail_wrap_counter);
>>>   	vq->vq_free_cnt--;
>>> +	nb_descs++;
>>>   	if (++vq->vq_avail_idx >= vq->vq_nentries) {
>>>   		vq->vq_avail_idx -= vq->vq_nentries;
>>>   		vq->avail_wrap_counter ^= 1;
>>>   	}
>>>   
>>> +	virtio_wmb(vq->hw->weak_barriers);
>>> +	desc[head].flags = VRING_DESC_F_NEXT |
>>> +		VRING_DESC_F_AVAIL(avail_wrap_counter) |
>>> +		VRING_DESC_F_USED(!avail_wrap_counter);
>>> +
>>> +	virtio_wmb(vq->hw->weak_barriers);
>>>   	virtqueue_notify(vq);
>>>   
>>>   	/* wait for used descriptors in virtqueue */
>>> -	do {
>>> -		rte_rmb();
>>> +	while (!desc_is_used(&desc[head], vq))
>>>   		usleep(100);
>>> -	} while (!__desc_is_used(&desc[head], used_wrap_counter));
>>> +
>>> +	virtio_rmb(vq->hw->weak_barriers);
>>>   
>>>   	/* now get used descriptors */
>>> -	while (desc_is_used(&desc[vq->vq_used_cons_idx], vq)) {
>>> -		vq->vq_free_cnt++;
>>> -		if (++vq->vq_used_cons_idx >= vq->vq_nentries) {
>>> -			vq->vq_used_cons_idx -= vq->vq_nentries;
>>> -			vq->used_wrap_counter ^= 1;
>>> -		}
>>> +	vq->vq_free_cnt += nb_descs;
>>> +	vq->vq_used_cons_idx += nb_descs;
>>> +	if (vq->vq_used_cons_idx >= vq->vq_nentries) {
>>> +		vq->vq_used_cons_idx -= vq->vq_nentries;
>>> +		vq->used_wrap_counter ^= 1;
>>>   	}
>>>   
>>>   	result = cvq->virtio_net_hdr_mz->addr;
>>> @@ -266,7 +262,7 @@ virtio_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
>>>   		sizeof(struct virtio_pmd_ctrl));
>>>   
>>>   	if (vtpci_packed_queue(vq->hw)) {
>>> -		result = virtio_pq_send_command(cvq, ctrl, dlen, pkt_num);
>>> +		result = virtio_send_command_packed(cvq, ctrl, dlen, pkt_num);
>>>   		goto out_unlock;
>>>   	}
>>>   
>>> diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
>>> index 7fcde5643..ca9d8e6e3 100644
>>> --- a/drivers/net/virtio/virtqueue.h
>>> +++ b/drivers/net/virtio/virtqueue.h
>>> @@ -281,7 +281,7 @@ struct virtio_tx_region {
>>>   };
>>>   
>>>   static inline int
>>> -__desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
>>> +desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
>>>   {
>>>   	uint16_t used, avail, flags;
>>>   
>>> @@ -289,16 +289,9 @@ __desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
>>>   	used = !!(flags & VRING_DESC_F_USED(1));
>>>   	avail = !!(flags & VRING_DESC_F_AVAIL(1));
>>>   
>>> -	return avail == used && used == wrap_counter;
>>> +	return avail == used && used == vq->used_wrap_counter;
>>>   }
>>>   
>>> -static inline int
>>> -desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
>>> -{
>>> -	return __desc_is_used(desc, vq->used_wrap_counter);
>>> -}
>>> -
>>> -
>>>   static inline void
>>>   vring_desc_init_packed(struct virtqueue *vq, int n)
>>>   {
>>> @@ -354,7 +347,6 @@ virtqueue_enable_intr_packed(struct virtqueue *vq)
>>>   {
>>>   	uint16_t *event_flags = &vq->ring_packed.driver_event->desc_event_flags;
>>>   
>>> -
>>>   	if (vq->event_flags_shadow == RING_EVENT_FLAGS_DISABLE) {
>>>   		virtio_wmb(vq->hw->weak_barriers);
>>>   		vq->event_flags_shadow = RING_EVENT_FLAGS_ENABLE;
>>>
Maxime Coquelin Jan. 23, 2019, 10:03 p.m. UTC | #4 
On 1/22/19 6:01 PM, Tiwei Bie wrote:
> This patch mainly fixed below issues in the packed ring based
> control vq support in virtio driver:
> 
> 1. When parsing the used descriptors, we have to track the
>     number of descs that we need to skip;
> 2. vq->vq_free_cnt was decreased twice for a same desc;
> 
> Meanwhile, make the function name consistent with other parts.
> 
> Fixes: ec194c2f1895 ("net/virtio: support packed queue in send command")
> Fixes: a4270ea4ff79 ("net/virtio: check head desc with correct wrap counter")
> 
> Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>
> ---
>   drivers/net/virtio/virtio_ethdev.c | 62 ++++++++++++++----------------
>   drivers/net/virtio/virtqueue.h     | 12 +-----
>   2 files changed, 31 insertions(+), 43 deletions(-)
> 

Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Thanks,
Maxime
diff mbox series

Patch

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index ee5a98b7c..a3fe65599 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -142,16 +142,17 @@  static const struct rte_virtio_xstats_name_off rte_virtio_txq_stat_strings[] = {
 struct virtio_hw_internal virtio_hw_internal[RTE_MAX_ETHPORTS];
 
 static struct virtio_pmd_ctrl *
-virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
-		       int *dlen, int pkt_num)
+virtio_send_command_packed(struct virtnet_ctl *cvq,
+			   struct virtio_pmd_ctrl *ctrl,
+			   int *dlen, int pkt_num)
 {
 	struct virtqueue *vq = cvq->vq;
 	int head;
 	struct vring_packed_desc *desc = vq->ring_packed.desc_packed;
 	struct virtio_pmd_ctrl *result;
-	bool avail_wrap_counter, used_wrap_counter;
-	uint16_t flags;
+	bool avail_wrap_counter;
 	int sum = 0;
+	int nb_descs = 0;
 	int k;
 
 	/*
@@ -162,11 +163,10 @@  virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
 	 */
 	head = vq->vq_avail_idx;
 	avail_wrap_counter = vq->avail_wrap_counter;
-	used_wrap_counter = vq->used_wrap_counter;
-	desc[head].flags = VRING_DESC_F_NEXT;
 	desc[head].addr = cvq->virtio_net_hdr_mem;
 	desc[head].len = sizeof(struct virtio_net_ctrl_hdr);
 	vq->vq_free_cnt--;
+	nb_descs++;
 	if (++vq->vq_avail_idx >= vq->vq_nentries) {
 		vq->vq_avail_idx -= vq->vq_nentries;
 		vq->avail_wrap_counter ^= 1;
@@ -177,55 +177,51 @@  virtio_pq_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
 			+ sizeof(struct virtio_net_ctrl_hdr)
 			+ sizeof(ctrl->status) + sizeof(uint8_t) * sum;
 		desc[vq->vq_avail_idx].len = dlen[k];
-		flags = VRING_DESC_F_NEXT;
+		desc[vq->vq_avail_idx].flags = VRING_DESC_F_NEXT |
+			VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
+			VRING_DESC_F_USED(!vq->avail_wrap_counter);
 		sum += dlen[k];
 		vq->vq_free_cnt--;
-		flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
-			 VRING_DESC_F_USED(!vq->avail_wrap_counter);
-		desc[vq->vq_avail_idx].flags = flags;
-		rte_smp_wmb();
-		vq->vq_free_cnt--;
+		nb_descs++;
 		if (++vq->vq_avail_idx >= vq->vq_nentries) {
 			vq->vq_avail_idx -= vq->vq_nentries;
 			vq->avail_wrap_counter ^= 1;
 		}
 	}
 
-
 	desc[vq->vq_avail_idx].addr = cvq->virtio_net_hdr_mem
 		+ sizeof(struct virtio_net_ctrl_hdr);
 	desc[vq->vq_avail_idx].len = sizeof(ctrl->status);
-	flags = VRING_DESC_F_WRITE;
-	flags |= VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
-		 VRING_DESC_F_USED(!vq->avail_wrap_counter);
-	desc[vq->vq_avail_idx].flags = flags;
-	flags = VRING_DESC_F_NEXT;
-	flags |= VRING_DESC_F_AVAIL(avail_wrap_counter) |
-		 VRING_DESC_F_USED(!avail_wrap_counter);
-	desc[head].flags = flags;
-	rte_smp_wmb();
-
+	desc[vq->vq_avail_idx].flags = VRING_DESC_F_WRITE |
+		VRING_DESC_F_AVAIL(vq->avail_wrap_counter) |
+		VRING_DESC_F_USED(!vq->avail_wrap_counter);
 	vq->vq_free_cnt--;
+	nb_descs++;
 	if (++vq->vq_avail_idx >= vq->vq_nentries) {
 		vq->vq_avail_idx -= vq->vq_nentries;
 		vq->avail_wrap_counter ^= 1;
 	}
 
+	virtio_wmb(vq->hw->weak_barriers);
+	desc[head].flags = VRING_DESC_F_NEXT |
+		VRING_DESC_F_AVAIL(avail_wrap_counter) |
+		VRING_DESC_F_USED(!avail_wrap_counter);
+
+	virtio_wmb(vq->hw->weak_barriers);
 	virtqueue_notify(vq);
 
 	/* wait for used descriptors in virtqueue */
-	do {
-		rte_rmb();
+	while (!desc_is_used(&desc[head], vq))
 		usleep(100);
-	} while (!__desc_is_used(&desc[head], used_wrap_counter));
+
+	virtio_rmb(vq->hw->weak_barriers);
 
 	/* now get used descriptors */
-	while (desc_is_used(&desc[vq->vq_used_cons_idx], vq)) {
-		vq->vq_free_cnt++;
-		if (++vq->vq_used_cons_idx >= vq->vq_nentries) {
-			vq->vq_used_cons_idx -= vq->vq_nentries;
-			vq->used_wrap_counter ^= 1;
-		}
+	vq->vq_free_cnt += nb_descs;
+	vq->vq_used_cons_idx += nb_descs;
+	if (vq->vq_used_cons_idx >= vq->vq_nentries) {
+		vq->vq_used_cons_idx -= vq->vq_nentries;
+		vq->used_wrap_counter ^= 1;
 	}
 
 	result = cvq->virtio_net_hdr_mz->addr;
@@ -266,7 +262,7 @@  virtio_send_command(struct virtnet_ctl *cvq, struct virtio_pmd_ctrl *ctrl,
 		sizeof(struct virtio_pmd_ctrl));
 
 	if (vtpci_packed_queue(vq->hw)) {
-		result = virtio_pq_send_command(cvq, ctrl, dlen, pkt_num);
+		result = virtio_send_command_packed(cvq, ctrl, dlen, pkt_num);
 		goto out_unlock;
 	}
 
diff --git a/drivers/net/virtio/virtqueue.h b/drivers/net/virtio/virtqueue.h
index 7fcde5643..ca9d8e6e3 100644
--- a/drivers/net/virtio/virtqueue.h
+++ b/drivers/net/virtio/virtqueue.h
@@ -281,7 +281,7 @@  struct virtio_tx_region {
 };
 
 static inline int
-__desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
+desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
 {
 	uint16_t used, avail, flags;
 
@@ -289,16 +289,9 @@  __desc_is_used(struct vring_packed_desc *desc, bool wrap_counter)
 	used = !!(flags & VRING_DESC_F_USED(1));
 	avail = !!(flags & VRING_DESC_F_AVAIL(1));
 
-	return avail == used && used == wrap_counter;
+	return avail == used && used == vq->used_wrap_counter;
 }
 
-static inline int
-desc_is_used(struct vring_packed_desc *desc, struct virtqueue *vq)
-{
-	return __desc_is_used(desc, vq->used_wrap_counter);
-}
-
-
 static inline void
 vring_desc_init_packed(struct virtqueue *vq, int n)
 {
@@ -354,7 +347,6 @@  virtqueue_enable_intr_packed(struct virtqueue *vq)
 {
 	uint16_t *event_flags = &vq->ring_packed.driver_event->desc_event_flags;
 
-
 	if (vq->event_flags_shadow == RING_EVENT_FLAGS_DISABLE) {
 		virtio_wmb(vq->hw->weak_barriers);
 		vq->event_flags_shadow = RING_EVENT_FLAGS_ENABLE;