From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH] tcm_vhost: Avoid VIRTIO_RING_F_EVENT_IDX feature bit Date: Thu, 28 Mar 2013 08:04:46 +0200 Message-ID: <20130328060446.GA16579@redhat.com> References: <1364430430-968-1-git-send-email-nab@linux-iscsi.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: target-devel , lf-virt , kvm-devel , Stefan Hajnoczi , Paolo Bonzini , Asias He , Anthony Liguori To: "Nicholas A. Bellinger" Return-path: Content-Disposition: inline In-Reply-To: <1364430430-968-1-git-send-email-nab@linux-iscsi.org> Sender: target-devel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Thu, Mar 28, 2013 at 12:27:10AM +0000, Nicholas A. Bellinger wrote: > From: Nicholas Bellinger > > This patch adds a VHOST_TCM_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. > > Cc: Michael S. Tsirkin > Cc: Asias He > Cc: Paolo Bonzini > Signed-off-by: Nicholas Bellinger No chance we can debug this properly? > --- > drivers/vhost/tcm_vhost.c | 10 ++++++++-- > 1 files changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c > index 0524267..b127edc 100644 > --- a/drivers/vhost/tcm_vhost.c > +++ b/drivers/vhost/tcm_vhost.c > @@ -60,6 +60,12 @@ enum { > VHOST_SCSI_VQ_IO = 2, > }; > > +enum { > + VHOST_TCM_FEATURES = (1ULL << VIRTIO_F_NOTIFY_ON_EMPTY) | > + (1ULL << VIRTIO_RING_F_INDIRECT_DESC) | > + (1ULL << VHOST_F_LOG_ALL) All the rest of the code uses VHOST_SCSI so rename this too? > +}; > + Please do something like +/* +* 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 +987,7 @@ 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_TCM_FEATURES) > return -EOPNOTSUPP; > > mutex_lock(&vs->dev.mutex); > @@ -1027,7 +1033,7 @@ static long vhost_scsi_ioctl(struct file *f, unsigned int ioctl, > return -EFAULT; > return 0; > case VHOST_GET_FEATURES: > - features = VHOST_FEATURES; > + features = VHOST_TCM_FEATURES; > if (copy_to_user(featurep, &features, sizeof features)) > return -EFAULT; > return 0; > -- > 1.7.2.5