linux-kernel - Re: [PATCH 4/4] vdpa_sim: Implement stop vdpa op

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Date:   Mon, 23 May 2022 21:07:54 +0200
From:   Eugenio Perez Martin <eperezma@...hat.com>
To:     Stefano Garzarella <sgarzare@...hat.com>
Cc:     virtualization <virtualization@...ts.linux-foundation.org>,
        Jason Wang <jasowang@...hat.com>,
        kvm list <kvm@...r.kernel.org>,
        "Michael S. Tsirkin" <mst@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Longpeng <longpeng2@...wei.com>,
        Zhu Lingshan <lingshan.zhu@...el.com>,
        Martin Petrus Hubertus Habets <martinh@...inx.com>,
        Harpreet Singh Anand <hanand@...inx.com>,
        Si-Wei Liu <si-wei.liu@...cle.com>, dinang@...inx.com,
        Eli Cohen <elic@...dia.com>,
        Laurent Vivier <lvivier@...hat.com>, pabloc@...inx.com,
        "Dawar, Gautam" <gautam.dawar@....com>,
        Xie Yongji <xieyongji@...edance.com>, habetsm.xilinx@...il.com,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        tanuj.kamde@....com, Wu Zongyong <wuzongyong@...ux.alibaba.com>,
        martinpo@...inx.com, Cindy Lu <lulu@...hat.com>,
        ecree.xilinx@...il.com, Parav Pandit <parav@...dia.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Zhang Min <zhang.min9@....com.cn>
Subject: Re: [PATCH 4/4] vdpa_sim: Implement stop vdpa op

On Mon, May 23, 2022 at 10:28 AM Stefano Garzarella <sgarzare@...hat.com> wrote:
>
> On Fri, May 20, 2022 at 07:23:25PM +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).
> >
> >Signed-off-by: Eugenio Pérez <eperezma@...hat.com>
> >---
> > drivers/vdpa/vdpa_sim/vdpa_sim.c     | 21 +++++++++++++++++++++
> > drivers/vdpa/vdpa_sim/vdpa_sim.h     |  1 +
> > drivers/vdpa/vdpa_sim/vdpa_sim_net.c |  3 +++
> > 3 files changed, 25 insertions(+)
> >
> >diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> >index 50d721072beb..0515cf314bed 100644
> >--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
> >+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
> >@@ -107,6 +107,7 @@ static void vdpasim_do_reset(struct vdpasim *vdpasim)
> >       for (i = 0; i < vdpasim->dev_attr.nas; i++)
> >               vhost_iotlb_reset(&vdpasim->iommu[i]);
> >
> >+      vdpasim->running = true;
> >       spin_unlock(&vdpasim->iommu_lock);
> >
> >       vdpasim->features = 0;
> >@@ -505,6 +506,24 @@ static int vdpasim_reset(struct vdpa_device *vdpa)
> >       return 0;
> > }
> >
> >+static int vdpasim_stop(struct vdpa_device *vdpa, bool stop)
> >+{
> >+      struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> >+      int i;
> >+
> >+      spin_lock(&vdpasim->lock);
> >+      vdpasim->running = !stop;
> >+      if (vdpasim->running) {
> >+              /* Check for missed buffers */
> >+              for (i = 0; i < vdpasim->dev_attr.nvqs; ++i)
> >+                      vdpasim_kick_vq(vdpa, i);
> >+
> >+      }
> >+      spin_unlock(&vdpasim->lock);
> >+
> >+      return 0;
> >+}
> >+
> > static size_t vdpasim_get_config_size(struct vdpa_device *vdpa)
> > {
> >       struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
> >@@ -694,6 +713,7 @@ static const struct vdpa_config_ops vdpasim_config_ops = {
> >       .get_status             = vdpasim_get_status,
> >       .set_status             = vdpasim_set_status,
> >       .reset                  = vdpasim_reset,
> >+      .stop                   = vdpasim_stop,
> >       .get_config_size        = vdpasim_get_config_size,
> >       .get_config             = vdpasim_get_config,
> >       .set_config             = vdpasim_set_config,
> >@@ -726,6 +746,7 @@ static const struct vdpa_config_ops vdpasim_batch_config_ops = {
> >       .get_status             = vdpasim_get_status,
> >       .set_status             = vdpasim_set_status,
> >       .reset                  = vdpasim_reset,
> >+      .stop                   = vdpasim_stop,
> >       .get_config_size        = vdpasim_get_config_size,
> >       .get_config             = vdpasim_get_config,
> >       .set_config             = vdpasim_set_config,
> >diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vdpa_sim.h
> >index 622782e92239..061986f30911 100644
> >--- a/drivers/vdpa/vdpa_sim/vdpa_sim.h
> >+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.h
> >@@ -66,6 +66,7 @@ struct vdpasim {
> >       u32 generation;
> >       u64 features;
> >       u32 groups;
> >+      bool running;
> >       /* spinlock to synchronize iommu table */
> >       spinlock_t iommu_lock;
> > };
> >diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
> >index 5125976a4df8..886449e88502 100644
> >--- a/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
> >+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_net.c
> >@@ -154,6 +154,9 @@ static void vdpasim_net_work(struct work_struct *work)
> >
> >       spin_lock(&vdpasim->lock);
> >
> >+      if (!vdpasim->running)
> >+              goto out;
> >+
>
> It would be nice to do the same for vdpa_sim_blk as well.
>

Agree, it will be added in the next revision. If not, blk presents an
invalid backend feature bit.

Thanks!

> Thanks,
> Stefano
>