? 2022/1/22 ??4:27, Eugenio P?rez ??:> This function allows the vhost-vdpa backend to override kick_fd.
>
> Signed-off-by: Eugenio P?rez <eperezma at redhat.com>
> ---
> hw/virtio/vhost-shadow-virtqueue.h | 1 +
> hw/virtio/vhost-shadow-virtqueue.c | 45 ++++++++++++++++++++++++++++++
> 2 files changed, 46 insertions(+)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.h
b/hw/virtio/vhost-shadow-virtqueue.h
> index 400effd9f2..a56ecfc09d 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.h
> +++ b/hw/virtio/vhost-shadow-virtqueue.h
> @@ -15,6 +15,7 @@
>
> typedef struct VhostShadowVirtqueue VhostShadowVirtqueue;
>
> +void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int
svq_kick_fd);
> const EventNotifier *vhost_svq_get_dev_kick_notifier(
> const VhostShadowVirtqueue
*svq);
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c
b/hw/virtio/vhost-shadow-virtqueue.c
> index bd87110073..21534bc94d 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -11,6 +11,7 @@
> #include "hw/virtio/vhost-shadow-virtqueue.h"
>
> #include "qemu/error-report.h"
> +#include "qemu/main-loop.h"
>
> /* Shadow virtqueue to relay notifications */
> typedef struct VhostShadowVirtqueue {
> @@ -18,8 +19,20 @@ typedef struct VhostShadowVirtqueue {
> EventNotifier hdev_kick;
> /* Shadow call notifier, sent to vhost */
> EventNotifier hdev_call;
> +
> + /*
> + * Borrowed virtqueue's guest to host notifier.
> + * To borrow it in this event notifier allows to register on the event
> + * loop and access the associated shadow virtqueue easily. If we use
the
> + * VirtQueue, we don't have an easy way to retrieve it.
> + *
> + * So shadow virtqueue must not clean it, or we would lose VirtQueue
one.
> + */
> + EventNotifier svq_kick;
> } VhostShadowVirtqueue;
>
> +#define INVALID_SVQ_KICK_FD -1
> +
> /**
> * The notifier that SVQ will use to notify the device.
> */
> @@ -29,6 +42,35 @@ const EventNotifier *vhost_svq_get_dev_kick_notifier(
> return &svq->hdev_kick;
> }
>
> +/**
> + * Set a new file descriptor for the guest to kick SVQ and notify for
avail
> + *
> + * @svq The svq
> + * @svq_kick_fd The new svq kick fd
> + */
> +void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd)
> +{
> + EventNotifier tmp;
> + bool check_old = INVALID_SVQ_KICK_FD !> +
event_notifier_get_fd(&svq->svq_kick);
> +
> + if (check_old) {
> + event_notifier_set_handler(&svq->svq_kick, NULL);
> + event_notifier_init_fd(&tmp,
event_notifier_get_fd(&svq->svq_kick));
> + }
It looks to me we don't do similar things in vhost-net. Any reason for
caring about the old svq_kick?
> +
> + /*
> + * event_notifier_set_handler already checks for guest's
notifications if
> + * they arrive to the new file descriptor in the switch, so there is
no
> + * need to explicitely check for them.
> + */
> + event_notifier_init_fd(&svq->svq_kick, svq_kick_fd);
> +
> + if (!check_old || event_notifier_test_and_clear(&tmp)) {
> + event_notifier_set(&svq->hdev_kick);
Any reason we need to kick the device directly here?
Thanks
> + }
> +}
> +
> /**
> * Creates vhost shadow virtqueue, and instruct vhost device to use the
shadow
> * methods and file descriptors.
> @@ -52,6 +94,9 @@ VhostShadowVirtqueue *vhost_svq_new(void)
> goto err_init_hdev_call;
> }
>
> + /* Placeholder descriptor, it should be deleted at set_kick_fd */
> + event_notifier_init_fd(&svq->svq_kick, INVALID_SVQ_KICK_FD);
> +
> return g_steal_pointer(&svq);
>
> err_init_hdev_call: