On Fri, Mar 1, 2024 at 2:44 PM Jonah Palmer <jonah.pal...@oracle.com> wrote:
>
> Add support to virtio-pci devices for handling the extra data sent
> from the driver to the device when the VIRTIO_F_NOTIFICATION_DATA
> transport feature has been negotiated.
>
> The extra data that's passed to the virtio-pci device when this
> feature is enabled varies depending on the device's virtqueue
> layout.
>
> In a split virtqueue layout, this data includes:
> - upper 16 bits: last_avail_idx
> - lower 16 bits: virtqueue index
>
> In a packed virtqueue layout, this data includes:
> - upper 16 bits: 1-bit wrap counter & 15-bit last_avail_idx
> - lower 16 bits: virtqueue index
>
> Signed-off-by: Jonah Palmer <jonah.pal...@oracle.com>
> ---
> hw/virtio/virtio-pci.c | 13 ++++++++++---
> hw/virtio/virtio.c | 13 +++++++++++++
> include/hw/virtio/virtio.h | 1 +
> 3 files changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 1a7039fb0c..c7c577b177 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -384,7 +384,7 @@ static void virtio_ioport_write(void *opaque, uint32_t
> addr, uint32_t val)
> {
> VirtIOPCIProxy *proxy = opaque;
> VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> - uint16_t vector;
> + uint16_t vector, vq_idx;
> hwaddr pa;
>
> switch (addr) {
> @@ -408,8 +408,15 @@ static void virtio_ioport_write(void *opaque, uint32_t
> addr, uint32_t val)
> vdev->queue_sel = val;
> break;
> case VIRTIO_PCI_QUEUE_NOTIFY:
> - if (val < VIRTIO_QUEUE_MAX) {
> - virtio_queue_notify(vdev, val);
> + if (virtio_vdev_has_feature(vdev, VIRTIO_F_NOTIFICATION_DATA)) {
> + vq_idx = val & 0xFFFF;
Nitpick, but since vq_idx is already a uint16_t the & 0xFFFF is not
needed. I think it's cleaner just to call virtio_set_notification data
in the has_feature(...) condition, but I'm happy with this too.
> + virtio_set_notification_data(vdev, vq_idx, val);
> + } else {
> + vq_idx = val;
> + }
> +
> + if (vq_idx < VIRTIO_QUEUE_MAX) {
> + virtio_queue_notify(vdev, vq_idx);
> }
> break;
> case VIRTIO_PCI_STATUS:
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index d229755eae..a61f69b7fd 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2052,6 +2052,19 @@ int virtio_set_status(VirtIODevice *vdev, uint8_t val)
> return 0;
> }
>
> +void virtio_set_notification_data(VirtIODevice *vdev, uint16_t i, uint32_t
> data)
> +{
> + VirtQueue *vq = &vdev->vq[i];
> +
> + if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) {
> + vq->last_avail_wrap_counter = (data >> 31) & 0x1;
> + vq->last_avail_idx = (data >> 16) & 0x7FFF;
> + } else {
> + vq->last_avail_idx = (data >> 16) & 0xFFFF;
> + }
It should not set last_avail_idx, only shadow_avail_idx. Otherwise,
QEMU can only see the descriptors placed after the notification.
Or am I missing something?
In that regard, I would call this function
"virtqueue_set_shadow_avail_idx". But I'm very bad at naming :).
The rest looks good to me.
Thanks!
> + vq->shadow_avail_idx = vq->last_avail_idx;
> +}
> +
> static enum virtio_device_endian virtio_default_endian(void)
> {
> if (target_words_bigendian()) {
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index c8f72850bc..c92d8afc42 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -345,6 +345,7 @@ void virtio_queue_reset(VirtIODevice *vdev, uint32_t
> queue_index);
> void virtio_queue_enable(VirtIODevice *vdev, uint32_t queue_index);
> void virtio_update_irq(VirtIODevice *vdev);
> int virtio_set_features(VirtIODevice *vdev, uint64_t val);
> +void virtio_set_notification_data(VirtIODevice *vdev, uint16_t i, uint32_t
> data);
>
> /* Base devices. */
> typedef struct VirtIOBlkConf VirtIOBlkConf;
> --
> 2.39.3
>
