[PATCH v3 7/9] s390: ap: implement PAPQ AQIC interception in kernel

Pierre Morel
2019-02-14T13:51:39Z

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@linux.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