Date:   Thu, 14 Feb 2019 14:51:07 +0100
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 v3 7/9] 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_ops.c     | 191 +++++++++++++++++++++++++++++++++-
 drivers/s390/crypto/vfio_ap_private.h |   2 +
 3 files changed, 191 insertions(+), 3 deletions(-)

diff --git a/drivers/s390/crypto/ap_bus.h b/drivers/s390/crypto/ap_bus.h
index bfc66e4..323f2aa 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_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 6eddc2c..5664cf3 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -77,6 +77,28 @@ static void vfio_ap_put_queue(struct vfio_ap_queue *q)
 	q->dev = NULL;
 }
 
+/**
+ * vfio_ap_free_irq:
+ * @q: The vfio_ap_queue
+ *
+ * Unpin the guest NIB
+ * 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)
+{
+	unsigned long pfn = q->nib >> PAGE_SHIFT;
+
+	if (!q)
+		return;
+	if (q->nib)
+		vfio_unpin_pages(mdev_dev(q->matrix->mdev), &pfn, 1);
+	if (q->isc)
+		kvm_s390_gisc_unregister(q->matrix->kvm, q->isc);
+	q->nib = 0;
+	q->isc = 0;
+}
+
 static void vfio_ap_matrix_init(struct ap_config_info *info,
 				struct ap_matrix *matrix)
 {
@@ -98,6 +120,7 @@ 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);
 	mutex_lock(&matrix_dev->lock);
@@ -781,6 +804,156 @@ static const struct attribute_group *vfio_ap_mdev_attr_groups[] = {
 };
 
 /**
+ * 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;
+
+	status = ap_aqic(q->apqn, aqic_gisa, NULL);
+	if (!status.response_code)
+		vfio_ap_free_irq(q);
+
+	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 g_pfn, h_nib, h_pfn;
+	int ret;
+
+	kvm = q->matrix->kvm;
+	gisa = kvm->arch.gisa_int.origin;
+
+	g_pfn = q->nib >> PAGE_SHIFT;
+	ret = vfio_pin_pages(mdev_dev(q->matrix->mdev), &g_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;
+	}
+
+	h_nib = (h_pfn << PAGE_SHIFT) | (q->nib & ~PAGE_MASK);
+	aqic_gisa.gisc = q->isc;
+	aqic_gisa.isc = kvm_s390_gisc_register(kvm, q->isc);
+	aqic_gisa.ir = 1;
+	aqic_gisa.gisa = gisa->next_alert >> 4;
+
+	status = ap_aqic(q->apqn, aqic_gisa, (void *)h_nib);
+	if (status.response_code == AP_RESPONSE_INVALID_GISA) {
+		status.response_code = AP_RESPONSE_OTHERWISE_CHANGED;
+		pr_warn("vfio_ap: apqn %02x.%04x: AP_RESPONSE_INVALID_GISA\n",
+			(q->apqn >> 8) & 0xff, q->apqn & 0xff);
+	}
+
+	if (status.response_code)
+		vfio_ap_free_irq(q);
+
+	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.
+ *
+ * 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 = {};
+	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;
+	q = vfio_ap_get_queue(apqn);
+	if (!q) {
+		qstatus.response_code = AP_RESPONSE_Q_NOT_AVAIL;
+		goto out;
+	}
+
+	/* Check if the queue is associated with a guest matrix */
+	matrix_mdev = q->matrix;
+	if (!matrix_mdev || !matrix_mdev->kvm) {
+		qstatus.response_code = AP_RESPONSE_DECONFIGURED;
+		goto out;
+	}
+
+	status = vcpu->run->s.regs.gprs[1];
+
+	/* If IR bit(16) is set we enable the interrupt */
+	if ((status >> (63 - 16)) & 0x01) {
+		q->isc = status & 0x07;
+		q->nib = vcpu->run->s.regs.gprs[2];
+		qstatus = vfio_ap_setirq(q);
+		if (qstatus.response_code) {
+			q->nib = 0;
+			q->isc = 0;
+		}
+	} else
+		qstatus = vfio_ap_clrirq(q);
+
+out:
+	memcpy(&vcpu->run->s.regs.gprs[1], &qstatus, sizeof(qstatus));
+	vfio_ap_put_queue(q);
+	return 0;
+}
+
+ /*
  * vfio_ap_mdev_iommu_notifier: IOMMU notifier callback
  *
  * @nb: The notifier block
@@ -802,7 +975,9 @@ static int vfio_ap_mdev_iommu_notifier(struct notifier_block *nb,
 		struct vfio_iommu_type1_dma_unmap *unmap = data;
 		unsigned long g_pfn = unmap->iova >> PAGE_SHIFT;
 
-		vfio_unpin_pages(mdev_dev(matrix_mdev->mdev), &g_pfn, 1);
+		if (matrix_mdev->mdev)
+			vfio_unpin_pages(mdev_dev(matrix_mdev->mdev),
+					 &g_pfn, 1);
 		return NOTIFY_OK;
 	}
 
@@ -877,11 +1052,15 @@ static int vfio_ap_mdev_reset_queue(unsigned int apid, unsigned int apqi,
 				    unsigned int retry)
 {
 	struct ap_queue_status status;
+	struct vfio_ap_queue *q;
+
+	q = vfio_ap_get_queue(AP_MKQID(apid, apqi));
 
 	do {
 		status = ap_zapq(AP_MKQID(apid, apqi));
 		switch (status.response_code) {
 		case AP_RESPONSE_NORMAL:
+			vfio_ap_free_irq(q);
 			return 0;
 		case AP_RESPONSE_RESET_IN_PROGRESS:
 		case AP_RESPONSE_BUSY:
@@ -999,6 +1178,11 @@ static int vfio_ap_mdev_open(struct mdev_device *mdev)
 	if (ret)
 		goto err_group;
 
+	if (!matrix_mdev->kvm) {
+		ret = -ENODEV;
+		goto err_iommu;
+	}
+
 	matrix_mdev->iommu_notifier.notifier_call = vfio_ap_mdev_iommu_notifier;
 	events = VFIO_IOMMU_NOTIFY_DMA_UNMAP;
 
@@ -1011,6 +1195,7 @@ static int vfio_ap_mdev_open(struct mdev_device *mdev)
 	if (ret)
 		goto err_associate;
 
+	matrix_mdev->kvm->arch.crypto.pqap_hook = handle_pqap;
 	return 0;
 
 err_associate:
@@ -1031,12 +1216,12 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev)
 	if (matrix_mdev->kvm)
 		kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
 
-	vfio_ap_mdev_reset_queues(mdev);
+	matrix_mdev->kvm->arch.crypto.pqap_hook = NULL;
+	vfio_ap_dissociate_queues(matrix_mdev);
 	vfio_unregister_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY,
 				 &matrix_mdev->group_notifier);
 	vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
 				 &matrix_mdev->iommu_notifier);
-	vfio_ap_dissociate_queues(matrix_mdev);
 	matrix_mdev->kvm = NULL;
 	module_put(THIS_MODULE);
 }
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 2781720..16c99e9 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -92,5 +92,7 @@ struct vfio_ap_queue {
 	struct device *dev;
 	int	apqn;
 	struct ap_matrix_mdev *matrix;
+	unsigned long nib;
+	unsigned char isc;
 };
 #endif /* _VFIO_AP_PRIVATE_H_ */
-- 
2.7.4

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