[PATCH v3 8/9] s390: ap: Cleanup on removing the AP device

Pierre Morel
2019-02-14T13:51:49Z

When the device is remove, we must make sure to
clear the interruption and reset the AP device.

We also need to clear the CRYCB of the guest.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
drivers/s390/crypto/vfio_ap_drv.c | 92 +++++++++++++++++++++++++++++++++++
drivers/s390/crypto/vfio_ap_ops.c | 2 +-
drivers/s390/crypto/vfio_ap_private.h | 2 +
3 files changed, 95 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index 03153e6..50428be 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -5,6 +5,7 @@
* Copyright IBM Corp. 2018
*
* Author(s): Tony Krowiak <akrowiak@linux.ibm.com>
+ * Pierre Morel <pmorel@linux.ibm.com>
*/

#include <linux/module.h>
@@ -12,6 +13,8 @@
#include <linux/slab.h>
#include <linux/string.h>
#include <asm/facility.h>
+#include <linux/bitops.h>
+#include <linux/kvm_host.h>
#include "vfio_ap_private.h"

#define VFIO_AP_ROOT_NAME "vfio_ap"
@@ -64,6 +67,88 @@ static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
return 0;
}

+/*
+ * vfio_ap_drain_queue
+ * @q: the queue to drain
+ *
+ * This function waits until the queue is empty.
+ */
+static void vfio_ap_drain_queue(struct vfio_ap_queue *q)
+{
+ struct ap_queue_status status;
+ int retry = 20;
+
+ status = ap_tapq(q->apqn, NULL);
+ while (!status.queue_empty && retry--) {
+ msleep(200);
+ status = ap_tapq(q->apqn, NULL);
+ }
+ if (retry <= 0) {
+ pr_warn("%s: queue not empty after zapq on apqn 0x%04x\n",
+ __func__, q->apqn);
+ }
+}
+
+/*
+ * vfio_ap_zapq
+ * @q: The queue to zerro
+ *
+ * It is best effort, no return value is done, however on success
+ * we will drain the queue before getting the queue back to the
+ * AP bus.
+ */
+static void vfio_ap_zapq(struct vfio_ap_queue *q)
+{
+ struct ap_queue_status status;
+ int retry = 20;
+
+ do {
+ status = ap_zapq(q->apqn);
+ switch (status.response_code) {
+ case AP_RESPONSE_RESET_IN_PROGRESS:
+ case AP_RESPONSE_BUSY:
+ msleep(20);
+ break;
+ default:
+ pr_warn("%s: zapq error %02x on apqn 0x%04x\n",
+ __func__, status.response_code, q->apqn);
+ return;
+ case AP_RESPONSE_NORMAL:
+ vfio_ap_drain_queue(q);
+ return;
+ }
+ } while (retry--);
+ pr_warn("%s: zapq retry count exceeded code %02x on apqn 0x%04x\n",
+ __func__, status.response_code, q->apqn);
+}
+
+/**
+ * vfio_ap_update_crycb
+ * @q: A pointer to the queue being removed
+ *
+ * We clear the APID of the queue, making this queue unusable for the guest.
+ * After this function we can reset the queue without to fear a race with
+ * the guest to access the queue again.
+ * We do not fear race with the host as we still get the device.
+ */
+static void vfio_ap_update_crycb(struct vfio_ap_queue *q)
+{
+ struct ap_matrix_mdev *matrix_mdev = q->matrix;
+
+ if (!matrix_mdev)
+ return;
+
+ clear_bit_inv(AP_QID_CARD(q->apqn), matrix_mdev->matrix.apm);
+
+ if (!matrix_mdev->kvm)
+ return;
+
+ kvm_arch_crypto_set_masks(matrix_mdev->kvm,
+ matrix_mdev->matrix.apm,
+ matrix_mdev->matrix.aqm,
+ matrix_mdev->matrix.adm);
+}
+
/**
* vfio_ap_queue_dev_remove:
*
@@ -74,6 +159,13 @@ static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
struct vfio_ap_queue *q;

q = dev_get_drvdata(&apdev->device);
+ if (!q)
+ return;
+
+ vfio_ap_update_crycb(q);
+ vfio_ap_zapq(q);
+
+ vfio_ap_free_irq(q);
kfree(q);
}

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 5664cf3..7ec957c 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -85,7 +85,7 @@ static void vfio_ap_put_queue(struct vfio_ap_queue *q)
* Unregister the ISC from the GIB alert
* Clear the vfio_ap_queue intern fields
*/
-static void vfio_ap_free_irq(struct vfio_ap_queue *q)
+void vfio_ap_free_irq(struct vfio_ap_queue *q)
{
unsigned long pfn = q->nib >> PAGE_SHIFT;

diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 16c99e9..d108c6d 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -4,6 +4,7 @@
*
* Author(s): Tony Krowiak <akrowiak@linux.ibm.com>
* Halil Pasic <pasic@linux.ibm.com>
+ * Pierre Morel <pmorel@linux.ibm.com>
*
* Copyright IBM Corp. 2018
*/
@@ -95,4 +96,5 @@ struct vfio_ap_queue {
unsigned long nib;
unsigned char isc;
};
+void vfio_ap_free_irq(struct vfio_ap_queue *q);
#endif /* _VFIO_AP_PRIVATE_H_ */
--
2.7.4