linux-kernel - Re: [PATCH v19 05/20] s390/vfio-ap: refresh guest's APCB by filtering AP resources assigned to mdev

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Date:   Mon, 16 May 2022 13:13:43 -0400
From:   Tony Krowiak <akrowiak@...ux.ibm.com>
To:     jjherne@...ux.ibm.com, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     freude@...ux.ibm.com, borntraeger@...ibm.com, cohuck@...hat.com,
        mjrosato@...ux.ibm.com, pasic@...ux.ibm.com,
        alex.williamson@...hat.com, kwankhede@...dia.com,
        fiuczy@...ux.ibm.com
Subject: Re: [PATCH v19 05/20] s390/vfio-ap: refresh guest's APCB by filtering
 AP resources assigned to mdev

On 5/16/22 12:36 PM, Jason J. Herne wrote:
> On 4/4/22 18:10, Tony Krowiak wrote:
>> |@@ -1306,8 +1392,6 @@ static int vfio_ap_mdev_set_kvm(struct 
>> ap_matrix_mdev *matrix_mdev, kvm_get_kvm(kvm); matrix_mdev->kvm = 
>> kvm; - memcpy(&matrix_mdev->shadow_apcb, &matrix_mdev->matrix, - 
>> sizeof(struct ap_matrix)); kvm_arch_crypto_set_masks(kvm, 
>> matrix_mdev->shadow_apcb.apm, matrix_mdev->shadow_apcb.aqm, 
>> matrix_mdev->shadow_apcb.adm);|
>
> This looks like an unrelated change. Does this snippet really belong 
> to this patch?

It's kind of hard to tell which snippet you are talking about without 
the patch context, but I assume you are referring to the removal of the 
memcpy statement in the vfio_ap_mdev_set_kvm() function in which case 
this snippet belongs with this patch.

This patch introduces a function that filters the contents of the 
matrix_mdev->matrix to ensure that the matrix_mdev->shadow_apcb contains 
only queues that are bound to the vfio_ap device driver. The filtering 
function is called whenever an adapter, domain or control domain is 
assigned or unassigned, so it is no longer necessary to copy the 
contents of matrix_mdev->matrix into matrix_mdev->shadow_apcb before 
setting the masks in the guest; that will have already been done by the 
filter function.