On Thu, May 26, 2022 at 02:43:34PM +0200, Eugenio Pérez wrote: > Implement stop operation for vdpa_sim devices, so vhost-vdpa will offer > that backend feature and userspace can effectively stop the device. > > This is a must before get virtqueue indexes (base) for live migration, > since the device could modify them after userland gets them. There are > individual ways to perform that action for some devices > (VHOST_NET_SET_BACKEND, VHOST_VSOCK_SET_RUNNING, ...) but there was no > way to perform it for any vhost device (and, in particular, vhost-vdpa). > > After the return of ioctl with stop != 0, the device MUST finish any > pending operations like in flight requests. It must also preserve all > the necessary state (the virtqueue vring base plus the possible device > specific states) that is required for restoring in the future. The > device must not change its configuration after that point. > > After the return of ioctl with stop == 0, the device can continue > processing buffers as long as typical conditions are met (vq is enabled, > DRIVER_OK status bit is enabled, etc). > > In the future, we will provide features similar to VHOST_USER_GET_INFLIGHT_FD > so the device can save pending operations. > > Comments are welcome. So given this is just for simulator and affects UAPI I think it's fine to make it wait for the next merge window, until there's a consensus. Right? > v4: > * Replace VHOST_STOP to VHOST_VDPA_STOP in vhost ioctl switch case too. > > v3: > * s/VHOST_STOP/VHOST_VDPA_STOP/ > * Add documentation and requirements of the ioctl above its definition. > > v2: > * Replace raw _F_STOP with BIT_ULL(_F_STOP). > * Fix obtaining of stop ioctl arg (it was not obtained but written). > * Add stop to vdpa_sim_blk. > > Eugenio Pérez (4): > vdpa: Add stop operation > vhost-vdpa: introduce STOP backend feature bit > vhost-vdpa: uAPI to stop the device > vdpa_sim: Implement stop vdpa op > > drivers/vdpa/vdpa_sim/vdpa_sim.c | 21 +++++++++++++++++ > drivers/vdpa/vdpa_sim/vdpa_sim.h | 1 + > drivers/vdpa/vdpa_sim/vdpa_sim_blk.c | 3 +++ > drivers/vdpa/vdpa_sim/vdpa_sim_net.c | 3 +++ > drivers/vhost/vdpa.c | 34 +++++++++++++++++++++++++++- > include/linux/vdpa.h | 6 +++++ > include/uapi/linux/vhost.h | 14 ++++++++++++ > include/uapi/linux/vhost_types.h | 2 ++ > 8 files changed, 83 insertions(+), 1 deletion(-) > > -- > 2.31.1 >
