linux-kernel - [PATCH v4 3/4] vhost-vdpa: uAPI to stop the device

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Message-Id: <20220526124338.36247-4-eperezma@redhat.com>
Date:   Thu, 26 May 2022 14:43:37 +0200
From:   Eugenio Pérez <eperezma@...hat.com>
To:     "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
Cc:     martinh@...inx.com, Stefano Garzarella <sgarzare@...hat.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: [PATCH v4 3/4] vhost-vdpa: uAPI to stop the device

The ioctl adds support for stop the device from userspace.

Signed-off-by: Eugenio Pérez <eperezma@...hat.com>
---
 drivers/vhost/vdpa.c       | 18 ++++++++++++++++++
 include/uapi/linux/vhost.h | 14 ++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 32713db5831d..d1d19555c4b7 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c
@@ -478,6 +478,21 @@ static long vhost_vdpa_get_vqs_count(struct vhost_vdpa *v, u32 __user *argp)
 	return 0;
 }
 
+static long vhost_vdpa_stop(struct vhost_vdpa *v, u32 __user *argp)
+{
+	struct vdpa_device *vdpa = v->vdpa;
+	const struct vdpa_config_ops *ops = vdpa->config;
+	int stop;
+
+	if (!ops->stop)
+		return -EOPNOTSUPP;
+
+	if (copy_from_user(&stop, argp, sizeof(stop)))
+		return -EFAULT;
+
+	return ops->stop(vdpa, stop);
+}
+
 static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd,
 				   void __user *argp)
 {
@@ -650,6 +665,9 @@ 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_STOP:
+		r = vhost_vdpa_stop(v, argp);
+		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..c7e47b29bf61 100644
--- a/include/uapi/linux/vhost.h
+++ b/include/uapi/linux/vhost.h
@@ -171,4 +171,18 @@
 #define VHOST_VDPA_SET_GROUP_ASID	_IOW(VHOST_VIRTIO, 0x7C, \
 					     struct vhost_vring_state)
 
+/* Stop or resume a device so it does not process virtqueue requests anymore
+ *
+ * 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).
+ */
+#define VHOST_VDPA_STOP			_IOW(VHOST_VIRTIO, 0x7D, int)
+
 #endif
-- 
2.31.1