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 <20220523082738.h7lvwkysnqhynf37@sgarzare-redhat>
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From:   Eugenio Perez Martin <eperezma@redhat.com>
Date:   Mon, 23 May 2022 21:07:54 +0200
Message-ID: <CAJaqyWd0L3ihByNxQfHsra=vd9SYCBWk8sqhFmm0Lcz4gz=5wA@mail.gmail.com>
Subject: Re: [PATCH 4/4] vdpa_sim: Implement stop vdpa op
To:     Stefano Garzarella <sgarzare@redhat.com>
Cc:     virtualization <virtualization@lists.linux-foundation.org>,
        Jason Wang <jasowang@redhat.com>,
        kvm list <kvm@vger.kernel.org>,
        "Michael S. Tsirkin" <mst@redhat.com>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, Longpeng <longpeng2@huawei.com>,
        Zhu Lingshan <lingshan.zhu@intel.com>,
        Martin Petrus Hubertus Habets <martinh@xilinx.com>,
        Harpreet Singh Anand <hanand@xilinx.com>,
        Si-Wei Liu <si-wei.liu@oracle.com>, dinang@xilinx.com,
        Eli Cohen <elic@nvidia.com>,
        Laurent Vivier <lvivier@redhat.com>, pabloc@xilinx.com,
        "Dawar, Gautam" <gautam.dawar@amd.com>,
        Xie Yongji <xieyongji@bytedance.com>, habetsm.xilinx@gmail.com,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        tanuj.kamde@amd.com, Wu Zongyong <wuzongyong@linux.alibaba.com>,
        martinpo@xilinx.com, Cindy Lu <lulu@redhat.com>,
        ecree.xilinx@gmail.com, Parav Pandit <parav@nvidia.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Zhang Min <zhang.min9@zte.com.cn>
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On Mon, May 23, 2022 at 10:28 AM Stefano Garzarella <sgarzare@redhat.com> w=
rote:
>
> On Fri, May 20, 2022 at 07:23:25PM +0200, Eugenio P=C3=A9rez 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 P=C3=A9rez <eperezma@redhat.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/vd=
pa_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 =3D 0; i < vdpasim->dev_attr.nas; i++)
> >               vhost_iotlb_reset(&vdpasim->iommu[i]);
> >
> >+      vdpasim->running =3D true;
> >       spin_unlock(&vdpasim->iommu_lock);
> >
> >       vdpasim->features =3D 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 =3D vdpa_to_sim(vdpa);
> >+      int i;
> >+
> >+      spin_lock(&vdpasim->lock);
> >+      vdpasim->running =3D !stop;
> >+      if (vdpasim->running) {
> >+              /* Check for missed buffers */
> >+              for (i =3D 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 =3D vdpa_to_sim(vdpa);
> >@@ -694,6 +713,7 @@ static const struct vdpa_config_ops vdpasim_config_o=
ps =3D {
> >       .get_status             =3D vdpasim_get_status,
> >       .set_status             =3D vdpasim_set_status,
> >       .reset                  =3D vdpasim_reset,
> >+      .stop                   =3D vdpasim_stop,
> >       .get_config_size        =3D vdpasim_get_config_size,
> >       .get_config             =3D vdpasim_get_config,
> >       .set_config             =3D vdpasim_set_config,
> >@@ -726,6 +746,7 @@ static const struct vdpa_config_ops vdpasim_batch_co=
nfig_ops =3D {
> >       .get_status             =3D vdpasim_get_status,
> >       .set_status             =3D vdpasim_set_status,
> >       .reset                  =3D vdpasim_reset,
> >+      .stop                   =3D vdpasim_stop,
> >       .get_config_size        =3D vdpasim_get_config_size,
> >       .get_config             =3D vdpasim_get_config,
> >       .set_config             =3D vdpasim_set_config,
> >diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vd=
pa_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_si=
m/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 *wor=
k)
> >
> >       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
>