linux-kernel - Re: [PATCH v11 06/14] s390/vfio-ap: introduce shadow APCB

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Date:   Fri, 13 Nov 2020 12:18:02 -0500
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     Halil Pasic <pasic@...ux.ibm.com>
Cc:     linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, freude@...ux.ibm.com, borntraeger@...ibm.com,
        cohuck@...hat.com, mjrosato@...ux.ibm.com,
        alex.williamson@...hat.com, kwankhede@...dia.com,
        fiuczy@...ux.ibm.com, frankja@...ux.ibm.com, david@...hat.com,
        hca@...ux.ibm.com, gor@...ux.ibm.com
Subject: Re: [PATCH v11 06/14] s390/vfio-ap: introduce shadow APCB



On 10/28/20 4:11 AM, Halil Pasic wrote:
> On Thu, 22 Oct 2020 13:12:01 -0400
> Tony Krowiak <akrowiak@...ux.ibm.com> wrote:
>
>> The APCB is a field within the CRYCB that provides the AP configuration
>> to a KVM guest. Let's introduce a shadow copy of the KVM guest's APCB and
>> maintain it for the lifespan of the guest.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@...ux.ibm.com>
>> ---
>>   drivers/s390/crypto/vfio_ap_ops.c     | 24 +++++++++++++++++++-----
>>   drivers/s390/crypto/vfio_ap_private.h |  2 ++
>>   2 files changed, 21 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
>> index 9e9fad560859..9791761aa7fd 100644
>> --- a/drivers/s390/crypto/vfio_ap_ops.c
>> +++ b/drivers/s390/crypto/vfio_ap_ops.c
>> @@ -320,6 +320,19 @@ static void vfio_ap_matrix_init(struct ap_config_info *info,
>>   	matrix->adm_max = info->apxa ? info->Nd : 15;
>>   }
>>   
>> +static bool vfio_ap_mdev_has_crycb(struct ap_matrix_mdev *matrix_mdev)
>> +{
>> +	return (matrix_mdev->kvm && matrix_mdev->kvm->arch.crypto.crycbd);
>> +}
>> +
>> +static void vfio_ap_mdev_commit_shadow_apcb(struct ap_matrix_mdev *matrix_mdev)
>> +{
>> +	kvm_arch_crypto_set_masks(matrix_mdev->kvm,
>> +				  matrix_mdev->shadow_apcb.apm,
>> +				  matrix_mdev->shadow_apcb.aqm,
>> +				  matrix_mdev->shadow_apcb.adm);
>> +}
>> +
>>   static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>>   {
>>   	struct ap_matrix_mdev *matrix_mdev;
>> @@ -335,6 +348,7 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
>>   
>>   	matrix_mdev->mdev = mdev;
>>   	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
>> +	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
>>   	hash_init(matrix_mdev->qtable);
>>   	mdev_set_drvdata(mdev, matrix_mdev);
>>   	matrix_mdev->pqap_hook.hook = handle_pqap;
>> @@ -1213,13 +1227,12 @@ static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
>>   	if (ret)
>>   		return NOTIFY_DONE;
>>   
>> -	/* If there is no CRYCB pointer, then we can't copy the masks */
>> -	if (!matrix_mdev->kvm->arch.crypto.crycbd)
>> +	if (!vfio_ap_mdev_has_crycb(matrix_mdev))
>>   		return NOTIFY_DONE;
>>   
>> -	kvm_arch_crypto_set_masks(matrix_mdev->kvm, matrix_mdev->matrix.apm,
>> -				  matrix_mdev->matrix.aqm,
>> -				  matrix_mdev->matrix.adm);
>> +	memcpy(&matrix_mdev->shadow_apcb, &matrix_mdev->matrix,
>> +	       sizeof(matrix_mdev->shadow_apcb));
>> +	vfio_ap_mdev_commit_shadow_apcb(matrix_mdev);
>>   
>>   	return NOTIFY_OK;
>>   }
>> @@ -1329,6 +1342,7 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev)
>>   		kvm_put_kvm(matrix_mdev->kvm);
>>   		matrix_mdev->kvm = NULL;
>>   	}
>> +
> Unrelated change.
>
> Otherwise patch looks OK.
>
> Reviewed-by: Halil Pasic <pasic@...ux.ibm.com>

I'll fix it. Thanks for your review.

>
>>   	mutex_unlock(&matrix_dev->lock);
>>   
>>   	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 c1d8b5507610..fc8634cee485 100644
>> --- a/drivers/s390/crypto/vfio_ap_private.h
>> +++ b/drivers/s390/crypto/vfio_ap_private.h
>> @@ -75,6 +75,7 @@ struct ap_matrix {
>>    * @list:	allows the ap_matrix_mdev struct to be added to a list
>>    * @matrix:	the adapters, usage domains and control domains assigned to the
>>    *		mediated matrix device.
>> + * @shadow_apcb:    the shadow copy of the APCB field of the KVM guest's CRYCB
>>    * @group_notifier: notifier block used for specifying callback function for
>>    *		    handling the VFIO_GROUP_NOTIFY_SET_KVM event
>>    * @kvm:	the struct holding guest's state
>> @@ -82,6 +83,7 @@ struct ap_matrix {
>>   struct ap_matrix_mdev {
>>   	struct list_head node;
>>   	struct ap_matrix matrix;
>> +	struct ap_matrix shadow_apcb;
>>   	struct notifier_block group_notifier;
>>   	struct notifier_block iommu_notifier;
>>   	struct kvm *kvm;