[PATCH 5.10 030/142] s390/vfio-ap: No need to disable IRQ after queue reset

Greg Kroah-Hartman
2021-02-02T13:51:24Z

From: Tony Krowiak <akrowiak@linux.ibm.com>

commit 6c12a6384e0c0b96debd88b24028e58f2ebd417b upstream.

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.

Furthermore, vfio_ap_irq_disable() does an unconditional PQAP/AQIC which
can result in a specification exception (when the corresponding facility
is not available), so this is actually a bugfix.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
[pasic@linux.ibm.com: minor rework before merging]
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Fixes: ec89b55e3bce ("s390: ap: implement PAPQ AQIC interception in kernel")
Cc: <stable@vger.kernel.org>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/s390/crypto/vfio_ap_drv.c | 6 --
drivers/s390/crypto/vfio_ap_ops.c | 100 +++++++++++++++++++++-------------
drivers/s390/crypto/vfio_ap_private.h | 12 ++--
3 files changed, 69 insertions(+), 49 deletions(-)

--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -71,15 +71,11 @@ static int vfio_ap_queue_dev_probe(struc
static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
{
struct vfio_ap_queue *q;
- int apid, apqi;

mutex_lock(&matrix_dev->lock);
q = dev_get_drvdata(&apdev->device);
+ vfio_ap_mdev_reset_queue(q, 1);
dev_set_drvdata(&apdev->device, NULL);
- 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);
}
--- 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
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;
}
@@ -119,13 +115,18 @@ static void vfio_ap_wait_for_irqclear(in
*/
static void vfio_ap_free_aqic_resources(struct vfio_ap_queue *q)
{
- if (q->saved_isc != VFIO_AP_ISC_INVALID && q->matrix_mdev)
+ if (!q)
+ return;
+ if (q->saved_isc != VFIO_AP_ISC_INVALID &&
+ !WARN_ON(!(q->matrix_mdev && q->matrix_mdev->kvm))) {
kvm_s390_gisc_unregister(q->matrix_mdev->kvm, q->saved_isc);
- if (q->saved_pfn && q->matrix_mdev)
+ q->saved_isc = VFIO_AP_ISC_INVALID;
+ }
+ if (q->saved_pfn && !WARN_ON(!q->matrix_mdev)) {
vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev),
&q->saved_pfn, 1);
- q->saved_pfn = 0;
- q->saved_isc = VFIO_AP_ISC_INVALID;
+ q->saved_pfn = 0;
+ }
}

/**
@@ -144,7 +145,7 @@ static void vfio_ap_free_aqic_resources(
* Returns if ap_aqic function failed with invalid, deconfigured or
* checkstopped AP.
*/
-struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
+static struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q)
{
struct ap_qirq_ctrl aqic_gisa = {};
struct ap_queue_status status;
@@ -1114,48 +1115,70 @@ static int vfio_ap_mdev_group_notifier(s
return NOTIFY_OK;
}

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

- do {
- status = ap_zapq(apqn);
- switch (status.response_code) {
- case AP_RESPONSE_NORMAL:
- while (!status.queue_empty && retry2--) {
- msleep(20);
- status = ap_tapq(apqn, NULL);
- }
- WARN_ON_ONCE(retry2 <= 0);
- return 0;
- case AP_RESPONSE_RESET_IN_PROGRESS:
- case AP_RESPONSE_BUSY:
+ if (!q)
+ return 0;
+
+retry_zapq:
+ status = ap_zapq(q->apqn);
+ switch (status.response_code) {
+ case AP_RESPONSE_NORMAL:
+ ret = 0;
+ break;
+ case AP_RESPONSE_RESET_IN_PROGRESS:
+ if (retry--) {
msleep(20);
- break;
- default:
- /* things are really broken, give up */
- return -EIO;
+ goto retry_zapq;
}
- } while (retry--);
+ ret = -EBUSY;
+ break;
+ case AP_RESPONSE_Q_NOT_AVAIL:
+ case AP_RESPONSE_DECONFIGURED:
+ case AP_RESPONSE_CHECKSTOPPED:
+ WARN_ON_ONCE(status.irq_enabled);
+ ret = -EBUSY;
+ goto free_resources;
+ default:
+ /* things are really broken, give up */
+ WARN(true, "PQAP/ZAPQ completed with invalid rc (%x)\n",
+ status.response_code);
+ return -EIO;
+ }
+
+ /* wait for the reset to take effect */
+ while (retry2--) {
+ if (status.queue_empty && !status.irq_enabled)
+ break;
+ msleep(20);
+ status = ap_tapq(q->apqn, NULL);
+ }
+ WARN_ON_ONCE(retry2 <= 0);

- return -EBUSY;
+free_resources:
+ vfio_ap_free_aqic_resources(q);
+
+ return ret;
}

static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev)
@@ -1163,13 +1186,15 @@ static int vfio_ap_mdev_reset_queues(str
int ret;
int rc = 0;
unsigned long apid, apqi;
+ struct vfio_ap_queue *q;
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);

for_each_set_bit_inv(apid, matrix_mdev->matrix.apm,
matrix_mdev->matrix.apm_max + 1) {
for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
matrix_mdev->matrix.aqm_max + 1) {
- ret = vfio_ap_mdev_reset_queue(apid, apqi, 1);
+ q = vfio_ap_find_queue(AP_MKQID(apid, apqi));
+ ret = vfio_ap_mdev_reset_queue(q, 1);
/*
* Regardless whether a queue turns out to be busy, or
* is not operational, we need to continue resetting
@@ -1177,7 +1202,6 @@ static int vfio_ap_mdev_reset_queues(str
*/
if (ret)
rc = ret;
- vfio_ap_irq_disable_apqn(AP_MKQID(apid, apqi));
}
}

--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -88,11 +88,6 @@ struct ap_matrix_mdev {
struct mdev_device *mdev;
};

-extern int vfio_ap_mdev_register(void);
-extern void vfio_ap_mdev_unregister(void);
-int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
- unsigned int retry);
-
struct vfio_ap_queue {
struct ap_matrix_mdev *matrix_mdev;
unsigned long saved_pfn;
@@ -100,5 +95,10 @@ 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);
+
+int vfio_ap_mdev_register(void);
+void vfio_ap_mdev_unregister(void);
+int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q,
+ unsigned int retry);
+
#endif /* _VFIO_AP_PRIVATE_H_ */