On Fri, Mar 29, 2013 at 12:50:26AM +0000, Nicholas A. Bellinger wrote:
> From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
>
> This patch adds a VHOST_SCSI_FEATURES mask minus VIRTIO_RING_F_EVENT_IDX
> so that vhost-scsi-pci userspace will strip this feature bit once
> GET_FEATURES reports it as being unsupported on the host.
>
> This is to avoid a bug where ->handle_kicks() are missed when EVENT_IDX
> is enabled by default in userspace code.
>
> (mst: Rename to VHOST_SCSI_FEATURES add comment)
>
> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
> Cc: Asias He <asias@xxxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Reviewed-by: Asias He <asias@xxxxxxxxxx>
> ---
> drivers/vhost/tcm_vhost.c | 13 +++++++++++--
> 1 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> index 0524267..4a68c1f 100644
> --- a/drivers/vhost/tcm_vhost.c
> +++ b/drivers/vhost/tcm_vhost.c
> @@ -60,6 +60,15 @@ enum {
> VHOST_SCSI_VQ_IO = 2,
> };
>
> +/*
> + * VIRTIO_RING_F_EVENT_IDX seems broken. Not sure the bug is in
> + * kernel but disabling it helps.
> + * TODO: debug and remove the workaround.
> + */
> +enum {
> + VHOST_SCSI_FEATURES = VHOST_FEATURES & (~VIRTIO_RING_F_EVENT_IDX)
> +};
> +
> #define VHOST_SCSI_MAX_TARGET 256
> #define VHOST_SCSI_MAX_VQ 128
>
> @@ -981,7 +990,7 @@ static void vhost_scsi_flush(struct vhost_scsi *vs)
>
> static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
> {
> - if (features & ~VHOST_FEATURES)
> + if (features & ~VHOST_SCSI_FEATURES)
> return -EOPNOTSUPP;
>
> mutex_lock(&vs->dev.mutex);
> @@ -1027,7 +1036,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
> return -EFAULT;
> return 0;
> case VHOST_GET_FEATURES:
> - features = VHOST_FEATURES;
> + features = VHOST_SCSI_FEATURES;
> if (copy_to_user(featurep, &features, sizeof features))
> return -EFAULT;
> return 0;
> --
> 1.7.2.5
>
--
Asias
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