[dpdk-dev,v2] vhost: Fix default value of kickfd and callfd
Commit Message
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.
Signed-off-by: Tetsuya Mukawa <mukawa@igel.co.jp>
---
lib/librte_vhost/rte_virtio_net.h | 1 +
lib/librte_vhost/vhost_user/virtio-net-user.c | 10 +++++-----
lib/librte_vhost/virtio-net.c | 4 ++--
3 files changed, 8 insertions(+), 7 deletions(-)
Comments
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. Besides, this patch would make
following fail:
eventfd_write(vq->callfd, (eventfd_t)1);
--yliu
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?
> 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
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.
--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
@@ -89,6 +89,7 @@ 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)
int callfd; /**< Used to notify the guest (trigger interrupt). */
int kickfd; /**< Currently unused as polling mode is enabled. */
int enabled;
@@ -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
@@ -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;
}
@@ -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;