Date:   Fri, 26 Apr 2019 15:01:27 +0200
From:   Pierre Morel <pmorel@...ux.ibm.com>
To:     borntraeger@...ibm.com
Cc:     alex.williamson@...hat.com, cohuck@...hat.com,
        linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, frankja@...ux.ibm.com, akrowiak@...ux.ibm.com,
        pasic@...ux.ibm.com, david@...hat.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, freude@...ux.ibm.com, mimu@...ux.ibm.com
Subject: [PATCH v7 3/4] s390: ap: implement PAPQ AQIC interception in kernel

We register the AP PQAP instruction hook during the open
of the mediated device. And unregister it on release.

In the AP PQAP instruction hook, if we receive a demand to
enable IRQs,
- we retrieve the vfio_ap_queue based on the APQN we receive
  in REG1,
- we retrieve the page of the guest address, (NIB), from
  register REG2
- we the mediated device to use the VFIO pinning infratrsucture
  to pin the page of the guest address,
- we retrieve the pointer to KVM to register the guest ISC
  and retrieve the host ISC
- finaly we activate GISA

If we receive a demand to disable IRQs,
- we deactivate GISA
- unregister from the GIB
- unping the NIB

Signed-off-by: Pierre Morel <pmorel@...ux.ibm.com>
---
 drivers/s390/crypto/ap_bus.h          |   1 +
 drivers/s390/crypto/vfio_ap_drv.c     |  30 +++-
 drivers/s390/crypto/vfio_ap_ops.c     | 293 +++++++++++++++++++++++++++++++++-
 drivers/s390/crypto/vfio_ap_private.h |  11 ++
 4 files changed, 328 insertions(+), 7 deletions(-)

diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h
index 15a98a6..60e70f3 100644
--- a/drivers/s390/crypto/ap_bus.h
+++ b/drivers/s390/crypto/ap_bus.h
@@ -43,6 +43,7 @@ static inline int ap_test_bit(unsigned int *ptr, unsigned int nr)
 #define AP_RESPONSE_BUSY		0x05
 #define AP_RESPONSE_INVALID_ADDRESS	0x06
 #define AP_RESPONSE_OTHERWISE_CHANGED	0x07
+#define AP_RESPONSE_INVALID_GISA	0x08
 #define AP_RESPONSE_Q_FULL		0x10
 #define AP_RESPONSE_NO_PENDING_REPLY	0x10
 #define AP_RESPONSE_INDEX_TOO_BIG	0x11
diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index e9824c3..ecaa4ab 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@...ux.ibm.com>
+ *	      Pierre Morel <pmorel@...ux.ibm.com>
  */
 
 #include <linux/module.h>
@@ -40,14 +41,41 @@ static struct ap_device_id ap_queue_ids[] = {
 
 MODULE_DEVICE_TABLE(vfio_ap, ap_queue_ids);
 
+/**
+ * vfio_ap_queue_dev_probe:
+ *
+ * Allocate a vfio_ap_queue structure and associate it
+ * with the device as driver_data.
+ */
 static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
 {
+	struct vfio_ap_queue *q;
+
+	q = kzalloc(sizeof(*q), GFP_KERNEL);
+	if (!q)
+		return -ENOMEM;
+	dev_set_drvdata(&apdev->device, q);
+	q->apqn = to_ap_queue(&apdev->device)->qid;
+	q->a_isc = VFIO_AP_ISC_INVALID;
+	q->p_isc = VFIO_AP_ISC_INVALID;
 	return 0;
 }
 
+/**
+ * vfio_ap_queue_dev_remove:
+ *
+ * Takes the matrix lock to avoid actions on this device while removing
+ * Free the associated vfio_ap_queue structure
+ */
 static void vfio_ap_queue_dev_remove(struct ap_device *apdev)
 {
-	/* Nothing to do yet */
+	struct vfio_ap_queue *q;
+
+	mutex_lock(&matrix_dev->lock);
+	q = dev_get_drvdata(&apdev->device);
+	kfree(q);
+	dev_set_drvdata(&apdev->device, NULL);
+	mutex_unlock(&matrix_dev->lock);
 }
 
 static void vfio_ap_matrix_dev_release(struct device *dev)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index e8e87bf..c22b996 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -24,6 +24,252 @@
 #define VFIO_AP_MDEV_TYPE_HWVIRT "passthrough"
 #define VFIO_AP_MDEV_NAME_HWVIRT "VFIO AP Passthrough Device"
 
+static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev);
+
+static int match_apqn(struct device *dev, void *data)
+{
+	struct vfio_ap_queue *q = dev_get_drvdata(dev);
+
+	return (q->apqn == *(int *)(data)) ? 1 : 0;
+}
+
+/**
+ * vfio_ap_get_queue: Retrieve a queue with a specific APQN from a list
+ * @matrix_mdev: the associated mediated matrix
+ * @apqn: The queue APQN
+ *
+ * Retrieve a queue with a specific APQN from the list of the
+ * devices of the vfio_ap_drv.
+ * Verify that the APID and the APQI are set in the matrix.
+ *
+ * Returns the pointer to the associated vfio_ap_queue
+ */
+struct vfio_ap_queue *vfio_ap_get_queue(struct ap_matrix_mdev *matrix_mdev,
+					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);
+
+	return q;
+}
+
+/**
+ * vfio_ap_free_irq_data:
+ * @q: The vfio_ap_queue
+ *
+ * Unpin the guest NIB
+ * Unregister the ISC from the GIB alert
+ * Clear the vfio_ap_queue intern fields
+ *
+ * Important notice:
+ * Before calling this function, interrupt must have been
+ * unregistered by use of ap_zapq/ap_reset or ap_aqic.
+ */
+static void vfio_ap_free_irq_data(struct vfio_ap_queue *q)
+{
+	if (!q)
+		return;
+
+	if (q->a_isc != VFIO_AP_ISC_INVALID && q->matrix_mdev)
+		kvm_s390_gisc_unregister(q->matrix_mdev->kvm, q->a_isc);
+	if (q->a_pfn && q->matrix_mdev)
+		vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev), &q->a_pfn, 1);
+
+	q->a_pfn = 0;
+	q->p_pfn = 0;
+	q->a_isc = VFIO_AP_ISC_INVALID;
+	q->p_isc = VFIO_AP_ISC_INVALID;
+	q->matrix_mdev = NULL;
+}
+
+/**
+ * vfio_ap_clrirq: Disable Interruption for a APQN
+ *
+ * @dev: the device associated with the ap_queue
+ * @q:   the vfio_ap_queue holding AQIC parameters
+ *
+ * Issue the host side PQAP/AQIC
+ * On success: unpin the NIB saved in *q and unregister from GIB
+ * interface
+ *
+ * Return the ap_queue_status returned by the ap_aqic()
+ */
+static struct ap_queue_status vfio_ap_clrirq(struct vfio_ap_queue *q)
+{
+	struct ap_qirq_ctrl aqic_gisa = {};
+	struct ap_queue_status status;
+	int checks = 10;
+
+	status = ap_aqic(q->apqn, aqic_gisa, NULL);
+	if (!status.response_code) {
+		while (status.irq_enabled && checks--) {
+			msleep(20);
+			status = ap_tapq(q->apqn, NULL);
+		}
+		if (checks >= 0)
+			vfio_ap_free_irq_data(q);
+		else
+			WARN_ONCE("%s: failed disabling IRQ", __func__);
+	}
+
+	return status;
+}
+
+/**
+ * vfio_ap_setirq: Enable Interruption for a APQN
+ *
+ * @dev: the device associated with the ap_queue
+ * @q:   the vfio_ap_queue holding AQIC parameters
+ *
+ * Pin the NIB saved in *q
+ * Register the guest ISC to GIB interface and retrieve the
+ * host ISC to issue the host side PQAP/AQIC
+ *
+ * Response.status may be set to following Response Code in case of error:
+ * - AP_RESPONSE_INVALID_ADDRESS: vfio_pin_pages failed
+ * - AP_RESPONSE_OTHERWISE_CHANGED: Hypervizor GISA internal error
+ *
+ * Otherwise return the ap_queue_status returned by the ap_aqic()
+ */
+static struct ap_queue_status vfio_ap_setirq(struct vfio_ap_queue *q)
+{
+	struct ap_qirq_ctrl aqic_gisa = {};
+	struct ap_queue_status status = {};
+	struct kvm_s390_gisa *gisa;
+	struct kvm *kvm;
+	unsigned long h_nib, h_pfn;
+	int ret;
+
+	q->a_pfn = q->a_nib >> PAGE_SHIFT;
+	ret = vfio_pin_pages(mdev_dev(q->matrix_mdev->mdev), &q->a_pfn, 1,
+			     IOMMU_READ | IOMMU_WRITE, &h_pfn);
+	switch (ret) {
+	case 1:
+		break;
+	case -EINVAL:
+	case -E2BIG:
+		status.response_code = AP_RESPONSE_INVALID_ADDRESS;
+		/* Fallthrough */
+	default:
+		return status;
+	}
+
+	kvm = q->matrix_mdev->kvm;
+	gisa = kvm->arch.gisa_int.origin;
+
+	h_nib = (h_pfn << PAGE_SHIFT) | (q->a_nib & ~PAGE_MASK);
+	aqic_gisa.gisc = q->a_isc;
+	aqic_gisa.isc = kvm_s390_gisc_register(kvm, q->a_isc);
+	aqic_gisa.ir = 1;
+	aqic_gisa.gisa = gisa->next_alert >> 4;
+
+	status = ap_aqic(q->apqn, aqic_gisa, (void *)h_nib);
+	switch (status.response_code) {
+	case AP_RESPONSE_NORMAL:
+		/* See if we did clear older IRQ configuration */
+		if (q->p_pfn)
+			vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev),
+					 &q->p_pfn, 1);
+		if (q->p_isc != VFIO_AP_ISC_INVALID)
+			kvm_s390_gisc_unregister(kvm, q->p_isc);
+		q->p_pfn = q->a_pfn;
+		q->p_isc = q->a_isc;
+		break;
+	case AP_RESPONSE_OTHERWISE_CHANGED:
+		/* We could not modify IRQ setings: clear new configuration */
+		vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev), &q->a_pfn, 1);
+		kvm_s390_gisc_unregister(kvm, q->a_isc);
+		break;
+	default:	/* Fall Through */
+		pr_warn("%s: apqn %04x: response: %02x\n", __func__, q->apqn,
+			status.response_code);
+		vfio_ap_free_irq_data(q);
+		break;
+	}
+
+	return status;
+}
+
+/**
+ * handle_pqap: PQAP instruction callback
+ *
+ * @vcpu: The vcpu on which we received the PQAP instruction
+ *
+ * Get the general register contents to initialize internal variables.
+ * REG[0]: APQN
+ * REG[1]: IR and ISC
+ * REG[2]: NIB
+ *
+ * Response.status may be set to following Response Code:
+ * - AP_RESPONSE_Q_NOT_AVAIL: if the queue is not available
+ * - AP_RESPONSE_DECONFIGURED: if the queue is not configured
+ * - AP_RESPONSE_NORMAL (0) : in case of successs
+ *   Check vfio_ap_setirq() and vfio_ap_clrirq() for other possible RC.
+ * We take the matrix_dev lock to ensure serialization on queues and
+ * mediated device access.
+ *
+ * Return 0 if we could handle the request inside KVM.
+ * otherwise, returns -EOPNOTSUPP to let QEMU handle the fault.
+ */
+static int handle_pqap(struct kvm_vcpu *vcpu)
+{
+	uint64_t status;
+	uint16_t apqn;
+	struct vfio_ap_queue *q;
+	struct ap_queue_status qstatus = {
+			       .response_code = AP_RESPONSE_Q_NOT_AVAIL, };
+	struct ap_matrix_mdev *matrix_mdev;
+
+	/* If we do not use the AIV facility just go to userland */
+	if (!(vcpu->arch.sie_block->eca & ECA_AIV))
+		return -EOPNOTSUPP;
+
+	apqn = vcpu->run->s.regs.gprs[0] & 0xffff;
+	mutex_lock(&matrix_dev->lock);
+
+	if (!vcpu->kvm->arch.crypto.pqap_hook)
+		goto out_unlock;
+	matrix_mdev = container_of(vcpu->kvm->arch.crypto.pqap_hook,
+				   struct ap_matrix_mdev, pqap_hook);
+
+	q = vfio_ap_get_queue(matrix_mdev, apqn);
+	if (!q)
+		goto out_unlock;
+
+	status = vcpu->run->s.regs.gprs[1];
+
+	/* If IR bit(16) is set we enable the interrupt */
+	if ((status >> (63 - 16)) & 0x01) {
+		q->a_isc = status & 0x07;
+		q->a_nib = vcpu->run->s.regs.gprs[2];
+		qstatus = vfio_ap_setirq(q);
+		if (qstatus.response_code) {
+			q->a_nib = 0;
+			q->a_isc = VFIO_AP_ISC_INVALID;
+		}
+	} else
+		qstatus = vfio_ap_clrirq(q);
+
+out_unlock:
+	memcpy(&vcpu->run->s.regs.gprs[1], &qstatus, sizeof(qstatus));
+	vcpu->run->s.regs.gprs[1] >>= 32;
+	mutex_unlock(&matrix_dev->lock);
+	return 0;
+}
+
 static void vfio_ap_matrix_init(struct ap_config_info *info,
 				struct ap_matrix *matrix)
 {
@@ -45,8 +291,11 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
 		return -ENOMEM;
 	}
 
+	matrix_mdev->mdev = mdev;
 	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
 	mdev_set_drvdata(mdev, matrix_mdev);
+	matrix_mdev->pqap_hook.hook = handle_pqap;
+	matrix_mdev->pqap_hook.owner = THIS_MODULE;
 	mutex_lock(&matrix_dev->lock);
 	list_add(&matrix_mdev->node, &matrix_dev->mdev_list);
 	mutex_unlock(&matrix_dev->lock);
@@ -62,6 +311,7 @@ static int vfio_ap_mdev_remove(struct mdev_device *mdev)
 		return -EBUSY;
 
 	mutex_lock(&matrix_dev->lock);
+	vfio_ap_mdev_reset_queues(mdev);
 	list_del(&matrix_mdev->node);
 	mutex_unlock(&matrix_dev->lock);
 
@@ -754,6 +1004,8 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
 	}
 
 	matrix_mdev->kvm = kvm;
+	kvm_get_kvm(kvm);
+	kvm->arch.crypto.pqap_hook = &matrix_mdev->pqap_hook;
 	mutex_unlock(&matrix_dev->lock);
 
 	return 0;
@@ -819,15 +1071,37 @@ static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
 	return NOTIFY_OK;
 }
 
-static int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
-				    unsigned int retry)
+void vfio_ap_free_irq_data_apqn(int apqn)
+{
+	struct device *dev;
+	struct vfio_ap_queue *q;
+
+	dev = driver_find_device(&matrix_dev->vfio_ap_drv->driver, NULL,
+				 &apqn, match_apqn);
+	if (dev) {
+		q = dev_get_drvdata(dev);
+		vfio_ap_free_irq_data(q);
+		put_device(dev);
+	}
+}
+
+int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
+			     unsigned int retry)
 {
 	struct ap_queue_status status;
+	int retry2 = 2;
+	int apqn = AP_MKQID(apid, apqi);
 
 	do {
-		status = ap_zapq(AP_MKQID(apid, apqi));
+		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(retry <= 0);
+			vfio_ap_free_irq_data_apqn(apqn);
 			return 0;
 		case AP_RESPONSE_RESET_IN_PROGRESS:
 		case AP_RESPONSE_BUSY:
@@ -904,15 +1178,20 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev)
 {
 	struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
 
-	if (matrix_mdev->kvm)
+	mutex_lock(&matrix_dev->lock);
+	if (matrix_mdev->kvm) {
 		kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
+		matrix_mdev->kvm->arch.crypto.pqap_hook = NULL;
+		vfio_ap_mdev_reset_queues(mdev);
+		kvm_put_kvm(matrix_mdev->kvm);
+		matrix_mdev->kvm = NULL;
+	}
+	mutex_unlock(&matrix_dev->lock);
 
-	vfio_ap_mdev_reset_queues(mdev);
 	vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
 				 &matrix_mdev->iommu_notifier);
 	vfio_unregister_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY,
 				 &matrix_mdev->group_notifier);
-	matrix_mdev->kvm = NULL;
 	module_put(THIS_MODULE);
 }
 
@@ -941,6 +1220,7 @@ static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev,
 {
 	int ret;
 
+	mutex_lock(&matrix_dev->lock);
 	switch (cmd) {
 	case VFIO_DEVICE_GET_INFO:
 		ret = vfio_ap_mdev_get_device_info(arg);
@@ -952,6 +1232,7 @@ static ssize_t vfio_ap_mdev_ioctl(struct mdev_device *mdev,
 		ret = -EOPNOTSUPP;
 		break;
 	}
+	mutex_unlock(&matrix_dev->lock);
 
 	return ret;
 }
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 18dcc4d..7cc02ff 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@...ux.ibm.com>
  *	      Halil Pasic <pasic@...ux.ibm.com>
+ *	      Pierre Morel <pmorel@...ux.ibm.com>
  *
  * Copyright IBM Corp. 2018
  */
@@ -90,4 +91,14 @@ struct ap_matrix_mdev {
 extern int vfio_ap_mdev_register(void);
 extern void vfio_ap_mdev_unregister(void);
 
+struct vfio_ap_queue {
+	struct ap_matrix_mdev *matrix_mdev;
+	unsigned long a_nib;
+	unsigned long a_pfn;
+	unsigned long p_pfn;
+	int	apqn;
+#define VFIO_AP_ISC_INVALID 0xff
+	unsigned char a_isc;
+	unsigned char p_isc;
+};
 #endif /* _VFIO_AP_PRIVATE_H_ */
-- 
2.7.4

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