Nicholas A. Bellinger
2013-Mar-29 00:50 UTC
[PATCH-v2] tcm_vhost: Avoid VIRTIO_RING_F_EVENT_IDX feature bit
From: Nicholas Bellinger <nab at linux-iscsi.org>
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 at redhat.com>
Cc: Asias He <asias at redhat.com>
Cc: Paolo Bonzini <pbonzini at redhat.com>
Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>
---
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 He
2013-Mar-29 06:29 UTC
[PATCH-v2] tcm_vhost: Avoid VIRTIO_RING_F_EVENT_IDX feature bit
On Fri, Mar 29, 2013 at 12:50:26AM +0000, Nicholas A. Bellinger wrote:> From: Nicholas Bellinger <nab at linux-iscsi.org> > > 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 at redhat.com> > Cc: Asias He <asias at redhat.com> > Cc: Paolo Bonzini <pbonzini at redhat.com> > Signed-off-by: Nicholas Bellinger <nab at linux-iscsi.org>Reviewed-by: Asias He <asias at redhat.com>> --- > 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