Re: [PATCH v4 6/7] s390: ap: Cleanup on removing the AP device

Tony Krowiak
2019-03-08T22:43:56Z

On 2/22/19 10:29 AM, Pierre Morel wrote:
> 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 | 35 +++++++++++++++++++++++++++++++++++
> drivers/s390/crypto/vfio_ap_ops.c | 3 ++-
> drivers/s390/crypto/vfio_ap_private.h | 3 +++
> 3 files changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> index eca0ffc..e5d91ff 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"
> @@ -61,6 +64,33 @@ static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
> }
>
> /**
> + * 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_mdev;
> +
> + 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:
> *
> * Free the associated vfio_ap_queue structure
> @@ -70,6 +100,11 @@ 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_mdev_reset_queue(q);

Since the bit corresponding to the APID is cleared in the
vfio_ap_update_crycb() above, shouldn't all queues on that
card also be reset?

> list_del(&q->list);
> kfree(q);
> }
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index 0196065..5b9bb33 100644
> --- a/drivers/s390/crypto/vfio_ap_ops.c
> +++ b/drivers/s390/crypto/vfio_ap_ops.c
> @@ -59,6 +59,7 @@ int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q)
> if (retry <= 0)
> pr_warn("%s: queue 0x%04x not empty\n",
> __func__, q->apqn);
> + vfio_ap_free_irq(q);

Shouldn't this be done for the response codes that terminate this loop
such as those caught by the default case?

> return 0;
> case AP_RESPONSE_RESET_IN_PROGRESS:
> case AP_RESPONSE_BUSY:
> @@ -83,7 +84,7 @@ int vfio_ap_mdev_reset_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)
> {
> if (!q)
> return;
> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> index e2fd2c0..cc18215 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
> */
> @@ -98,4 +99,6 @@ struct vfio_ap_queue {
> int apqn;
> unsigned char isc;
> };
> +void vfio_ap_free_irq(struct vfio_ap_queue *q);
> +int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q);
> #endif /* _VFIO_AP_PRIVATE_H_ */
>