On Mon, 16 Oct 2023 16:19:08 +0100
David Woodhouse <dwmw2@xxxxxxxxxxxxx> wrote:
> From: David Woodhouse <dwmw@xxxxxxxxxxxx>
>
is this index a user (guest) visible?
> There's no need to force the user to assign a vdev. We can automatically
> assign one, starting at xvda and searching until we find the first disk
> name that's unused.
>
> This means we can now allow '-drive if=xen,file=xxx' to work without an
> explicit separate -driver argument, just like if=virtio.
>
> Signed-off-by: David Woodhouse <dwmw@xxxxxxxxxxxx>
> ---
> blockdev.c | 15 ++++++++++++---
> hw/block/xen-block.c | 25 +++++++++++++++++++++++++
> 2 files changed, 37 insertions(+), 3 deletions(-)
>
> diff --git a/blockdev.c b/blockdev.c
> index 325b7a3bef..9dec4c9c74 100644
> --- a/blockdev.c
> +++ b/blockdev.c
> @@ -255,13 +255,13 @@ void drive_check_orphaned(void)
> * Ignore default drives, because we create certain default
> * drives unconditionally, then leave them unclaimed. Not the
> * users fault.
> - * Ignore IF_VIRTIO, because it gets desugared into -device,
> - * so we can leave failing to -device.
> + * Ignore IF_VIRTIO or IF_XEN, because it gets desugared into
> + * -device, so we can leave failing to -device.
> * Ignore IF_NONE, because leaving unclaimed IF_NONE remains
> * available for device_add is a feature.
> */
> if (dinfo->is_default || dinfo->type == IF_VIRTIO
> - || dinfo->type == IF_NONE) {
> + || dinfo->type == IF_XEN || dinfo->type == IF_NONE) {
> continue;
> }
> if (!blk_get_attached_dev(blk)) {
> @@ -977,6 +977,15 @@ DriveInfo *drive_new(QemuOpts *all_opts, BlockInterfaceType block_default_type,
> qemu_opt_set(devopts, "driver", "virtio-blk", &error_abort);
> qemu_opt_set(devopts, "drive", qdict_get_str(bs_opts, "id"),
> &error_abort);
> + } else if (type == IF_XEN) {
> + QemuOpts *devopts;
> + devopts = qemu_opts_create(qemu_find_opts("device"), NULL, 0,
> + &error_abort);
> + qemu_opt_set(devopts, "driver",
> + (media == MEDIA_CDROM) ? "xen-cdrom" : "xen-disk",
> + &error_abort);
> + qemu_opt_set(devopts, "drive", qdict_get_str(bs_opts, "id"),
> + &error_abort);
> }
>
> filename = qemu_opt_get(legacy_opts, "file");
> diff --git a/hw/block/xen-block.c b/hw/block/xen-block.c
> index 9262338535..20fa783cbe 100644
> --- a/hw/block/xen-block.c
> +++ b/hw/block/xen-block.c
> @@ -34,6 +34,31 @@ static char *xen_block_get_name(XenDevice *xendev, Error **errp)
> XenBlockDevice *blockdev = XEN_BLOCK_DEVICE(xendev);
> XenBlockVdev *vdev = &blockdev->props.vdev;
>
> + if (blockdev->props.vdev.type == XEN_BLOCK_VDEV_TYPE_INVALID) {
> + char name[11];
> + int disk = 0;
> + unsigned long idx;
> +
> + /* Find an unoccupied device name */
> + while (disk < (1 << 20)) {
> + if (disk < (1 << 4)) {
> + idx = (202 << 8) | (disk << 4);
> + } else {
> + idx = (1 << 28) | (disk << 8);
> + }
> + snprintf(name, sizeof(name), "%lu", idx);
> + if (!xen_backend_exists("qdisk", name)) {
> + vdev->type = XEN_BLOCK_VDEV_TYPE_XVD;
> + vdev->partition = 0;
> + vdev->disk = disk;
> + vdev->number = idx;
> + return g_strdup(name);
> + }
> + disk++;
> + }
> + error_setg(errp, "cannot find device vdev for block device");
> + return NULL;
> + }
> return g_strdup_printf("%lu", vdev->number);
> }
>
