[dpdk-dev,v6] vhost: support virtqueue interrupt/notification suppression
Checks
Commit Message
The driver can suppress interrupt when VIRTIO_F_EVENT_IDX feature bit is
negotiated. The driver set vring flags to 0, and MAY use used_event in
available ring to advise device interrupt util reach an index specified
by used_event. The device ignore the lower bit of vring flags, and send
an interrupt when index reach used_event.
The device can suppress notification in a manner analogous to the ways
driver suppress interrupt. The device manipulates flags or avail_event in
the used ring in the same way the driver manipulates flags or used_event in
available ring.
This patch is to enable this feature in vhost.
Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
v6:
Use volatile qualifier to access avail event idx.
v5:
Remove updating avail event index in backend.
v2-v4:
Use definition of VIRTIO_F_EVENT_IDX from kernel.
---
lib/librte_vhost/vhost.h | 3 +++
lib/librte_vhost/virtio_net.c | 46 +++++++++++++++++++++++++++++--------------
2 files changed, 34 insertions(+), 15 deletions(-)
Comments
Hi,
> -----Original Message-----
> From: Chen, Junjie J
> Sent: Wednesday, December 27, 2017 1:43 AM
> To: Wang, Xiao W <xiao.w.wang@intel.com>; yliu@fridaylinux.org;
> maxime.coquelin@redhat.com; Bie, Tiwei <tiwei.bie@intel.com>
> Cc: dev@dpdk.org; Chen, Junjie J <junjie.j.chen@intel.com>
> Subject: [PATCH v6] vhost: support virtqueue interrupt/notification
> suppression
>
> The driver can suppress interrupt when VIRTIO_F_EVENT_IDX feature bit is
> negotiated. The driver set vring flags to 0, and MAY use used_event in
> available ring to advise device interrupt util reach an index specified
> by used_event. The device ignore the lower bit of vring flags, and send
> an interrupt when index reach used_event.
>
> The device can suppress notification in a manner analogous to the ways
> driver suppress interrupt. The device manipulates flags or avail_event in
> the used ring in the same way the driver manipulates flags or used_event in
> available ring.
>
> This patch is to enable this feature in vhost.
>
> Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
>
> v6:
> Use volatile qualifier to access avail event idx.
>
> v5:
> Remove updating avail event index in backend.
>
> v2-v4:
> Use definition of VIRTIO_F_EVENT_IDX from kernel.
>
> ---
> lib/librte_vhost/vhost.h | 3 +++
> lib/librte_vhost/virtio_net.c | 46 +++++++++++++++++++++++++++++-------------
> -
> 2 files changed, 34 insertions(+), 15 deletions(-)
>
> diff --git a/lib/librte_vhost/vhost.h b/lib/librte_vhost/vhost.h
> index 1cc81c1..fc41c20 100644
> --- a/lib/librte_vhost/vhost.h
> +++ b/lib/librte_vhost/vhost.h
> @@ -103,6 +103,8 @@ struct vhost_virtqueue {
>
> uint16_t last_avail_idx;
> uint16_t last_used_idx;
> + /* Last used index we notify to front end. */
> + uint16_t signalled_used;
> #define VIRTIO_INVALID_EVENTFD (-1)
> #define VIRTIO_UNINITIALIZED_EVENTFD (-2)
>
> @@ -211,6 +213,7 @@ struct vhost_msg {
> (1ULL << VIRTIO_NET_F_GUEST_TSO4) | \
> (1ULL << VIRTIO_NET_F_GUEST_TSO6) | \
> (1ULL << VIRTIO_RING_F_INDIRECT_DESC) | \
> + (1ULL << VIRTIO_RING_F_EVENT_IDX) | \
> (1ULL << VIRTIO_NET_F_MTU) | \
> (1ULL << VIRTIO_F_IOMMU_PLATFORM))
>
> diff --git a/lib/librte_vhost/virtio_net.c b/lib/librte_vhost/virtio_net.c
> index 6fee16e..f5777fc 100644
> --- a/lib/librte_vhost/virtio_net.c
> +++ b/lib/librte_vhost/virtio_net.c
> @@ -52,6 +52,34 @@
>
> #define MAX_BATCH_LEN 256
>
> +#define vhost_used_event(vr) \
> + (*(volatile uint16_t*)&(vr)->avail->ring[(vr)->size])
> +
> +static __rte_always_inline void
> +vhost_notify(struct virtio_net *dev, struct vhost_virtqueue *vq)
> +{
> + /* Don't notify guest if we don't reach index specified by guest. */
> + if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) {
> + uint16_t old = vq->signalled_used;
> + uint16_t new = vq->last_used_idx;
> +
> + LOG_DEBUG(VHOST_DATA, "%s: used_event_idx=%d, old=%d,
> new=%d\n",
> + __func__,
> + vhost_used_event(vq),
> + old, new);
> + if (vring_need_event(vhost_used_event(vq), new, old)
> + && (vq->callfd >= 0)) {
> + vq->signalled_used = vq->last_used_idx;
> + eventfd_write(vq->callfd, (eventfd_t) 1);
> + }
> + } else {
> + /* Kick the guest if necessary. */
> + if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
> + && (vq->callfd >= 0))
> + eventfd_write(vq->callfd, (eventfd_t)1);
> + }
> +}
> +
> static bool
> is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t nr_vring)
> {
> @@ -410,11 +438,7 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t
> queue_id,
>
> /* flush used->idx update before we read avail->flags. */
> rte_mb();
> -
> - /* Kick the guest if necessary. */
> - if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
> - && (vq->callfd >= 0))
> - eventfd_write(vq->callfd, (eventfd_t)1);
> + vhost_notify(dev, vq);
> out:
> if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
> vhost_user_iotlb_rd_unlock(vq);
> @@ -704,11 +728,7 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t
> queue_id,
>
> /* flush used->idx update before we read avail->flags. */
> rte_mb();
> -
> - /* Kick the guest if necessary. */
> - if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
> - && (vq->callfd >= 0))
> - eventfd_write(vq->callfd, (eventfd_t)1);
> + vhost_notify(dev, vq);
> }
>
> out:
> @@ -1106,11 +1126,7 @@ update_used_idx(struct virtio_net *dev, struct
> vhost_virtqueue *vq,
> vq->used->idx += count;
> vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
> sizeof(vq->used->idx));
> -
> - /* Kick guest if required. */
> - if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
> - && (vq->callfd >= 0))
> - eventfd_write(vq->callfd, (eventfd_t)1);
> + vhost_notify(dev, vq);
> }
>
> static __rte_always_inline struct zcopy_mbuf *
> --
> 2.0.1
Reviewed-by: Xiao Wang <xiao.w.wang@intel.com>
On Tue, Dec 26, 2017 at 12:43:10PM -0500, Junjie Chen wrote:
> The driver can suppress interrupt when VIRTIO_F_EVENT_IDX feature bit is
> negotiated. The driver set vring flags to 0, and MAY use used_event in
> available ring to advise device interrupt util reach an index specified
> by used_event. The device ignore the lower bit of vring flags, and send
> an interrupt when index reach used_event.
>
> The device can suppress notification in a manner analogous to the ways
> driver suppress interrupt. The device manipulates flags or avail_event in
> the used ring in the same way the driver manipulates flags or used_event in
> available ring.
>
> This patch is to enable this feature in vhost.
>
> Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
You need put "---" before the change log. Otherwise, it will be tracked in
the commit log.
> +#define vhost_used_event(vr) \
> + (*(volatile uint16_t*)&(vr)->avail->ring[(vr)->size])
> +
> +static __rte_always_inline void
> +vhost_notify(struct virtio_net *dev, struct vhost_virtqueue *vq)
> +{
> + /* Don't notify guest if we don't reach index specified by guest. */
> + if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) {
> + uint16_t old = vq->signalled_used;
> + uint16_t new = vq->last_used_idx;
> +
> + LOG_DEBUG(VHOST_DATA, "%s: used_event_idx=%d, old=%d, new=%d\n",
> + __func__,
> + vhost_used_event(vq),
> + old, new);
> + if (vring_need_event(vhost_used_event(vq), new, old)
It's a bit weird that you use one from the standard linux header file
(vring_need_event), while you define you own one (vhost_used_event).
Note that the system header file also has "vring_used_event()" defined.
Besides that, I have few more comments (and some requirements):
- It'd be much better if there is a Tested-by tag. Expeclitly,
I'm asking a test with Linux kernel virtio-net driver in guest.
- I also hope you could have done a build test on some old distributions.
AFAIK, the two macros (vring_need_event and vring_used_event) come
from kernel 3.0 (or above). Any kernel older than that would fail
the build.
- I'd be great if you could make a new one based on top of my latest
tree: I have just applied a patchset that should conflict with this
one.
--yliu
Hi
> -----Original Message-----
> From: Yuanhan Liu [mailto:yliu@fridaylinux.org]
> Sent: Monday, January 8, 2018 10:07 PM
> To: Chen, Junjie J <junjie.j.chen@intel.com>
> Cc: Wang, Xiao W <xiao.w.wang@intel.com>; maxime.coquelin@redhat.com;
> Bie, Tiwei <tiwei.bie@intel.com>; dev@dpdk.org; Yao, Lei A
> <lei.a.yao@intel.com>
> Subject: Re: [PATCH v6] vhost: support virtqueue interrupt/notification
> suppression
>
> On Tue, Dec 26, 2017 at 12:43:10PM -0500, Junjie Chen wrote:
> > The driver can suppress interrupt when VIRTIO_F_EVENT_IDX feature bit
> > is negotiated. The driver set vring flags to 0, and MAY use used_event
> > in available ring to advise device interrupt util reach an index
> > specified by used_event. The device ignore the lower bit of vring
> > flags, and send an interrupt when index reach used_event.
> >
> > The device can suppress notification in a manner analogous to the ways
> > driver suppress interrupt. The device manipulates flags or avail_event
> > in the used ring in the same way the driver manipulates flags or
> > used_event in available ring.
> >
> > This patch is to enable this feature in vhost.
> >
> > Signed-off-by: Junjie Chen <junjie.j.chen@intel.com>
>
> You need put "---" before the change log. Otherwise, it will be tracked in the
> commit log.
Will update this.
>
> > +#define vhost_used_event(vr) \
> > + (*(volatile uint16_t*)&(vr)->avail->ring[(vr)->size])
> > +
> > +static __rte_always_inline void
> > +vhost_notify(struct virtio_net *dev, struct vhost_virtqueue *vq) {
> > + /* Don't notify guest if we don't reach index specified by guest. */
> > + if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) {
> > + uint16_t old = vq->signalled_used;
> > + uint16_t new = vq->last_used_idx;
> > +
> > + LOG_DEBUG(VHOST_DATA, "%s: used_event_idx=%d, old=%d,
> new=%d\n",
> > + __func__,
> > + vhost_used_event(vq),
> > + old, new);
> > + if (vring_need_event(vhost_used_event(vq), new, old)
>
> It's a bit weird that you use one from the standard linux header file
> (vring_need_event), while you define you own one (vhost_used_event).
> Note that the system header file also has "vring_used_event()" defined.
The vring_used_event is defined and used for virtio in kernel, kernel defines a vhost_used_event in vhost.c for vhost, so I just use a separated macro for vhost end.
I'd like to define both vhost_need_event and vhost_used_event in vhost.h to remove potential build issue in old linux distribution and also to keep consistent. Is that OK for you?
>
> Besides that, I have few more comments (and some requirements):
>
> - It'd be much better if there is a Tested-by tag. Expeclitly,
> I'm asking a test with Linux kernel virtio-net driver in guest.
Sure.
>
> - I also hope you could have done a build test on some old distributions.
> AFAIK, the two macros (vring_need_event and vring_used_event) come
> from kernel 3.0 (or above). Any kernel older than that would fail
> the build.
>
> - I'd be great if you could make a new one based on top of my latest
> tree: I have just applied a patchset that should conflict with this
> one.
Sure, will do this.
>
> --yliu
On Tue, Jan 09, 2018 at 02:12:02AM +0000, Chen, Junjie J wrote:
> > > + if (vring_need_event(vhost_used_event(vq), new, old)
> >
> > It's a bit weird that you use one from the standard linux header file
> > (vring_need_event), while you define you own one (vhost_used_event).
> > Note that the system header file also has "vring_used_event()" defined.
> The vring_used_event is defined and used for virtio in kernel, kernel defines a vhost_used_event in vhost.c for vhost, so I just use a separated macro for vhost end.
>
> I'd like to define both vhost_need_event and vhost_used_event in vhost.h to remove potential build issue in old linux distribution and also to keep consistent. Is that OK for you?
Yes.
--yliu
@@ -103,6 +103,8 @@ struct vhost_virtqueue {
uint16_t last_avail_idx;
uint16_t last_used_idx;
+ /* Last used index we notify to front end. */
+ uint16_t signalled_used;
#define VIRTIO_INVALID_EVENTFD (-1)
#define VIRTIO_UNINITIALIZED_EVENTFD (-2)
@@ -211,6 +213,7 @@ struct vhost_msg {
(1ULL << VIRTIO_NET_F_GUEST_TSO4) | \
(1ULL << VIRTIO_NET_F_GUEST_TSO6) | \
(1ULL << VIRTIO_RING_F_INDIRECT_DESC) | \
+ (1ULL << VIRTIO_RING_F_EVENT_IDX) | \
(1ULL << VIRTIO_NET_F_MTU) | \
(1ULL << VIRTIO_F_IOMMU_PLATFORM))
@@ -52,6 +52,34 @@
#define MAX_BATCH_LEN 256
+#define vhost_used_event(vr) \
+ (*(volatile uint16_t*)&(vr)->avail->ring[(vr)->size])
+
+static __rte_always_inline void
+vhost_notify(struct virtio_net *dev, struct vhost_virtqueue *vq)
+{
+ /* Don't notify guest if we don't reach index specified by guest. */
+ if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX)) {
+ uint16_t old = vq->signalled_used;
+ uint16_t new = vq->last_used_idx;
+
+ LOG_DEBUG(VHOST_DATA, "%s: used_event_idx=%d, old=%d, new=%d\n",
+ __func__,
+ vhost_used_event(vq),
+ old, new);
+ if (vring_need_event(vhost_used_event(vq), new, old)
+ && (vq->callfd >= 0)) {
+ vq->signalled_used = vq->last_used_idx;
+ eventfd_write(vq->callfd, (eventfd_t) 1);
+ }
+ } else {
+ /* Kick the guest if necessary. */
+ if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
+ && (vq->callfd >= 0))
+ eventfd_write(vq->callfd, (eventfd_t)1);
+ }
+}
+
static bool
is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t nr_vring)
{
@@ -410,11 +438,7 @@ virtio_dev_rx(struct virtio_net *dev, uint16_t queue_id,
/* flush used->idx update before we read avail->flags. */
rte_mb();
-
- /* Kick the guest if necessary. */
- if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
- && (vq->callfd >= 0))
- eventfd_write(vq->callfd, (eventfd_t)1);
+ vhost_notify(dev, vq);
out:
if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
vhost_user_iotlb_rd_unlock(vq);
@@ -704,11 +728,7 @@ virtio_dev_merge_rx(struct virtio_net *dev, uint16_t queue_id,
/* flush used->idx update before we read avail->flags. */
rte_mb();
-
- /* Kick the guest if necessary. */
- if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
- && (vq->callfd >= 0))
- eventfd_write(vq->callfd, (eventfd_t)1);
+ vhost_notify(dev, vq);
}
out:
@@ -1106,11 +1126,7 @@ update_used_idx(struct virtio_net *dev, struct vhost_virtqueue *vq,
vq->used->idx += count;
vhost_log_used_vring(dev, vq, offsetof(struct vring_used, idx),
sizeof(vq->used->idx));
-
- /* Kick guest if required. */
- if (!(vq->avail->flags & VRING_AVAIL_F_NO_INTERRUPT)
- && (vq->callfd >= 0))
- eventfd_write(vq->callfd, (eventfd_t)1);
+ vhost_notify(dev, vq);
}
static __rte_always_inline struct zcopy_mbuf *