[PATCH RFC 5/8] vfio: ccw: realize VFIO_DEVICE_CCW_HOT_RESET ioctl

Dong Jia Shi
2016-04-29T12:11:52Z

Introduce VFIO_DEVICE_CCW_HOT_RESET ioctl for vfio-ccw to make it
possible to hot-reset the device.

We try to achieve a hot reset by first offlining the device and then
onlining it again: this should clear all state at the subchannel.

Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
Reviewed-by: Pierre Morel <pmorel@linux.vnet.ibm.com>
---
drivers/vfio/ccw/vfio_ccw.c | 50 ++++++++++++++++++++++++++++++++++++++++++++-
include/uapi/linux/vfio.h | 8 ++++++++
2 files changed, 57 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/ccw/vfio_ccw.c b/drivers/vfio/ccw/vfio_ccw.c
index 7331aed..9700448 100644
--- a/drivers/vfio/ccw/vfio_ccw.c
+++ b/drivers/vfio/ccw/vfio_ccw.c
@@ -22,10 +22,12 @@
* struct vfio_ccw_device
* @cdev: ccw device
* @going_away: if an offline procedure was already ongoing
+ * @hot_reset: if hot-reset is ongoing
*/
struct vfio_ccw_device {
struct ccw_device *cdev;
bool going_away;
+ bool hot_reset;
};

enum vfio_ccw_device_type {
@@ -58,6 +60,7 @@ static void vfio_ccw_release(void *device_data)
static long vfio_ccw_ioctl(void *device_data, unsigned int cmd,
unsigned long arg)
{
+ struct vfio_ccw_device *vcdev = device_data;
unsigned long minsz;

if (cmd == VFIO_DEVICE_GET_INFO) {
@@ -76,6 +79,34 @@ static long vfio_ccw_ioctl(void *device_data, unsigned int cmd,
info.num_irqs = 0;

return copy_to_user((void __user *)arg, &info, minsz);
+
+ } else if (cmd == VFIO_DEVICE_CCW_HOT_RESET) {
+ unsigned long flags;
+ int ret;
+
+ spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
+ if (!vcdev->cdev->online) {
+ spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev),
+ flags);
+ return -EINVAL;
+ }
+
+ if (vcdev->hot_reset) {
+ spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev),
+ flags);
+ return -EBUSY;
+ }
+ vcdev->hot_reset = true;
+ spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);
+
+ ret = ccw_device_set_offline(vcdev->cdev);
+ if (!ret)
+ ret = ccw_device_set_online(vcdev->cdev);
+
+ spin_lock_irqsave(get_ccwdev_lock(vcdev->cdev), flags);
+ vcdev->hot_reset = false;
+ spin_unlock_irqrestore(get_ccwdev_lock(vcdev->cdev), flags);
+ return ret;
}

return -ENOTTY;
@@ -108,7 +139,7 @@ static int vfio_ccw_set_offline(struct ccw_device *cdev)

vdev = vfio_device_data(device);
vfio_device_put(device);
- if (!vdev || vdev->going_away)
+ if (!vdev || vdev->hot_reset || vdev->going_away)
return 0;

vdev->going_away = true;
@@ -128,9 +159,26 @@ void vfio_ccw_remove(struct ccw_device *cdev)

static int vfio_ccw_set_online(struct ccw_device *cdev)
{
+ struct vfio_device *device = vfio_device_get_from_dev(&cdev->dev);
struct vfio_ccw_device *vdev;
int ret;

+ if (!device)
+ goto create_device;
+
+ vdev = vfio_device_data(device);
+ vfio_device_put(device);
+ if (!vdev)
+ goto create_device;
+
+ /*
+ * During hot reset, we just want to disable/enable the
+ * subchannel and need not setup anything again.
+ */
+ if (vdev->hot_reset)
+ return 0;
+
+create_device:
vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
if (!vdev)
return -ENOMEM;
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index aaedfcd..889a316 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -687,6 +687,14 @@ struct vfio_iommu_spapr_tce_remove {
};
#define VFIO_IOMMU_SPAPR_TCE_REMOVE _IO(VFIO_TYPE, VFIO_BASE + 20)

+/**
+ * VFIO_DEVICE_CCW_HOT_RESET - _IOW(VFIO_TYPE, VFIO_BASE + 21)
+ *
+ * Hot reset the channel I/O device. All state of the subchannel will be
+ * cleared.
+ */
+#define VFIO_DEVICE_CCW_HOT_RESET _IO(VFIO_TYPE, VFIO_BASE + 21)
+
/* ***************************************************************** */

#endif /* _UAPIVFIO_H */
--
2.6.6