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authorNicholas Bellinger <nab@linux-iscsi.org>2013-03-27 20:23:41 -0400
committerNicholas Bellinger <nab@linux-iscsi.org>2013-03-29 02:42:47 -0400
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 {
60 VHOST_SCSI_VQ_IO = 2, 60 VHOST_SCSI_VQ_IO = 2,
61}; 61};
62 62
63/*
64 * VIRTIO_RING_F_EVENT_IDX seems broken. Not sure the bug is in
65 * kernel but disabling it helps.
66 * TODO: debug and remove the workaround.
67 */
68enum {
69 VHOST_SCSI_FEATURES = VHOST_FEATURES & (~VIRTIO_RING_F_EVENT_IDX)
70};
71
63#define VHOST_SCSI_MAX_TARGET 256 72#define VHOST_SCSI_MAX_TARGET 256
64#define VHOST_SCSI_MAX_VQ 128 73#define VHOST_SCSI_MAX_VQ 128
65 74
@@ -946,7 +955,7 @@ static void vhost_scsi_flush(struct vhost_scsi *vs)
946 955
947static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features) 956static int vhost_scsi_set_features(struct vhost_scsi *vs, u64 features)
948{ 957{
949 if (features & ~VHOST_FEATURES) 958 if (features & ~VHOST_SCSI_FEATURES)
950 return -EOPNOTSUPP; 959 return -EOPNOTSUPP;
951 960
952 mutex_lock(&vs->dev.mutex); 961 mutex_lock(&vs->dev.mutex);
@@ -992,7 +1001,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl,
992 return -EFAULT; 1001 return -EFAULT;
993 return 0; 1002 return 0;
994 case VHOST_GET_FEATURES: 1003 case VHOST_GET_FEATURES:
995 features = VHOST_FEATURES; 1004 features = VHOST_SCSI_FEATURES;
996 if (copy_to_user(featurep, &features, sizeof features)) 1005 if (copy_to_user(featurep, &features, sizeof features))
997 return -EFAULT; 1006 return -EFAULT;
998 return 0; 1007 return 0;