On 2016/03/14 11:08, Yuanhan Liu wrote:
> On Mon, Mar 14, 2016 at 10:54:14AM +0900, Tetsuya Mukawa wrote:
>> On 2016/03/11 16:19, Yuanhan Liu wrote:
>>> On Thu, Mar 10, 2016 at 04:06:05PM +0900, Tetsuya Mukawa wrote:
>>>> Currently, default values of kickfd and callfd are -1.
>>>> If the values are -1, current code guesses kickfd and callfd haven't
>>>> been initialized yet. And vhost library will guess the virtqueue isn't
>>>> ready for processing.
>>>> But callfd and kickfd will be set as -1 when "--enable-kvm"
>>>> isn't specified in QEMU command line. It means we cannot treat -1 as
>>>> uninitialized state. The patch changes default values to -2. And the
>>>> patch defines -2 as VIRTIO_UNINITIALIZED_EVENTFD.
>>> This looks more like a workaround to me.
>>
>> Hi Yuanhan,
>>
>> Sorry for late reply.
>> I have checked QEMU documentation, and found below.
>>
>> ----------
>> * VHOST_USER_SET_VRING_CALL
>>
>> Id: 14
>> Equivalent ioctl: VHOST_SET_VRING_CALL
>> Master payload: u64
>>
>> Set the event file descriptor to signal when buffers are used. It
>> is passed in the ancillary data.
>> Bits (0-7) of the payload contain the vring index. Bit 8 is the
>> invalid FD flag.
>> ----------
>>
>> VHOST_USER_SET_VRING_KICK has almost same description.
>> I will check this invalid flag, and if it works for our case, then will
>> use it.
>> How about it?
> Yeah, that indeed sounds much better.
I've checked current dpdk code.
It seems we've already checked invalid flag like below.
if (pmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
file.fd = -1;
else
file.fd = pmsg->fds[0];
So how about adding below macros or enum?
#define VIRTIO_UNINITIALIZED_EVENTFD (-2)
#define VIRTIO_INVALID_EVENTFD (-1)
I am still not sure whether using enum is better or not.
But here is one of example patch.
What do you think?
diff --git a/lib/librte_vhost/rte_virtio_net.h
b/lib/librte_vhost/rte_virtio_net.h
index 7d1fde2..2a7566d 100644
--- a/lib/librte_vhost/rte_virtio_net.h
+++ b/lib/librte_vhost/rte_virtio_net.h
@@ -89,6 +89,8 @@ struct vhost_virtqueue {
uint16_t vhost_hlen; /**< Vhost
header length (varies depending on RX merge buffers. */
volatile uint16_t last_used_idx; /**< Last index
used on the available ring */
volatile uint16_t last_used_idx_res; /**< Used for
multiple devices reserving buffers. */
+#define VIRTIO_UNINITIALIZED_EVENTFD (-2)
+#define VIRTIO_INVALID_EVENTFD (-1)
int callfd; /**< Used to
notify the guest (trigger interrupt). */
int kickfd; /**< Currently
unused as polling mode is enabled. */
int enabled;
diff --git a/lib/librte_vhost/vhost_rxtx.c b/lib/librte_vhost/vhost_rxtx.c
index 9d23eb1..29d002d 100644
--- a/lib/librte_vhost/vhost_rxtx.c
+++ b/lib/librte_vhost/vhost_rxtx.c
@@ -333,7 +333,8 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
rte_mb();
/* Kick the guest if necessary. */
- if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+ if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+ && (vq->callfd >= 0))
eventfd_write(vq->callfd, (eventfd_t)1);
return count;
}
@@ -654,7 +655,8 @@ merge_rx_exit:
rte_mb();
/* Kick the guest if necessary. */
- if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+ if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+ && (vq->callfd >= 0))
eventfd_write(vq->callfd, (eventfd_t)1);
}
@@ -1048,7 +1050,8 @@ rte_vhost_dequeue_burst(struct virtio_net *dev,
uint16_t queue_id,
sizeof(vq->used->idx));
/* Kick guest if required. */
- if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT))
+ if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+ && (vq->callfd >= 0))
eventfd_write(vq->callfd, (eventfd_t)1);
out:
diff --git a/lib/librte_vhost/vhost_user/virtio-net-user.c
b/lib/librte_vhost/vhost_user/virtio-net-user.c
index 65b5652..f5248bc 100644
--- a/lib/librte_vhost/vhost_user/virtio-net-user.c
+++ b/lib/librte_vhost/vhost_user/virtio-net-user.c
@@ -225,8 +225,8 @@ static int
vq_is_ready(struct vhost_virtqueue *vq)
{
return vq && vq->desc &&
- vq->kickfd != -1 &&
- vq->callfd != -1;
+ vq->kickfd != VIRTIO_UNINITIALIZED_EVENTFD &&
+ vq->callfd != VIRTIO_UNINITIALIZED_EVENTFD;
}
static int
@@ -258,7 +258,7 @@ user_set_vring_call(struct vhost_device_ctx ctx,
struct VhostUserMsg *pmsg)
file.index = pmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
if (pmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
- file.fd = -1;
+ file.fd = VIRTIO_INVALID_EVENTFD;
else
file.fd = pmsg->fds[0];
RTE_LOG(INFO, VHOST_CONFIG,
@@ -279,7 +279,7 @@ user_set_vring_kick(struct vhost_device_ctx ctx,
struct VhostUserMsg *pmsg)
file.index = pmsg->payload.u64 & VHOST_USER_VRING_IDX_MASK;
if (pmsg->payload.u64 & VHOST_USER_VRING_NOFD_MASK)
- file.fd = -1;
+ file.fd = VIRTIO_INVALID_EVENTFD;
else
file.fd = pmsg->fds[0];
RTE_LOG(INFO, VHOST_CONFIG,
@@ -316,10 +316,10 @@ user_get_vring_base(struct vhost_device_ctx ctx,
* sent and only sent in vhost_vring_stop.
* TODO: cleanup the vring, it isn't usable since here.
*/
- if (dev->virtqueue[state->index]->kickfd >= 0) {
+ if (dev->virtqueue[state->index]->kickfd >= 0)
close(dev->virtqueue[state->index]->kickfd);
- dev->virtqueue[state->index]->kickfd = -1;
- }
+
+ dev->virtqueue[state->index]->kickfd = VIRTIO_UNINITIALIZED_EVENTFD;
return 0;
}
diff --git a/lib/librte_vhost/virtio-net.c b/lib/librte_vhost/virtio-net.c
index fe1a77e..3498e9d 100644
--- a/lib/librte_vhost/virtio-net.c
+++ b/lib/librte_vhost/virtio-net.c
@@ -263,8 +263,8 @@ init_vring_queue(struct vhost_virtqueue *vq, int qp_idx)
{
memset(vq, 0, sizeof(struct vhost_virtqueue));
- vq->kickfd = -1;
- vq->callfd = -1;
+ vq->kickfd = VIRTIO_UNINITIALIZED_EVENTFD;
+ vq->callfd = VIRTIO_UNINITIALIZED_EVENTFD;
/* Backends are set to -1 indicating an inactive device. */
vq->backend = -1;
> --yliu
>
>>> Besides, this patch would make
>>> following fail:
>>>
>>> eventfd_write(vq->callfd, (eventfd_t)1);
>> It's my fault.
>> I thought above case should be blocked by virtio spec itself. So just
>> leave it.
>> But eventfd is came from vhost spec, so VRING_AVAIL_F_NO_INTERRUPT might
>> be set even when kickfd and callfd are -1.
>> Thanks for checking it.
>>
>> Tetsuya
>>
>>> --yliu
