linux-kernel - Re: [PATCH v4 4/4] vdpa_sim: Implement stop vdpa op

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Date:   Thu, 26 May 2022 16:25:06 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Eugenio Pérez <eperezma@...hat.com>
Cc:     "Michael S. Tsirkin" <mst@...hat.com>, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org, Jason Wang <jasowang@...hat.com>,
        netdev@...r.kernel.org, martinh@...inx.com, martinpo@...inx.com,
        lvivier@...hat.com, pabloc@...inx.com,
        Parav Pandit <parav@...dia.com>, Eli Cohen <elic@...dia.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Xie Yongji <xieyongji@...edance.com>,
        Christophe JAILLET <christophe.jaillet@...adoo.fr>,
        Zhang Min <zhang.min9@....com.cn>,
        Wu Zongyong <wuzongyong@...ux.alibaba.com>, lulu@...hat.com,
        Zhu Lingshan <lingshan.zhu@...el.com>, Piotr.Uminski@...el.com,
        Si-Wei Liu <si-wei.liu@...cle.com>, ecree.xilinx@...il.com,
        gautam.dawar@....com, habetsm.xilinx@...il.com,
        tanuj.kamde@....com, hanand@...inx.com, dinang@...inx.com,
        Longpeng <longpeng2@...wei.com>
Subject: Re: [PATCH v4 4/4] vdpa_sim: Implement stop vdpa op

On Thu, May 26, 2022 at 02:43:38PM +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_blk.c |  3 +++
> drivers/vdpa/vdpa_sim/vdpa_sim_net.c |  3 +++
> 4 files changed, 28 insertions(+)

Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>

>
>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_blk.c b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
>index 42d401d43911..bcdb1982c378 100644
>--- a/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
>+++ b/drivers/vdpa/vdpa_sim/vdpa_sim_blk.c
>@@ -204,6 +204,9 @@ static void vdpasim_blk_work(struct work_struct *work)
> 	if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
> 		goto out;
>
>+	if (!vdpasim->running)
>+		goto out;
>+
> 	for (i = 0; i < VDPASIM_BLK_VQ_NUM; i++) {
> 		struct vdpasim_virtqueue *vq = &vdpasim->vqs[i];
>
>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;
>+
> 	if (!(vdpasim->status & VIRTIO_CONFIG_S_DRIVER_OK))
> 		goto out;
>
>-- 
>2.31.1
>