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    SubjectRe: [PATCH v9 3/4] s390: ap: implement PAPQ AQIC interception in kernel
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    Date
    On 21.05.19 17:34, Pierre Morel wrote:
    > We register a AP PQAP instruction hook during the open
    > of the mediated device. And unregister it on release.
    >
    > During the probe of the AP device, we allocate a vfio_ap_queue
    > structure to keep track of the information we need for the
    > PQAP/AQIC instruction interception.
    >
    > 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 retrieve the mediated device to use the VFIO pinning
    > infrastructure 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
    > - unpin the NIB
    >
    > When removing the AP device from the driver the device is
    > reseted and this process unregisters the GISA from the GIB,
    > and unpins the NIB address then we free the vfio_ap_queue
    > structure.
    >
    > Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
    > ---
    > drivers/s390/crypto/vfio_ap_drv.c | 34 +++-
    > drivers/s390/crypto/vfio_ap_ops.c | 336 +++++++++++++++++++++++++++++++++-
    > drivers/s390/crypto/vfio_ap_private.h | 11 ++
    > 3 files changed, 374 insertions(+), 7 deletions(-)
    >
    > diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
    > index e9824c3..003662a 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@linux.ibm.com>
    > + * Pierre Morel <pmorel@linux.ibm.com>
    > */
    >
    > #include <linux/module.h>
    > @@ -40,14 +41,45 @@ 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->saved_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;
    > + int apid, apqi;
    > +
    > + mutex_lock(&matrix_dev->lock);
    > + q = dev_get_drvdata(&apdev->device);
    > + 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);
    > }
    >
    > 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..015174f 100644
    > --- a/drivers/s390/crypto/vfio_ap_ops.c
    > +++ b/drivers/s390/crypto/vfio_ap_ops.c
    > @@ -24,6 +24,295 @@
    > #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_wait_for_irqclear
    > + * @apqn: The AP Queue number
    > + *
    > + * Checks the IRQ bit for the status of this APQN using ap_tapq.
    > + * Returns if the ap_tapq function succedded and the bit is clear.
    > + * Returns if ap_tapq function failed with invalid, deconfigured or
    > + * checkstopped AP.
    > + * Otherwise retries up to 5 times after waiting 20ms.
    > + *
    > + */
    > +static void vfio_ap_wait_for_irqclear(int apqn)
    > +{
    > + struct ap_queue_status status;
    > + int retry = 5;
    > +
    > + do {
    > + status = ap_tapq(apqn, NULL);
    > + switch (status.response_code) {
    > + case AP_RESPONSE_NORMAL:
    > + case AP_RESPONSE_RESET_IN_PROGRESS:
    > + if (!status.irq_enabled)
    > + return;
    > + /* Fall through */
    > + case AP_RESPONSE_BUSY:
    > + msleep(20);
    > + break;
    > + case AP_RESPONSE_Q_NOT_AVAIL:
    > + case AP_RESPONSE_DECONFIGURED:
    > + case AP_RESPONSE_CHECKSTOPPED:
    > + default:
    > + WARN_ONCE(1, "%s: tapq rc %02x: %04x\n", __func__,
    > + status.response_code, apqn);
    > + return;
    > + }
    > + } while (--retry);
    > +
    > + WARN_ONCE(1, "%s: tapq rc %02x: %04x could not clear IR bit\n",
    > + __func__, status.response_code, apqn);
    > +}
    > +
    > +/**
    > + * vfio_ap_free_aqic_resources
    > + * @q: The vfio_ap_queue
    > + *
    > + * Unregisters the ISC in the GIB when the saved ISC not invalid.
    > + * Unpin the guest's page holding the NIB when it exist.
    > + * Reset the saved_pfn and saved_isc to invalid values.
    > + * Clear the pointer to the matrix mediated device.
    > + *
    > + */
    > +static void vfio_ap_free_aqic_resources(struct vfio_ap_queue *q)
    > +{
    > + if (q->saved_isc != VFIO_AP_ISC_INVALID && q->matrix_mdev)
    > + kvm_s390_gisc_unregister(q->matrix_mdev->kvm, q->saved_isc);
    > + if (q->saved_pfn && 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->matrix_mdev = NULL;
    > +}
    > +
    > +/**
    > + * vfio_ap_irq_disable
    > + * @q: The vfio_ap_queue
    > + *
    > + * Uses ap_aqic to disable the interruption and in case of success, reset
    > + * in progress or IRQ disable command already proceeded: calls
    > + * vfio_ap_wait_for_irqclear() to check for the IRQ bit to be clear
    > + * and calls vfio_ap_free_aqic_resources() to free the resources associated
    > + * with the AP interrupt handling.
    > + *
    > + * In the case the AP is busy, or a reset is in progress,
    > + * retries after 20ms, up to 5 times.
    > + *
    > + * 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)
    > +{
    > + struct ap_qirq_ctrl aqic_gisa = {};
    > + struct ap_queue_status status;
    > + int retries = 5;
    > +
    > + do {
    > + status = ap_aqic(q->apqn, aqic_gisa, NULL);
    > + switch (status.response_code) {
    > + case AP_RESPONSE_OTHERWISE_CHANGED:
    > + case AP_RESPONSE_NORMAL:
    > + vfio_ap_wait_for_irqclear(q->apqn);
    > + goto end_free;
    > + case AP_RESPONSE_RESET_IN_PROGRESS:
    > + case AP_RESPONSE_BUSY:
    > + msleep(20);
    > + break;
    > + case AP_RESPONSE_Q_NOT_AVAIL:
    > + case AP_RESPONSE_DECONFIGURED:
    > + case AP_RESPONSE_CHECKSTOPPED:
    > + case AP_RESPONSE_INVALID_ADDRESS:
    > + default:
    > + /* All cases in default means AP not operational */
    > + WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
    > + status.response_code);
    > + goto end_free;
    > + }
    > + } while (retries--);
    > +
    > + WARN_ONCE(1, "%s: ap_aqic status %d\n", __func__,
    > + status.response_code);
    > +end_free:
    > + vfio_ap_free_aqic_resources(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 AP_RESPONSE_INVALID_ADDRESS in case the
    > + * vfio_pin_pages failed.
    > + *
    > + * Otherwise return the ap_queue_status returned by the ap_aqic(),
    > + * all retry handling will be done by the guest.
    > + */
    > +static struct ap_queue_status vfio_ap_irq_enable(struct vfio_ap_queue *q,
    > + int isc,
    > + unsigned long nib)
    > +{
    > + struct ap_qirq_ctrl aqic_gisa = {};
    > + struct ap_queue_status status = {};
    > + struct kvm_s390_gisa *gisa;
    > + struct kvm *kvm;
    > + unsigned long h_nib, g_pfn, h_pfn;
    > + int ret;
    > +
    > + g_pfn = 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;
    > + default:
    > + status.response_code = AP_RESPONSE_INVALID_ADDRESS;
    > + return status;
    > + }
    > +
    > + kvm = q->matrix_mdev->kvm;
    > + gisa = kvm->arch.gisa_int.origin;
    > +
    > + h_nib = (h_pfn << PAGE_SHIFT) | (nib & ~PAGE_MASK);
    > + aqic_gisa.gisc = isc;
    > + aqic_gisa.isc = kvm_s390_gisc_register(kvm, isc);
    > + aqic_gisa.ir = 1;
    > + aqic_gisa.gisa = (uint64_t)gisa >> 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 */
    > + vfio_ap_free_aqic_resources(q);
    > + q->saved_pfn = g_pfn;
    > + q->saved_isc = 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), &g_pfn, 1);
    > + kvm_s390_gisc_unregister(kvm, isc);
    > + break;
    > + default:
    > + pr_warn("%s: apqn %04x: response: %02x\n", __func__, q->apqn,
    > + status.response_code);
    > + vfio_ap_irq_disable(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)
    > + qstatus = vfio_ap_irq_enable(q, status & 0x07,
    > + vcpu->run->s.regs.gprs[2]);
    > + else
    > + qstatus = vfio_ap_irq_disable(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 +334,11 @@ 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 +354,7 @@ 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 +1047,8 @@ 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 +1114,36 @@ 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)
    > +static void vfio_ap_irq_disable_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_irq_disable(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);
    > return 0;
    > case AP_RESPONSE_RESET_IN_PROGRESS:
    > case AP_RESPONSE_BUSY:
    > @@ -861,6 +1177,7 @@ static int vfio_ap_mdev_reset_queues(struct mdev_device *mdev)
    > */
    > if (ret)
    > rc = ret;
    > + vfio_ap_irq_disable_apqn(AP_MKQID(apid, apqi));
    > }
    > }
    >
    > @@ -904,15 +1221,20 @@ 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 +1263,7 @@ 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 +1275,7 @@ 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..f46dde5 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@linux.ibm.com>
    > * Halil Pasic <pasic@linux.ibm.com>
    > + * Pierre Morel <pmorel@linux.ibm.com>
    > *
    > * Copyright IBM Corp. 2018
    > */
    > @@ -89,5 +90,15 @@ struct ap_matrix_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;
    > + int apqn;
    > +#define VFIO_AP_ISC_INVALID 0xff
    > + unsigned char saved_isc;
    > +};
    > +struct ap_queue_status vfio_ap_irq_disable(struct vfio_ap_queue *q);
    > #endif /* _VFIO_AP_PRIVATE_H_ */
    acked-by: Harald Freudenberger <freude@linux.ibm.com>

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