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authorNicholas Bellinger <nab@linux-iscsi.org>2013-03-27 17:23:41 -0700
committerNicholas Bellinger <nab@linux-iscsi.org>2013-03-28 23:42:47 -0700
commit5dade71050e799d8679698a6145e2ba46cdeac2a (patch)
tree305a6afdd30ea073b0ce6fc8ee952405993bff16 /drivers/vhost
parent8f27d487bcc2bd603c2d87e1729abcbc301f15db (diff)
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>
Diffstat (limited to 'drivers/vhost')
-rw-r--r--drivers/vhost/tcm_vhost.c13
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
index 43fb11ee2e8d..2968b4934659 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
@@ -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;