[PATCH v13 02/15] s390/vfio-ap: No need to disable IRQ after queue reset

Tony Krowiak
2020-12-23T01:17:06Z

The queues assigned to a matrix mediated device are currently reset when:

* The VFIO_DEVICE_RESET ioctl is invoked
* The mdev fd is closed by userspace (QEMU)
* The mdev is removed from sysfs.

Immediately after the reset of a queue, a call is made to disable
interrupts for the queue. This is entirely unnecessary because the reset of
a queue disables interrupts, so this will be removed.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
---
drivers/s390/crypto/vfio_ap_drv.c | 1 -
drivers/s390/crypto/vfio_ap_ops.c | 40 +++++++++++++++++----------
drivers/s390/crypto/vfio_ap_private.h | 1 -
3 files changed, 26 insertions(+), 16 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index be2520cc010b..ca18c91afec9 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -79,7 +79,6 @@ static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
apid = AP_QID_CARD(q->apqn);
apqi = AP_QID_QUEUE(q->apqn);
vfio_ap_mdev_reset_queue(apid, apqi, 1);
- vfio_ap_irq_disable(q);
kfree(q);
mutex_unlock(&matrix_dev->lock);
}
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 7339043906cf..052f61391ec7 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -25,6 +25,7 @@
#define VFIO_AP_MDEV_NAME_HWVIRT "VFIO AP Passthrough Device"

static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev);
+static struct vfio_ap_queue *vfio_ap_find_queue(int apqn);

static int match_apqn(struct device *dev, const void *data)
{
@@ -49,20 +50,15 @@ static struct vfio_ap_queue *vfio_ap_get_queue(
int apqn)
{
struct vfio_ap_queue *q;
- struct device *dev;

if (!test_bit_inv(AP_QID_CARD(apqn), matrix_mdev->matrix.apm))
return NULL;
if (!test_bit_inv(AP_QID_QUEUE(apqn), matrix_mdev->matrix.aqm))
return NULL;

- dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
- &apqn, match_apqn);
- if (!dev)
- return NULL;
- q = dev_get_drvdata(dev);
- q->matrix_mdev = matrix_mdev;
- put_device(dev);
+ q = vfio_ap_find_queue(apqn);
+ if (q)
+ q->matrix_mdev = matrix_mdev;

return q;
}
@@ -1126,24 +1122,27 @@ static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
return notify_rc;
}

-static void vfio_ap_irq_disable_apqn(int apqn)
+static struct vfio_ap_queue *vfio_ap_find_queue(int apqn)
{
struct device *dev;
- struct vfio_ap_queue *q;
+ struct vfio_ap_queue *q = NULL;

dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
&apqn, match_apqn);
if (dev) {
q = dev_get_drvdata(dev);
- vfio_ap_irq_disable(q);
put_device(dev);
}
+
+ return q;
}

int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
unsigned int retry)
{
struct ap_queue_status status;
+ struct vfio_ap_queue *q;
+ int ret;
int retry2 = 2;
int apqn = AP_MKQID(apid, apqi);

@@ -1156,18 +1155,32 @@ int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
status = ap_tapq(apqn, NULL);
}
WARN_ON_ONCE(retry2 <= 0);
- return 0;
+ ret = 0;
+ goto free_aqic_resources;
case AP_RESPONSE_RESET_IN_PROGRESS:
case AP_RESPONSE_BUSY:
msleep(20);
break;
default:
/* things are really broken, give up */
- return -EIO;
+ ret = -EIO;
+ goto free_aqic_resources;
}
} while (retry--);

return -EBUSY;
+
+free_aqic_resources:
+ /*
+ * In order to free the aqic resources, the queue must be linked to
+ * the matrix_mdev to which its APQN is assigned and the KVM pointer
+ * must be available.
+ */
+ q = vfio_ap_find_queue(apqn);
+ if (q && q->matrix_mdev && q->matrix_mdev->kvm)
+ vfio_ap_free_aqic_resources(q);
+
+ return ret;
}

static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev)
@@ -1189,7 +1202,6 @@ static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev)
*/
if (ret)
rc = ret;
- vfio_ap_irq_disable_apqn(AP_MKQID(apid, apqi));
}
}

diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index f46dde56b464..0db6fb3d56d5 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -100,5 +100,4 @@ struct vfio_ap_queue {
#define VFIO_AP_ISC_INVALID 0xff
unsigned char saved_isc;
};
-struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q);
#endif /* _VFIO_AP_PRIVATE_H_ */
--
2.21.1