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tcm_vhost: Avoid VIRTIO_RING_F_EVENT_IDX feature bit 

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)

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Asias He <asias@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
This commit is contained in:
Nicholas Bellinger 2013-03-27 17:23:41 -07:00
parent 8f27d487bc
commit 5dade71050
1 changed files with 11 additions and 2 deletions
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13
drivers/vhost/tcm_vhost.c
View File

@ -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
@ -946,7 +955,7 @@ 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);
@ -992,7 +1001,7 @@ 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;