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Subject[PATCH v4 5/7] s390: ap: implement PAPQ AQIC interception in kernel
Date
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>
---
arch/s390/include/asm/kvm_host.h | 1 +
drivers/s390/crypto/ap_bus.h | 1 +
drivers/s390/crypto/vfio_ap_ops.c | 199 +++++++++++++++++++++++++++++++++-
drivers/s390/crypto/vfio_ap_private.h | 1 +
4 files changed, 199 insertions(+), 3 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 49cc8b0..5f3bb8c 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -720,6 +720,7 @@ struct kvm_s390_cpu_model {
struct kvm_s390_crypto {
struct kvm_s390_crypto_cb *crycb;
int (*pqap_hook)(struct kvm_vcpu *vcpu);
+ void *vfio_private;
__u32 crycbd;
__u8 aes_kw;
__u8 dea_kw;
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 1b5130a..0196065 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -43,7 +43,7 @@ struct vfio_ap_queue *vfio_ap_get_queue(int apqn, struct list_head *l)
return NULL;
}

-static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q)
+int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q)
{
struct ap_queue_status status;
int retry = 20;
@@ -75,6 +75,27 @@ static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q)
return -EBUSY;
}

+/**
+ * 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)
+{
+ if (!q)
+ return;
+ if (q->g_pfn)
+ vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev), &q->g_pfn, 1);
+ if (q->isc)
+ kvm_s390_gisc_unregister(q->matrix_mdev->kvm, q->isc);
+ q->nib = 0;
+ q->isc = 0;
+ q->g_pfn = 0;
+}
+
static void vfio_ap_matrix_init(struct ap_config_info *info,
struct ap_matrix *matrix)
{
@@ -97,6 +118,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
}

INIT_LIST_HEAD(&matrix_mdev->qlist);
+ 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);
@@ -109,10 +131,16 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
static int vfio_ap_mdev_remove(struct mdev_device *mdev)
{
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
+ struct vfio_ap_queue *q, *qtmp;

if (matrix_mdev->kvm)
return -EBUSY;

+ list_for_each_entry_safe(q, qtmp, &matrix_mdev->qlist, list) {
+ q->matrix_mdev = NULL;
+ vfio_ap_mdev_reset_queue(q);
+ list_move(&q->list, &matrix_dev->free_list);
+ }
mutex_lock(&matrix_dev->lock);
list_del(&matrix_mdev->node);
mutex_unlock(&matrix_dev->lock);
@@ -748,6 +776,161 @@ 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_mdev->kvm;
+ gisa = kvm->arch.gisa_int.origin;
+
+ g_pfn = q->nib >> PAGE_SHIFT;
+ ret = vfio_pin_pages(mdev_dev(q->matrix_mdev->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);
+ switch (status.response_code) {
+ case AP_RESPONSE_NORMAL:
+ if (q->g_pfn)
+ vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev),
+ &q->g_pfn, 1);
+ q->g_pfn = g_pfn;
+ break;
+ case AP_RESPONSE_OTHERWISE_CHANGED:
+ vfio_unpin_pages(mdev_dev(q->matrix_mdev->mdev), &g_pfn, 1);
+ break;
+ case AP_RESPONSE_INVALID_GISA:
+ status.response_code = AP_RESPONSE_INVALID_ADDRESS;
+ default: /* Fall Through */
+ pr_warn("%s: apqn %04x: response: %02x\n", __func__, q->apqn,
+ status.response_code);
+ vfio_ap_free_irq(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.
+ *
+ * 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;
+ matrix_mdev = vcpu->kvm->arch.crypto.vfio_private;
+ if (!matrix_mdev)
+ return -EOPNOTSUPP;
+ q = vfio_ap_get_queue(apqn, &matrix_mdev->qlist);
+ if (!q) {
+ qstatus.response_code = AP_RESPONSE_Q_NOT_AVAIL;
+ 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));
+ return 0;
+}
+
+ /*
* vfio_ap_mdev_iommu_notifier: IOMMU notifier callback
*
* @nb: The notifier block
@@ -767,9 +950,10 @@ static int vfio_ap_mdev_iommu_notifier(struct notifier_block *nb,

if (action == VFIO_IOMMU_NOTIFY_DMA_UNMAP) {
struct vfio_iommu_type1_dma_unmap *unmap = data;
- unsigned long g_pfn = unmap->iova >> PAGE_SHIFT;
+ unsigned long 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), &pfn, 1);
return NOTIFY_OK;
}

@@ -879,6 +1063,11 @@ 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;

@@ -887,6 +1076,8 @@ static int vfio_ap_mdev_open(struct mdev_device *mdev)
if (ret)
goto err_iommu;

+ matrix_mdev->kvm->arch.crypto.pqap_hook = handle_pqap;
+ matrix_mdev->kvm->arch.crypto.vfio_private = matrix_mdev;
return 0;

err_iommu:
@@ -905,6 +1096,8 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev)
kvm_arch_crypto_clear_masks(matrix_mdev->kvm);

vfio_ap_mdev_reset_queues(mdev);
+ matrix_mdev->kvm->arch.crypto.pqap_hook = NULL;
+ matrix_mdev->kvm->arch.crypto.vfio_private = NULL;
vfio_unregister_notifier(mdev_dev(mdev), VFIO_GROUP_NOTIFY,
&matrix_mdev->group_notifier);
vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY,
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index e535735..e2fd2c0 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -94,6 +94,7 @@ struct vfio_ap_queue {
struct list_head list;
struct ap_matrix_mdev *matrix_mdev;
unsigned long nib;
+ unsigned long g_pfn;
int apqn;
unsigned char isc;
};
--
2.7.4
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