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Date: Tue, 19 Feb 2019 20:16:34 +0100
From: Pierre Morel <pmorel@...ux.ibm.com>
To: Tony Krowiak <akrowiak@...ux.ibm.com>, 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, pasic@...ux.ibm.com,
david@...hat.com, schwidefsky@...ibm.com,
heiko.carstens@...ibm.com, freude@...ux.ibm.com, mimu@...ux.ibm.com
Subject: Re: [PATCH v3 7/9] s390: ap: implement PAPQ AQIC interception in
kernel
On 16/02/2019 00:11, Tony Krowiak wrote:
> On 2/14/19 8:51 AM, Pierre Morel wrote:
>> 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.
>> + */
>
> This function be nothing more than a switch statement for the
> function code sent with the PQAP instruction. Each case should
> be a call to a appropriate PQAP function handler. This will make
> it much easier to add additional handlers for the 6 other
> PQAP functions if necessary at some time down the road.
AFAIK there are only two PQAP functions we can intercept.
I will give attention to this function.
I will wait to this on the answers from KVM maintainers to know which
KVM functions I can use here.
>
>> +static int handle_pqap(struct kvm_vcpu *vcpu)
>> +{ int ret.
> uint8_t fc;
>
> fc = vcpu->run->s.regs.gprs[0] >> 24;
> switch(fc) {
> case 0x03:
> ret = handle_pqap_aqic(vcpu);
> default:
> ret = -EOPNOTSUPP;
> }
>
> return ret;
> }
>
> static int handle_pqap_aqic(struct kvm_vcpu *vcpu) {
>> + uint64_t status;
>> + uint16_t apqn;
> struct device *qdev;
>> + 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);
>
> Replace with:
> qdev = vfio_ap_get_queue_dev(apqn);
You asked to revisit the life cycle of the vfio_ap_queues in another thread.
I will do it.
Thanks
Pierre
--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany
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