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Message-ID: <20220811042847-mutt-send-email-mst@kernel.org> Date: Thu, 11 Aug 2022 04:29:06 -0400 From: "Michael S. Tsirkin" <mst@...hat.com> To: Eugenio Pérez <eperezma@...hat.com> Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, Jason Wang <jasowang@...hat.com>, virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org, dinang@...inx.com, martinpo@...inx.com, Wu Zongyong <wuzongyong@...ux.alibaba.com>, Piotr.Uminski@...el.com, gautam.dawar@....com, ecree.xilinx@...il.com, martinh@...inx.com, Stefano Garzarella <sgarzare@...hat.com>, pabloc@...inx.com, habetsm.xilinx@...il.com, lvivier@...hat.com, Zhu Lingshan <lingshan.zhu@...el.com>, tanuj.kamde@....com, Longpeng <longpeng2@...wei.com>, lulu@...hat.com, hanand@...inx.com, Parav Pandit <parav@...dia.com>, Si-Wei Liu <si-wei.liu@...cle.com>, Eli Cohen <elic@...dia.com>, Xie Yongji <xieyongji@...edance.com>, Zhang Min <zhang.min9@....com.cn>, Dan Carpenter <dan.carpenter@...cle.com>, Christophe JAILLET <christophe.jaillet@...adoo.fr> Subject: Re: [PATCH v7 3/4] vhost-vdpa: uAPI to suspend the device On Wed, Aug 10, 2022 at 07:15:11PM +0200, Eugenio Pérez wrote: > The ioctl adds support for suspending the device from userspace. > > This is a must before getting 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 a successful return of the ioctl call the device must not process > more virtqueue descriptors. The device can answer to read or writes of > config fields as if it were not suspended. In particular, writing to > "queue_enable" with a value of 1 will not make the device start > processing buffers of the virtqueue. > > Signed-off-by: Eugenio Pérez <eperezma@...hat.com> > Message-Id: <20220623160738.632852-4-eperezma@...hat.com> > Signed-off-by: Michael S. Tsirkin <mst@...hat.com> You are not supposed to include upstream maintainer's signoff like this. > --- > v7: Delete argument to ioctl, unused > --- > drivers/vhost/vdpa.c | 19 +++++++++++++++++++ > include/uapi/linux/vhost.h | 9 +++++++++ > 2 files changed, 28 insertions(+) > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > index 3d636e192061..7fa671ac4bdf 100644 > --- a/drivers/vhost/vdpa.c > +++ b/drivers/vhost/vdpa.c > @@ -478,6 +478,22 @@ static long vhost_vdpa_get_vqs_count(struct vhost_vdpa *v, u32 __user *argp) > return 0; > } > > +/* After a successful return of ioctl the device must not process more > + * virtqueue descriptors. The device can answer to read or writes of config > + * fields as if it were not suspended. In particular, writing to "queue_enable" > + * with a value of 1 will not make the device start processing buffers. > + */ > +static long vhost_vdpa_suspend(struct vhost_vdpa *v) > +{ > + struct vdpa_device *vdpa = v->vdpa; > + const struct vdpa_config_ops *ops = vdpa->config; > + > + if (!ops->suspend) > + return -EOPNOTSUPP; > + > + return ops->suspend(vdpa); > +} > + > static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, > void __user *argp) > { > @@ -654,6 +670,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep, > case VHOST_VDPA_GET_VQS_COUNT: > r = vhost_vdpa_get_vqs_count(v, argp); > break; > + case VHOST_VDPA_SUSPEND: > + r = vhost_vdpa_suspend(v); > + break; > default: > r = vhost_dev_ioctl(&v->vdev, cmd, argp); > if (r == -ENOIOCTLCMD) > diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h > index cab645d4a645..f9f115a7c75b 100644 > --- a/include/uapi/linux/vhost.h > +++ b/include/uapi/linux/vhost.h > @@ -171,4 +171,13 @@ > #define VHOST_VDPA_SET_GROUP_ASID _IOW(VHOST_VIRTIO, 0x7C, \ > struct vhost_vring_state) > > +/* Suspend a device so it does not process virtqueue requests anymore > + * > + * After the return of ioctl the device must 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. > + */ > +#define VHOST_VDPA_SUSPEND _IO(VHOST_VIRTIO, 0x7D) > + > #endif > -- > 2.31.1
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