* Re: Re: [RFC v7] virtio/vsock: add two more queues for datagram types
@ 2021-09-22 17:36 Jiang Wang .
2021-09-23 9:18 ` Stefano Garzarella
0 siblings, 1 reply; 4+ messages in thread
From: Jiang Wang . @ 2021-09-22 17:36 UTC (permalink / raw)
To: Stefano Garzarella
Cc: Arseny Krasnov, Jason Wang, qemu devel list, Stefan Hajnoczi,
Michael S. Tsirkin
On Wed, Sep 22, 2021 at 2:23 AM Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> On Wed, Sep 22, 2021 at 12:00:24AM +0000, Jiang Wang wrote:
> >Datagram sockets are connectionless and unreliable.
> >The sender does not know the capacity of the receiver
> >and may send more packets than the receiver can handle.
> >
> >Add two more dedicate virtqueues for datagram sockets,
> >so that it will not unfairly steal resources from
> >stream and future connection-oriented sockets.
> >
> >The two new virtqueues are enabled by default and will
> >be removed if the guest does not support. This will help
> >migration work.
> >
> >btw: enable_dgram argument in vhost_vsock_common_realize
> >is redundant for now, but will be used later when we
> >want to disable DGRAM feature bit for old versions.
> >
> >Signed-off-by: Jiang Wang <jiang.wang@bytedance.com>
> >---
> >v1 -> v2: use qemu cmd option to control number of queues,
> > removed configuration settings for dgram.
> >v2 -> v3: use ioctl to get features and decide number of
> > virt queues, instead of qemu cmd option.
> >v3 -> v4: change DGRAM feature bit value to 2. Add an argument
> > in vhost_vsock_common_realize to indicate dgram is supported or not.
> >v4 -> v5: don't open dev to get vhostfd. Removed leftover definition of
> > enable_dgram
> >v5 -> v6: fix style errors. Imporve error handling of
> > vhost_vsock_dgram_supported. Rename MAX_VQS_WITH_DGRAM and another one.
> >v6 -> v7: Always enable dgram for vhost-user and vhost kernel.
> > Delete unused virtqueues at the beginning of
> > vhost_vsock_common_start for migration. Otherwise, migration will fail.
> >
> > hw/virtio/vhost-user-vsock.c | 2 +-
> > hw/virtio/vhost-vsock-common.c | 32 +++++++++++++++++--
> > hw/virtio/vhost-vsock.c | 6 +++-
> > include/hw/virtio/vhost-vsock-common.h | 6 ++--
> > include/hw/virtio/vhost-vsock.h | 3 ++
> > include/standard-headers/linux/virtio_vsock.h | 1 +
> > 6 files changed, 43 insertions(+), 7 deletions(-)
> >
> >diff --git a/hw/virtio/vhost-user-vsock.c b/hw/virtio/vhost-user-vsock.c
> >index 6095ed7349..9823a2f3bd 100644
> >--- a/hw/virtio/vhost-user-vsock.c
> >+++ b/hw/virtio/vhost-user-vsock.c
> >@@ -105,7 +105,7 @@ static void vuv_device_realize(DeviceState *dev, Error **errp)
> > return;
> > }
> >
> >- vhost_vsock_common_realize(vdev, "vhost-user-vsock");
> >+ vhost_vsock_common_realize(vdev, "vhost-user-vsock", true);
> >
> > vhost_dev_set_config_notifier(&vvc->vhost_dev, &vsock_ops);
> >
> >diff --git a/hw/virtio/vhost-vsock-common.c b/hw/virtio/vhost-vsock-common.c
> >index 4ad6e234ad..7d89b4d242 100644
> >--- a/hw/virtio/vhost-vsock-common.c
> >+++ b/hw/virtio/vhost-vsock-common.c
> >@@ -26,6 +26,18 @@ int vhost_vsock_common_start(VirtIODevice *vdev)
> > int ret;
> > int i;
> >
> >+ if (!virtio_has_feature(vdev->guest_features, VIRTIO_VSOCK_F_DGRAM)) {
> >+ struct vhost_virtqueue *vqs;
> >+ virtio_delete_queue(vvc->dgram_recv_vq);
> >+ virtio_delete_queue(vvc->dgram_trans_vq);
> >+
>
> Are you sure it works removing queues here?
> The event_queue would always be #4, but the guest will use #2 which
> we're removing.
>
Yes, this works. In fact, I should include this in v6 and my tests done
in my previous emails have these changes. But before I submitted the patch,
I thought this code was redundant and removed it without further testing.
To explain it, I think the event queue number does not matter for the
vhost and qemu. The vhost-vsock kernel module does not allocate any
data structure for the event queue. Qemu also only allocates an array of
size 2 or 4 for the tx, rx queues. The event queue is handled separately.
The event queue number only shows up in the spec, but in real code, I don't
see anywhere that the event queue number is used explicitly or implicitly.
The Event queue looks independent of tx, rx queues.
> >+ vqs = vvc->vhost_dev.vqs;
> >+ vvc->vhost_dev.nvqs = MAX_VQS_WITHOUT_DGRAM;
> >+ vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue,
> >+ vvc->vhost_dev.nvqs);
> >+ g_free(vqs);
> >+ }
> >+
> > if (!k->set_guest_notifiers) {
> > error_report("binding does not support guest notifiers");
> > return -ENOSYS;
> >@@ -196,9 +208,11 @@ int vhost_vsock_common_post_load(void *opaque, int version_id)
> > return 0;
> > }
> >
> >-void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name)
> >+void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name,
> >+ bool enable_dgram)
> ^
> It seems always true, and also unused.
>
Yes, I can remove it. I am just wondering when we modify the feature
bit as in your recent seqpacket patch, do we want to change it to false when
the feature is not supported and make the code logically more resonable？
Or do we still make it true even if the feature bit is not supported?
> > {
> > VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
> >+ int nvqs = MAX_VQS_WITH_DGRAM;
> >
> > virtio_init(vdev, name, VIRTIO_ID_VSOCK,
> > sizeof(struct virtio_vsock_config));
> >@@ -209,12 +223,17 @@ void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name)
> > vvc->trans_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> > vhost_vsock_common_handle_output);
> >
> >+ vvc->dgram_recv_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> >+ vhost_vsock_common_handle_output);
> >+ vvc->dgram_trans_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> >+ vhost_vsock_common_handle_output);
> >+
> > /* The event queue belongs to QEMU */
> > vvc->event_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> > vhost_vsock_common_handle_output);
> >
> >- vvc->vhost_dev.nvqs = ARRAY_SIZE(vvc->vhost_vqs);
> >- vvc->vhost_dev.vqs = vvc->vhost_vqs;
> >+ vvc->vhost_dev.nvqs = nvqs;
> >+ vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue, vvc->vhost_dev.nvqs);
> >
> > vvc->post_load_timer = NULL;
> > }
> >@@ -227,6 +246,13 @@ void vhost_vsock_common_unrealize(VirtIODevice *vdev)
> >
> > virtio_delete_queue(vvc->recv_vq);
> > virtio_delete_queue(vvc->trans_vq);
> >+ if (vvc->vhost_dev.nvqs == MAX_VQS_WITH_DGRAM) {
> >+ virtio_delete_queue(vvc->dgram_recv_vq);
> >+ virtio_delete_queue(vvc->dgram_trans_vq);
> >+ }
> >+
> >+ g_free(vvc->vhost_dev.vqs);
> >+
> > virtio_delete_queue(vvc->event_vq);
> > virtio_cleanup(vdev);
> > }
> >diff --git a/hw/virtio/vhost-vsock.c b/hw/virtio/vhost-vsock.c
> >index 1b1a5c70ed..6e315ecf23 100644
> >--- a/hw/virtio/vhost-vsock.c
> >+++ b/hw/virtio/vhost-vsock.c
> >@@ -23,6 +23,7 @@
> >
> > const int feature_bits[] = {
> > VIRTIO_VSOCK_F_SEQPACKET,
> >+ VIRTIO_VSOCK_F_DGRAM,
> > VHOST_INVALID_FEATURE_BIT
> > };
> >
> >@@ -116,6 +117,9 @@ static uint64_t vhost_vsock_get_features(VirtIODevice *vdev,
> > VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
> >
> > virtio_add_feature(&requested_features, VIRTIO_VSOCK_F_SEQPACKET);
> >+ if (vvc->vhost_dev.nvqs == MAX_VQS_WITH_DGRAM) {
> >+ virtio_add_feature(&requested_features, VIRTIO_VSOCK_F_DGRAM);
> >+ }
>
> Take a look at
> https://lore.kernel.org/qemu-devel/20210921161642.206461-1-sgarzare@redhat.com/
>
Yes, I noticed that email. Thanks for reminding me. I did not make
similar changes yet because I want to wait for that patch to be merged.
I can start to make similar changes in the next version.
> If it will be accepted, we should use something similar (e.g.
> `datagram` prop) and handle this flag in vhost-vsock-common.
>
> And we should change a bit the queue handling:
> - if QEMU (new `datagram` prop is `on` or `auto`) and the kernel
> supports F_DGRAM, we can allocate 5 queues.
Agree with the new prop. But when the kernel supports F_DGRAM, qemu
still only allocates 4 queues. As in the following code：
vvc->vhost_dev.nvqs = nvqs;
vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue, vvc->vhost_dev.nvqs);
// nvqs will be either 2 or 4. Will not be 5. btw, in the new version, it will
// always be 4.
> - if the guest acked F_DGRAM we can use queue #4 for events, otherwise
> switch back to queue #2, without removing them.
>
> > return vhost_get_features(&vvc->vhost_dev, feature_bits,
> > requested_features);
> > }
> >@@ -175,7 +179,7 @@ static void vhost_vsock_device_realize(DeviceState *dev, Error **errp)
> > qemu_set_nonblock(vhostfd);
> > }
> >
> >- vhost_vsock_common_realize(vdev, "vhost-vsock");
> >+ vhost_vsock_common_realize(vdev, "vhost-vsock", true);
> >
> > ret = vhost_dev_init(&vvc->vhost_dev, (void *)(uintptr_t)vhostfd,
> > VHOST_BACKEND_TYPE_KERNEL, 0, errp);
> >diff --git a/include/hw/virtio/vhost-vsock-common.h b/include/hw/virtio/vhost-vsock-common.h
> >index e412b5ee98..80151aee35 100644
> >--- a/include/hw/virtio/vhost-vsock-common.h
> >+++ b/include/hw/virtio/vhost-vsock-common.h
> >@@ -27,12 +27,13 @@ enum {
> > struct VHostVSockCommon {
> > VirtIODevice parent;
> >
> >- struct vhost_virtqueue vhost_vqs[2];
> > struct vhost_dev vhost_dev;
> >
> > VirtQueue *event_vq;
> > VirtQueue *recv_vq;
> > VirtQueue *trans_vq;
> >+ VirtQueue *dgram_recv_vq;
> >+ VirtQueue *dgram_trans_vq;
> >
> > QEMUTimer *post_load_timer;
> > };
> >@@ -41,7 +42,8 @@ int vhost_vsock_common_start(VirtIODevice *vdev);
> > void vhost_vsock_common_stop(VirtIODevice *vdev);
> > int vhost_vsock_common_pre_save(void *opaque);
> > int vhost_vsock_common_post_load(void *opaque, int version_id);
> >-void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name);
> >+void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name,
> >+ bool enable_dgram);
> > void vhost_vsock_common_unrealize(VirtIODevice *vdev);
> >
> > #endif /* _QEMU_VHOST_VSOCK_COMMON_H */
> >diff --git a/include/hw/virtio/vhost-vsock.h b/include/hw/virtio/vhost-vsock.h
> >index 84f4e727c7..7d16c0e218 100644
> >--- a/include/hw/virtio/vhost-vsock.h
> >+++ b/include/hw/virtio/vhost-vsock.h
> >@@ -33,4 +33,7 @@ struct VHostVSock {
> > /*< public >*/
> > };
> >
> >+#define MAX_VQS_WITHOUT_DGRAM 2
> >+#define MAX_VQS_WITH_DGRAM 4
>
> I think was better the naming in the previous version.
>
Sure, will change it back in the next version.
> Thanks,
> Stefano
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [RFC v7] virtio/vsock: add two more queues for datagram types
2021-09-22 17:36 Re: [RFC v7] virtio/vsock: add two more queues for datagram types Jiang Wang .
@ 2021-09-23 9:18 ` Stefano Garzarella
2021-09-24 22:27 ` [External] " Jiang Wang .
0 siblings, 1 reply; 4+ messages in thread
From: Stefano Garzarella @ 2021-09-23 9:18 UTC (permalink / raw)
To: Jiang Wang .
Cc: Arseny Krasnov, Jason Wang, qemu devel list, Stefan Hajnoczi,
Michael S. Tsirkin
On Wed, Sep 22, 2021 at 10:36:24AM -0700, Jiang Wang . wrote:
>On Wed, Sep 22, 2021 at 2:23 AM Stefano Garzarella <sgarzare@redhat.com> wrote:
>>
>> On Wed, Sep 22, 2021 at 12:00:24AM +0000, Jiang Wang wrote:
>> >Datagram sockets are connectionless and unreliable.
>> >The sender does not know the capacity of the receiver
>> >and may send more packets than the receiver can handle.
>> >
>> >Add two more dedicate virtqueues for datagram sockets,
>> >so that it will not unfairly steal resources from
>> >stream and future connection-oriented sockets.
>> >
>> >The two new virtqueues are enabled by default and will
>> >be removed if the guest does not support. This will help
>> >migration work.
>> >
>> >btw: enable_dgram argument in vhost_vsock_common_realize
>> >is redundant for now, but will be used later when we
>> >want to disable DGRAM feature bit for old versions.
>> >
>> >Signed-off-by: Jiang Wang <jiang.wang@bytedance.com>
>> >---
>> >v1 -> v2: use qemu cmd option to control number of queues,
>> > removed configuration settings for dgram.
>> >v2 -> v3: use ioctl to get features and decide number of
>> > virt queues, instead of qemu cmd option.
>> >v3 -> v4: change DGRAM feature bit value to 2. Add an argument
>> > in vhost_vsock_common_realize to indicate dgram is supported or not.
>> >v4 -> v5: don't open dev to get vhostfd. Removed leftover definition of
>> > enable_dgram
>> >v5 -> v6: fix style errors. Imporve error handling of
>> > vhost_vsock_dgram_supported. Rename MAX_VQS_WITH_DGRAM and another one.
>> >v6 -> v7: Always enable dgram for vhost-user and vhost kernel.
>> > Delete unused virtqueues at the beginning of
>> > vhost_vsock_common_start for migration. Otherwise, migration will fail.
>> >
>> > hw/virtio/vhost-user-vsock.c | 2 +-
>> > hw/virtio/vhost-vsock-common.c | 32 +++++++++++++++++--
>> > hw/virtio/vhost-vsock.c | 6 +++-
>> > include/hw/virtio/vhost-vsock-common.h | 6 ++--
>> > include/hw/virtio/vhost-vsock.h | 3 ++
>> > include/standard-headers/linux/virtio_vsock.h | 1 +
>> > 6 files changed, 43 insertions(+), 7 deletions(-)
>> >
>> >diff --git a/hw/virtio/vhost-user-vsock.c b/hw/virtio/vhost-user-vsock.c
>> >index 6095ed7349..9823a2f3bd 100644
>> >--- a/hw/virtio/vhost-user-vsock.c
>> >+++ b/hw/virtio/vhost-user-vsock.c
>> >@@ -105,7 +105,7 @@ static void vuv_device_realize(DeviceState *dev, Error **errp)
>> > return;
>> > }
>> >
>> >- vhost_vsock_common_realize(vdev, "vhost-user-vsock");
>> >+ vhost_vsock_common_realize(vdev, "vhost-user-vsock", true);
>> >
>> > vhost_dev_set_config_notifier(&vvc->vhost_dev, &vsock_ops);
>> >
>> >diff --git a/hw/virtio/vhost-vsock-common.c b/hw/virtio/vhost-vsock-common.c
>> >index 4ad6e234ad..7d89b4d242 100644
>> >--- a/hw/virtio/vhost-vsock-common.c
>> >+++ b/hw/virtio/vhost-vsock-common.c
>> >@@ -26,6 +26,18 @@ int vhost_vsock_common_start(VirtIODevice *vdev)
>> > int ret;
>> > int i;
>> >
>> >+ if (!virtio_has_feature(vdev->guest_features, VIRTIO_VSOCK_F_DGRAM)) {
>> >+ struct vhost_virtqueue *vqs;
>> >+ virtio_delete_queue(vvc->dgram_recv_vq);
>> >+ virtio_delete_queue(vvc->dgram_trans_vq);
>> >+
>>
>> Are you sure it works removing queues here?
>> The event_queue would always be #4, but the guest will use #2 which
>> we're removing.
>>
>Yes, this works. In fact, I should include this in v6 and my tests done
>in my previous emails have these changes. But before I submitted the patch,
>I thought this code was redundant and removed it without further testing.
Just tried on an host that doesn't support F_DGRAM and I have the
following errors:
qemu-system-x86_64: -device vhost-vsock-pci,guest-cid=6: vhost_set_vring_call failed: No buffer space available (105)
qemu-system-x86_64: -device vhost-vsock-pci,guest-cid=6: Failed to initialize virtqueue 2: No buffer space available
I thinks we should re-add the feature discovery before call
vhost_dev_init().
>
>To explain it, I think the event queue number does not matter for the
>vhost and qemu. The vhost-vsock kernel module does not allocate any
>data structure for the event queue. Qemu also only allocates an array of
>size 2 or 4 for the tx, rx queues. The event queue is handled separately.
>
>The event queue number only shows up in the spec, but in real code, I don't
>see anywhere that the event queue number is used explicitly or implicitly.
>The Event queue looks independent of tx, rx queues.
Yep, it is used in the linux driver. Look at
virtio_transport_event_work(), it uses VSOCK_VQ_EVENT (2).
The main test to do is to migrate a guest with active connections that
doesn't support F_DGRAM on an host that support it and check if, after
the migration, the connections are reset and the CID updated.
I think is not working now.
>
>> >+ vqs = vvc->vhost_dev.vqs;
>> >+ vvc->vhost_dev.nvqs = MAX_VQS_WITHOUT_DGRAM;
>> >+ vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue,
>> >+ vvc->vhost_dev.nvqs);
>> >+ g_free(vqs);
>> >+ }
>> >+
>> > if (!k->set_guest_notifiers) {
>> > error_report("binding does not support guest notifiers");
>> > return -ENOSYS;
>> >@@ -196,9 +208,11 @@ int vhost_vsock_common_post_load(void *opaque, int version_id)
>> > return 0;
>> > }
>> >
>> >-void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name)
>> >+void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name,
>> >+ bool enable_dgram)
>> ^
>> It seems always true, and also unused.
>>
>Yes, I can remove it. I am just wondering when we modify the feature
>bit as in your recent seqpacket patch, do we want to change it to false when
>the feature is not supported and make the code logically more
>resonable？
>Or do we still make it true even if the feature bit is not supported?
Maybe we need to use it because now vhost_dev_init is failing if the
host doesn't support F_DGRAM since we are registering more queues than
the device can handle.
>
>> > {
>> > VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
>> >+ int nvqs = MAX_VQS_WITH_DGRAM;
>> >
>> > virtio_init(vdev, name, VIRTIO_ID_VSOCK,
>> > sizeof(struct virtio_vsock_config));
>> >@@ -209,12 +223,17 @@ void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name)
>> > vvc->trans_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
>> > vhost_vsock_common_handle_output);
>> >
>> >+ vvc->dgram_recv_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
>> >+ vhost_vsock_common_handle_output);
>> >+ vvc->dgram_trans_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
>> >+ vhost_vsock_common_handle_output);
>> >+
>> > /* The event queue belongs to QEMU */
>> > vvc->event_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
>> > vhost_vsock_common_handle_output);
>> >
>> >- vvc->vhost_dev.nvqs = ARRAY_SIZE(vvc->vhost_vqs);
>> >- vvc->vhost_dev.vqs = vvc->vhost_vqs;
>> >+ vvc->vhost_dev.nvqs = nvqs;
>> >+ vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue, vvc->vhost_dev.nvqs);
>> >
>> > vvc->post_load_timer = NULL;
>> > }
>> >@@ -227,6 +246,13 @@ void vhost_vsock_common_unrealize(VirtIODevice *vdev)
>> >
>> > virtio_delete_queue(vvc->recv_vq);
>> > virtio_delete_queue(vvc->trans_vq);
>> >+ if (vvc->vhost_dev.nvqs == MAX_VQS_WITH_DGRAM) {
>> >+ virtio_delete_queue(vvc->dgram_recv_vq);
>> >+ virtio_delete_queue(vvc->dgram_trans_vq);
>> >+ }
>> >+
>> >+ g_free(vvc->vhost_dev.vqs);
>> >+
>> > virtio_delete_queue(vvc->event_vq);
>> > virtio_cleanup(vdev);
>> > }
>> >diff --git a/hw/virtio/vhost-vsock.c b/hw/virtio/vhost-vsock.c
>> >index 1b1a5c70ed..6e315ecf23 100644
>> >--- a/hw/virtio/vhost-vsock.c
>> >+++ b/hw/virtio/vhost-vsock.c
>> >@@ -23,6 +23,7 @@
>> >
>> > const int feature_bits[] = {
>> > VIRTIO_VSOCK_F_SEQPACKET,
>> >+ VIRTIO_VSOCK_F_DGRAM,
>> > VHOST_INVALID_FEATURE_BIT
>> > };
>> >
>> >@@ -116,6 +117,9 @@ static uint64_t vhost_vsock_get_features(VirtIODevice *vdev,
>> > VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
>> >
>> > virtio_add_feature(&requested_features, VIRTIO_VSOCK_F_SEQPACKET);
>> >+ if (vvc->vhost_dev.nvqs == MAX_VQS_WITH_DGRAM) {
>> >+ virtio_add_feature(&requested_features, VIRTIO_VSOCK_F_DGRAM);
>> >+ }
>>
>> Take a look at
>> https://lore.kernel.org/qemu-devel/20210921161642.206461-1-sgarzare@redhat.com/
>>
>Yes, I noticed that email. Thanks for reminding me. I did not make
>similar changes yet because I want to wait for that patch to be merged.
>I can start to make similar changes in the next version.
Yep, better to wait comments on that series.
>
>> If it will be accepted, we should use something similar (e.g.
>> `datagram` prop) and handle this flag in vhost-vsock-common.
>>
>> And we should change a bit the queue handling:
>> - if QEMU (new `datagram` prop is `on` or `auto`) and the kernel
>> supports F_DGRAM, we can allocate 5 queues.
>Agree with the new prop. But when the kernel supports F_DGRAM, qemu
>still only allocates 4 queues. As in the following code：
>
>vvc->vhost_dev.nvqs = nvqs;
>vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue,
>vvc->vhost_dev.nvqs);
>
>// nvqs will be either 2 or 4. Will not be 5. btw, in the new version, it will
>// always be 4.
Sorry, with allocating I meant virtio_add_queue() calls.
Just to be clear, I think we should do something like this:
#define VHOST_VSOCK_NVQS 3
#define VHOST_VSOCK_NVQS_DGRAM 5
#define VHOST_VSOCK_MAX_VQS VHOST_VSOCK_NVQS_DGRAM
struct VHostVSockCommon {
...
VirtQueue *vqs[VHOST_VSOCK_MAX_VQS];
int event_vq_id;
}
void vhost_vsock_common_realize(...)
{
int nvqs = VHOST_VSOCK_NVQS;
...
if (enable_dgram) {
nvqs = VHOST_VSOCK_NVQS_DGRAM;
}
...
for (i = 0; i < nvqs; i++) {
vvc->vqs[i] = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
vhost_vsock_common_handle_output);
}
/* event queue is not handled by the vhost device */
vvc->vhost_dev.nvqs = nvqs - 1;
vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue, vvc->vhost_dev.nvqs);
...
}
int vhost_vsock_common_start(...)
{
...
if (virtio_has_feature(vdev->guest_features, VIRTIO_VSOCK_F_DGRAM)) {
vvc->event_vq_id = VHOST_VSOCK_NVQS_DGRAM - 1;
} else {
vvc->event_vq_id = VHOST_VSOCK_NVQS - 1;
}
...
}
Then use `vvc->event_vq_id` in :
- vhost_vsock_common_send_transport_reset()
- vhost_vsock_common_post_load() (instead of 2 wired in the code)
Maybe in vhost_vsock_common_send_transport_reset() we can skip the
message enqueueing if the device is not started
(vvc->vhost_dev.started).
Thanks,
Stefano
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [External] Re: [RFC v7] virtio/vsock: add two more queues for datagram types
2021-09-23 9:18 ` Stefano Garzarella
@ 2021-09-24 22:27 ` Jiang Wang .
2021-09-27 14:36 ` Stefano Garzarella
0 siblings, 1 reply; 4+ messages in thread
From: Jiang Wang . @ 2021-09-24 22:27 UTC (permalink / raw)
To: Stefano Garzarella
Cc: Arseny Krasnov, Jason Wang, qemu devel list, Stefan Hajnoczi,
Michael S. Tsirkin
On Thu, Sep 23, 2021 at 2:18 AM Stefano Garzarella <sgarzare@redhat.com> wrote:
>
> On Wed, Sep 22, 2021 at 10:36:24AM -0700, Jiang Wang . wrote:
> >On Wed, Sep 22, 2021 at 2:23 AM Stefano Garzarella <sgarzare@redhat.com> wrote:
> >>
> >> On Wed, Sep 22, 2021 at 12:00:24AM +0000, Jiang Wang wrote:
> >> >Datagram sockets are connectionless and unreliable.
> >> >The sender does not know the capacity of the receiver
> >> >and may send more packets than the receiver can handle.
> >> >
> >> >Add two more dedicate virtqueues for datagram sockets,
> >> >so that it will not unfairly steal resources from
> >> >stream and future connection-oriented sockets.
> >> >
> >> >The two new virtqueues are enabled by default and will
> >> >be removed if the guest does not support. This will help
> >> >migration work.
> >> >
> >> >btw: enable_dgram argument in vhost_vsock_common_realize
> >> >is redundant for now, but will be used later when we
> >> >want to disable DGRAM feature bit for old versions.
> >> >
> >> >Signed-off-by: Jiang Wang <jiang.wang@bytedance.com>
> >> >---
> >> >v1 -> v2: use qemu cmd option to control number of queues,
> >> > removed configuration settings for dgram.
> >> >v2 -> v3: use ioctl to get features and decide number of
> >> > virt queues, instead of qemu cmd option.
> >> >v3 -> v4: change DGRAM feature bit value to 2. Add an argument
> >> > in vhost_vsock_common_realize to indicate dgram is supported or not.
> >> >v4 -> v5: don't open dev to get vhostfd. Removed leftover definition of
> >> > enable_dgram
> >> >v5 -> v6: fix style errors. Imporve error handling of
> >> > vhost_vsock_dgram_supported. Rename MAX_VQS_WITH_DGRAM and another one.
> >> >v6 -> v7: Always enable dgram for vhost-user and vhost kernel.
> >> > Delete unused virtqueues at the beginning of
> >> > vhost_vsock_common_start for migration. Otherwise, migration will fail.
> >> >
> >> > hw/virtio/vhost-user-vsock.c | 2 +-
> >> > hw/virtio/vhost-vsock-common.c | 32 +++++++++++++++++--
> >> > hw/virtio/vhost-vsock.c | 6 +++-
> >> > include/hw/virtio/vhost-vsock-common.h | 6 ++--
> >> > include/hw/virtio/vhost-vsock.h | 3 ++
> >> > include/standard-headers/linux/virtio_vsock.h | 1 +
> >> > 6 files changed, 43 insertions(+), 7 deletions(-)
> >> >
> >> >diff --git a/hw/virtio/vhost-user-vsock.c b/hw/virtio/vhost-user-vsock.c
> >> >index 6095ed7349..9823a2f3bd 100644
> >> >--- a/hw/virtio/vhost-user-vsock.c
> >> >+++ b/hw/virtio/vhost-user-vsock.c
> >> >@@ -105,7 +105,7 @@ static void vuv_device_realize(DeviceState *dev, Error **errp)
> >> > return;
> >> > }
> >> >
> >> >- vhost_vsock_common_realize(vdev, "vhost-user-vsock");
> >> >+ vhost_vsock_common_realize(vdev, "vhost-user-vsock", true);
> >> >
> >> > vhost_dev_set_config_notifier(&vvc->vhost_dev, &vsock_ops);
> >> >
> >> >diff --git a/hw/virtio/vhost-vsock-common.c b/hw/virtio/vhost-vsock-common.c
> >> >index 4ad6e234ad..7d89b4d242 100644
> >> >--- a/hw/virtio/vhost-vsock-common.c
> >> >+++ b/hw/virtio/vhost-vsock-common.c
> >> >@@ -26,6 +26,18 @@ int vhost_vsock_common_start(VirtIODevice *vdev)
> >> > int ret;
> >> > int i;
> >> >
> >> >+ if (!virtio_has_feature(vdev->guest_features, VIRTIO_VSOCK_F_DGRAM)) {
> >> >+ struct vhost_virtqueue *vqs;
> >> >+ virtio_delete_queue(vvc->dgram_recv_vq);
> >> >+ virtio_delete_queue(vvc->dgram_trans_vq);
> >> >+
> >>
> >> Are you sure it works removing queues here?
> >> The event_queue would always be #4, but the guest will use #2 which
> >> we're removing.
> >>
> >Yes, this works. In fact, I should include this in v6 and my tests done
> >in my previous emails have these changes. But before I submitted the patch,
> >I thought this code was redundant and removed it without further testing.
>
> Just tried on an host that doesn't support F_DGRAM and I have the
> following errors:
> qemu-system-x86_64: -device vhost-vsock-pci,guest-cid=6: vhost_set_vring_call failed: No buffer space available (105)
> qemu-system-x86_64: -device vhost-vsock-pci,guest-cid=6: Failed to initialize virtqueue 2: No buffer space available
>
> I thinks we should re-add the feature discovery before call
> vhost_dev_init().
>
Yes. You are right. I will add it back.
> >
> >To explain it, I think the event queue number does not matter for the
> >vhost and qemu. The vhost-vsock kernel module does not allocate any
> >data structure for the event queue. Qemu also only allocates an array of
> >size 2 or 4 for the tx, rx queues. The event queue is handled separately.
> >
> >The event queue number only shows up in the spec, but in real code, I don't
> >see anywhere that the event queue number is used explicitly or implicitly.
> >The Event queue looks independent of tx, rx queues.
>
> Yep, it is used in the linux driver. Look at
> virtio_transport_event_work(), it uses VSOCK_VQ_EVENT (2).
>
Agree, it is used in virtio driver and QEMU as you mentioned later.
> The main test to do is to migrate a guest with active connections that
By active connections, do you mean active vsock stream connections?
The guest should be the server or the client? I have two simple vsock client,
server tests which only send messages for each direction once. Or I can also
use something like iperf3.
> doesn't support F_DGRAM on an host that support it and check if, after
> the migration, the connections are reset and the CID updated.
Not sure about why CID should be updated? Right now, on the destination
host, I used the same CID as the one on the source host. You mean choose
another guest CID on the destination host? I will try that.
> I think is not working now.
>
> >
> >> >+ vqs = vvc->vhost_dev.vqs;
> >> >+ vvc->vhost_dev.nvqs = MAX_VQS_WITHOUT_DGRAM;
> >> >+ vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue,
> >> >+ vvc->vhost_dev.nvqs);
> >> >+ g_free(vqs);
> >> >+ }
> >> >+
> >> > if (!k->set_guest_notifiers) {
> >> > error_report("binding does not support guest notifiers");
> >> > return -ENOSYS;
> >> >@@ -196,9 +208,11 @@ int vhost_vsock_common_post_load(void *opaque, int version_id)
> >> > return 0;
> >> > }
> >> >
> >> >-void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name)
> >> >+void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name,
> >> >+ bool enable_dgram)
> >> ^
> >> It seems always true, and also unused.
> >>
> >Yes, I can remove it. I am just wondering when we modify the feature
> >bit as in your recent seqpacket patch, do we want to change it to false when
> >the feature is not supported and make the code logically more
> >resonable？
> >Or do we still make it true even if the feature bit is not supported?
>
> Maybe we need to use it because now vhost_dev_init is failing if the
> host doesn't support F_DGRAM since we are registering more queues than
> the device can handle.
>
Sure.
> >
> >> > {
> >> > VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
> >> >+ int nvqs = MAX_VQS_WITH_DGRAM;
> >> >
> >> > virtio_init(vdev, name, VIRTIO_ID_VSOCK,
> >> > sizeof(struct virtio_vsock_config));
> >> >@@ -209,12 +223,17 @@ void vhost_vsock_common_realize(VirtIODevice *vdev, const char *name)
> >> > vvc->trans_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> >> > vhost_vsock_common_handle_output);
> >> >
> >> >+ vvc->dgram_recv_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> >> >+ vhost_vsock_common_handle_output);
> >> >+ vvc->dgram_trans_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> >> >+ vhost_vsock_common_handle_output);
> >> >+
> >> > /* The event queue belongs to QEMU */
> >> > vvc->event_vq = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> >> > vhost_vsock_common_handle_output);
> >> >
> >> >- vvc->vhost_dev.nvqs = ARRAY_SIZE(vvc->vhost_vqs);
> >> >- vvc->vhost_dev.vqs = vvc->vhost_vqs;
> >> >+ vvc->vhost_dev.nvqs = nvqs;
> >> >+ vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue, vvc->vhost_dev.nvqs);
> >> >
> >> > vvc->post_load_timer = NULL;
> >> > }
> >> >@@ -227,6 +246,13 @@ void vhost_vsock_common_unrealize(VirtIODevice *vdev)
> >> >
> >> > virtio_delete_queue(vvc->recv_vq);
> >> > virtio_delete_queue(vvc->trans_vq);
> >> >+ if (vvc->vhost_dev.nvqs == MAX_VQS_WITH_DGRAM) {
> >> >+ virtio_delete_queue(vvc->dgram_recv_vq);
> >> >+ virtio_delete_queue(vvc->dgram_trans_vq);
> >> >+ }
> >> >+
> >> >+ g_free(vvc->vhost_dev.vqs);
> >> >+
> >> > virtio_delete_queue(vvc->event_vq);
> >> > virtio_cleanup(vdev);
> >> > }
> >> >diff --git a/hw/virtio/vhost-vsock.c b/hw/virtio/vhost-vsock.c
> >> >index 1b1a5c70ed..6e315ecf23 100644
> >> >--- a/hw/virtio/vhost-vsock.c
> >> >+++ b/hw/virtio/vhost-vsock.c
> >> >@@ -23,6 +23,7 @@
> >> >
> >> > const int feature_bits[] = {
> >> > VIRTIO_VSOCK_F_SEQPACKET,
> >> >+ VIRTIO_VSOCK_F_DGRAM,
> >> > VHOST_INVALID_FEATURE_BIT
> >> > };
> >> >
> >> >@@ -116,6 +117,9 @@ static uint64_t vhost_vsock_get_features(VirtIODevice *vdev,
> >> > VHostVSockCommon *vvc = VHOST_VSOCK_COMMON(vdev);
> >> >
> >> > virtio_add_feature(&requested_features, VIRTIO_VSOCK_F_SEQPACKET);
> >> >+ if (vvc->vhost_dev.nvqs == MAX_VQS_WITH_DGRAM) {
> >> >+ virtio_add_feature(&requested_features, VIRTIO_VSOCK_F_DGRAM);
> >> >+ }
> >>
> >> Take a look at
> >> https://lore.kernel.org/qemu-devel/20210921161642.206461-1-sgarzare@redhat.com/
> >>
> >Yes, I noticed that email. Thanks for reminding me. I did not make
> >similar changes yet because I want to wait for that patch to be merged.
> >I can start to make similar changes in the next version.
>
> Yep, better to wait comments on that series.
>
OK.
> >
> >> If it will be accepted, we should use something similar (e.g.
> >> `datagram` prop) and handle this flag in vhost-vsock-common.
> >>
> >> And we should change a bit the queue handling:
> >> - if QEMU (new `datagram` prop is `on` or `auto`) and the kernel
> >> supports F_DGRAM, we can allocate 5 queues.
> >Agree with the new prop. But when the kernel supports F_DGRAM, qemu
> >still only allocates 4 queues. As in the following code：
> >
> >vvc->vhost_dev.nvqs = nvqs;
> >vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue,
> >vvc->vhost_dev.nvqs);
> >
> >// nvqs will be either 2 or 4. Will not be 5. btw, in the new version, it will
> >// always be 4.
>
> Sorry, with allocating I meant virtio_add_queue() calls.
>
> Just to be clear, I think we should do something like this:
>
> #define VHOST_VSOCK_NVQS 3
> #define VHOST_VSOCK_NVQS_DGRAM 5
> #define VHOST_VSOCK_MAX_VQS VHOST_VSOCK_NVQS_DGRAM
>
> struct VHostVSockCommon {
> ...
>
> VirtQueue *vqs[VHOST_VSOCK_MAX_VQS];
>
> int event_vq_id;
> }
>
> void vhost_vsock_common_realize(...)
> {
> int nvqs = VHOST_VSOCK_NVQS;
>
> ...
>
> if (enable_dgram) {
> nvqs = VHOST_VSOCK_NVQS_DGRAM;
> }
>
> ...
>
> for (i = 0; i < nvqs; i++) {
> vvc->vqs[i] = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> vhost_vsock_common_handle_output);
> }
>
> /* event queue is not handled by the vhost device */
> vvc->vhost_dev.nvqs = nvqs - 1;
> vvc->vhost_dev.vqs = g_new0(struct vhost_virtqueue, vvc->vhost_dev.nvqs);
>
> ...
> }
>
> int vhost_vsock_common_start(...)
> {
> ...
>
> if (virtio_has_feature(vdev->guest_features, VIRTIO_VSOCK_F_DGRAM)) {
> vvc->event_vq_id = VHOST_VSOCK_NVQS_DGRAM - 1;
> } else {
> vvc->event_vq_id = VHOST_VSOCK_NVQS - 1;
> }
>
> ...
> }
>
I see. The example code helps a lot.
> Then use `vvc->event_vq_id` in :
> - vhost_vsock_common_send_transport_reset()
> - vhost_vsock_common_post_load() (instead of 2 wired in the code)
I see now vhost_vsock_common_post_load() has a problem. One way
to fix it is as you mentioned. Another way is to check the acked feature
bit here too and change the event queue number to 2 or 4 accordingly.
In your example code:
vvc->vqs[i] = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
vhost_vsock_common_handle_output);
We still need to do some assignment as following:
vvc->recv_vq = vvc->vqs[0];
vvc->trans_vq = vvc->vqs[1];
...(skipped other similar assignments)
I think both ways will work. Your example adds ordering for those recv and
trans vqs and makes it similar to virtio and vhost code. I will go that route.
>
> Maybe in vhost_vsock_common_send_transport_reset() we can skip the
> message enqueueing if the device is not started
> (vvc->vhost_dev.started).
>
OK. Btw, I can make this a separate change because it looks like a
standalone bugfix? I.e, not related to dgram?
> Thanks,
> Stefano
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [External] Re: [RFC v7] virtio/vsock: add two more queues for datagram types
2021-09-24 22:27 ` [External] " Jiang Wang .
@ 2021-09-27 14:36 ` Stefano Garzarella
0 siblings, 0 replies; 4+ messages in thread
From: Stefano Garzarella @ 2021-09-27 14:36 UTC (permalink / raw)
To: Jiang Wang .
Cc: Arseny Krasnov, Jason Wang, qemu devel list, Stefan Hajnoczi,
Michael S. Tsirkin
On Fri, Sep 24, 2021 at 03:27:30PM -0700, Jiang Wang . wrote:
>On Thu, Sep 23, 2021 at 2:18 AM Stefano Garzarella <sgarzare@redhat.com> wrote:
[...]
>> >
>> >To explain it, I think the event queue number does not matter for the
>> >vhost and qemu. The vhost-vsock kernel module does not allocate any
>> >data structure for the event queue. Qemu also only allocates an array of
>> >size 2 or 4 for the tx, rx queues. The event queue is handled
>> >separately.
>> >
>> >The event queue number only shows up in the spec, but in real code, I don't
>> >see anywhere that the event queue number is used explicitly or implicitly.
>> >The Event queue looks independent of tx, rx queues.
>>
>> Yep, it is used in the linux driver. Look at
>> virtio_transport_event_work(), it uses VSOCK_VQ_EVENT (2).
>>
>Agree, it is used in virtio driver and QEMU as you mentioned later.
>
>> The main test to do is to migrate a guest with active connections that
>By active connections, do you mean active vsock stream connections?
Yep, e.g using ncat also without exchanging data. After the migration
the socket should be reset by the driver if the event queue is working.
>The guest should be the server or the client?
Doesn't matter.
> I have two simple vsock client,
>server tests which only send messages for each direction once. Or I can also
>use something like iperf3.
>
>> doesn't support F_DGRAM on an host that support it and check if, after
>> the migration, the connections are reset and the CID updated.
>
>Not sure about why CID should be updated? Right now, on the destination
>host, I used the same CID as the one on the source host. You mean choose
>another guest CID on the destination host? I will try that.
Yep, because another thing the driver does when it handles the event in
the event queue is to update the guest CID.
Usually you should use different CIDs if you migrate on the same host.
>
>> I think is not working now.
>>
[...]
>>
>I see. The example code helps a lot.
>
>> Then use `vvc->event_vq_id` in :
>> - vhost_vsock_common_send_transport_reset()
>> - vhost_vsock_common_post_load() (instead of 2 wired in the code)
>I see now vhost_vsock_common_post_load() has a problem. One way
>to fix it is as you mentioned. Another way is to check the acked feature
>bit here too and change the event queue number to 2 or 4 accordingly.
>
>In your example code:
>vvc->vqs[i] = virtio_add_queue(vdev, VHOST_VSOCK_QUEUE_SIZE,
> vhost_vsock_common_handle_output);
>We still need to do some assignment as following:
>vvc->recv_vq = vvc->vqs[0];
>vvc->trans_vq = vvc->vqs[1];
>...(skipped other similar assignments)
Why we need this?
QEMU handles only the event queue.
recv_vq, trans_vq pointers are never used (only to deallocate).
>
>I think both ways will work. Your example adds ordering for those recv and
>trans vqs and makes it similar to virtio and vhost code. I will go that route.
Make sense.
>
>>
>> Maybe in vhost_vsock_common_send_transport_reset() we can skip the
>> message enqueueing if the device is not started
>> (vvc->vhost_dev.started).
>>
>OK. Btw, I can make this a separate change because it looks like a
>standalone bugfix? I.e, not related to dgram?
Yep, sure.
Stefano
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-09-27 14:39 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-09-22 17:36 Re: [RFC v7] virtio/vsock: add two more queues for datagram types Jiang Wang .
2021-09-23 9:18 ` Stefano Garzarella
2021-09-24 22:27 ` [External] " Jiang Wang .
2021-09-27 14:36 ` Stefano Garzarella
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