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Message-ID: <19d8a764-fd48-ebe0-ec38-cf201fb53a3e@de.ibm.com>
Date: Fri, 22 Jan 2021 09:24:27 +0100
From: Christian Borntraeger <borntraeger@...ibm.com>
To: Halil Pasic <pasic@...ux.ibm.com>,
Tony Krowiak <akrowiak@...ux.ibm.com>,
linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
kvm@...r.kernel.org
Cc: stable@...r.kernel.org, Pierre Morel <pmorel@...ux.ibm.com>,
Harald Freudenberger <freude@...ux.ibm.com>,
Heiko Carstens <hca@...ux.ibm.com>,
Vasily Gorbik <gor@...ux.ibm.com>, mjrosato@...ux.ibm.com,
alex.williamson@...hat.com, kwankhede@...dia.com,
fiuczy@...ux.ibm.com, frankja@...ux.ibm.com, david@...hat.com
Subject: Re: [PATCH 1/1] s390/vfio-ap: No need to disable IRQ after queue
reset
On 21.01.21 08:20, Halil Pasic wrote:
> From: Tony Krowiak <akrowiak@...ux.ibm.com>
>
> 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@...ux.ibm.com>
> [pasic@...ux.ibm.com: minor rework before merging]
> Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>
> Signed-off-by: Halil Pasic <pasic@...ux.ibm.com>
> Fixes: ec89b55e3bce ("s390: ap: implement PAPQ AQIC interception in kernel")
> Cc: <stable@...r.kernel.org>
Acked-by: Christian Borntraeger <borntraeger@...ibm.com>
Heiko, Vasily, lets carry this via the s390 tree.
>
> ---
>
> Since it turned out disabling the interrupts via PQAP/AQIC is not only
> unnecesary but also buggy, we decided to put this patch, which
> used to be apart of the series https://lkml.org/lkml/2020/12/22/757 on the fast
> lane.
>
> If the backports turn out to be a bother, which I hope won't be the case
> not, I am happy to help with those.
>
> ---
> 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(-)
>
> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> index be2520cc010b..7dc72cb718b0 100644
> --- 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(struct ap_device *apdev)
> 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);
> }
> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
> index e0bde8518745..7ceb6c433b3b 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;
> }
> @@ -119,13 +115,18 @@ static void vfio_ap_wait_for_irqclear(int apqn)
> */
> 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(struct vfio_ap_queue *q)
> * 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(struct notifier_block *nb,
> 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(struct mdev_device *mdev)
> 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(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..28e9d9989768 100644
> --- 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_ */
>
> base-commit: 9791581c049c10929e97098374dd1716a81fefcc
>
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