On Wed, Mar 11, 2026 at 3:10 AM Eugenio Pérez <[email protected]> wrote: > > Implement suspend operation for vduse devices, so vhost-vdpa will offer > that backend feature and userspace can effectively suspend the device. > > This is a must before get virtqueue indexes (base) for live migration, > since the device could modify them after userland gets them.
As discussed in the pervious version, let's explain why and the plan to support resume. > > Signed-off-by: Eugenio Pérez <[email protected]> > --- > This patch depends on > https://lore.kernel.org/lkml/[email protected] > > v2: > * Take the rwsem only before the actual kick, not in vduse_vdpa_kick_vq. > This assures that we're not in a critical section. > --- > drivers/vdpa/vdpa_user/vduse_dev.c | 86 +++++++++++++++++++++++++++++- > include/uapi/linux/vduse.h | 4 ++ > 2 files changed, 88 insertions(+), 2 deletions(-) > > diff --git a/drivers/vdpa/vdpa_user/vduse_dev.c > b/drivers/vdpa/vdpa_user/vduse_dev.c > index 4f642b95a7cb..f56b1e3eb82d 100644 > --- a/drivers/vdpa/vdpa_user/vduse_dev.c > +++ b/drivers/vdpa/vdpa_user/vduse_dev.c > @@ -54,7 +54,8 @@ > #define IRQ_UNBOUND -1 > > /* Supported VDUSE features */ > -static const uint64_t vduse_features = BIT_U64(VDUSE_F_QUEUE_READY); > +static const uint64_t vduse_features = BIT_U64(VDUSE_F_QUEUE_READY) | > + BIT_U64(VDUSE_F_SUSPEND); > > /* > * VDUSE instance have not asked the vduse API version, so assume 0. > @@ -85,6 +86,7 @@ struct vduse_virtqueue { > int irq_effective_cpu; > struct cpumask irq_affinity; > struct kobject kobj; > + struct vduse_dev *dev; > }; > > struct vduse_dev; > @@ -134,6 +136,7 @@ struct vduse_dev { > int minor; > bool broken; > bool connected; > + bool suspended; > u64 api_version; > u64 device_features; > u64 driver_features; > @@ -480,6 +483,7 @@ static void vduse_dev_reset(struct vduse_dev *dev) > > down_write(&dev->rwsem); > > + dev->suspended = false; > dev->status = 0; > dev->driver_features = 0; > dev->generation++; > @@ -538,6 +542,10 @@ static void vduse_vq_kick(struct vduse_virtqueue *vq) > if (!vq->ready) > goto unlock; > > + guard(rwsem_read)(&vq->dev->rwsem); > + if (vq->dev->suspended) > + return; Any reason for this? E.g We don't do this for other transports. Everything else looks good. Thanks
