[PATCH v4 10/16] vfio: ccw: realize VFIO_DEVICE_RESET ioctl

Dong Jia Shi
2017-03-17T03:17:37Z

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

We try to achieve a reset by first disabling the subchannel and
then enabling it again: this should clear all state at the subchannel.

Signed-off-by: Dong Jia Shi <bjsdjshi@linux.vnet.ibm.com>
---
drivers/s390/cio/vfio_ccw_ops.c | 47 +++++++++++++++++++++++++++++------------
1 file changed, 33 insertions(+), 14 deletions(-)

diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c
index f3300dd..125818c 100644
--- a/drivers/s390/cio/vfio_ccw_ops.c
+++ b/drivers/s390/cio/vfio_ccw_ops.c
@@ -12,6 +12,32 @@

#include "vfio_ccw_private.h"

+static int vfio_ccw_mdev_reset(struct mdev_device *mdev)
+{
+ struct vfio_ccw_private *private;
+ struct subchannel *sch;
+ int ret;
+
+ private = dev_get_drvdata(mdev_parent_dev(mdev));
+ if (!private)
+ return -ENODEV;
+
+ sch = private->sch;
+ /*
+ * TODO:
+ * In the cureent stage, some things like "no I/O running" and "no
+ * interrupt pending" are clear, but we are not sure what other state
+ * we need to care about.
+ * There are still a lot more instructions need to be handled. We
+ * should come back here later.
+ */
+ ret = vfio_ccw_sch_quiesce(sch);
+ if (ret)
+ return ret;
+
+ return cio_enable_subchannel(sch, (u32)(unsigned long)sch);
+}
+
static int vfio_ccw_mdev_notifier(struct notifier_block *nb,
unsigned long action,
void *data)
@@ -28,15 +54,11 @@ static int vfio_ccw_mdev_notifier(struct notifier_block *nb,
*/
if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP) {
struct vfio_iommu_type1_dma_unmap *unmap = data;
- struct subchannel *sch = private->sch;

if (!cp_iova_pinned(&private->cp, unmap->iova))
return NOTIFY_OK;

- if (vfio_ccw_sch_quiesce(sch))
- return NOTIFY_BAD;
-
- if (cio_enable_subchannel(sch, (u32)(unsigned long)sch))
+ if (vfio_ccw_mdev_reset(private->mdev))
return NOTIFY_BAD;

cp_free(&private->cp);
@@ -100,16 +122,11 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev)

static int vfio_ccw_mdev_remove(struct mdev_device *mdev)
{
- struct vfio_ccw_private *private;
- struct subchannel *sch;
+ struct vfio_ccw_private *private =
+ dev_get_drvdata(mdev_parent_dev(mdev));
int ret;

- private = dev_get_drvdata(mdev_parent_dev(mdev));
- sch = private->sch;
- ret = vfio_ccw_sch_quiesce(sch);
- if (ret)
- return ret;
- ret = cio_enable_subchannel(sch, (u32)(unsigned long)sch);
+ ret = vfio_ccw_mdev_reset(mdev);
if (ret)
return ret;

@@ -190,7 +207,7 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev,

static int vfio_ccw_mdev_get_device_info(struct vfio_device_info *info)
{
- info->flags = VFIO_DEVICE_FLAGS_CCW;
+ info->flags = VFIO_DEVICE_FLAGS_CCW | VFIO_DEVICE_FLAGS_RESET;
info->num_regions = VFIO_CCW_NUM_REGIONS;
info->num_irqs = 0;

@@ -260,6 +277,8 @@ static ssize_t vfio_ccw_mdev_ioctl(struct mdev_device *mdev,

return copy_to_user((void __user *)arg, &info, minsz);
}
+ case VFIO_DEVICE_RESET:
+ return vfio_ccw_mdev_reset(mdev);
default:
return -ENOTTY;
}
--
2.8.4