linux-kernel - Re: [PATCH v2 07/15] KVM: s390: Interfaces to configure/deconfigure guest's AP matrix

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Date:   Wed, 28 Feb 2018 17:15:45 +0100
From:   Pierre Morel <pmorel@...ux.vnet.ibm.com>
To:     Tony Krowiak <akrowiak@...ux.vnet.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org
Cc:     freude@...ibm.com, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, borntraeger@...ibm.com,
        cohuck@...hat.com, kwankhede@...dia.com,
        bjsdjshi@...ux.vnet.ibm.com, pbonzini@...hat.com,
        alex.williamson@...hat.com, alifm@...ux.vnet.ibm.com,
        mjrosato@...ux.vnet.ibm.com, jjherne@...ux.vnet.ibm.com,
        thuth@...hat.com, pasic@...ux.vnet.ibm.com,
        fiuczy@...ux.vnet.ibm.com, buendgen@...ibm.com
Subject: Re: [PATCH v2 07/15] KVM: s390: Interfaces to configure/deconfigure
 guest's AP matrix

On 27/02/2018 15:28, Tony Krowiak wrote:
> Provides interfaces to assign AP adapters, usage domains
> and control domains to a KVM guest.
>
> A KVM guest is started by executing the Start Interpretive Execution (SIE)
> instruction. The SIE state description is a control block that contains the
> state information for a KVM guest and is supplied as input to the SIE
> instruction. The SIE state description has a satellite structure called the
> Crypto Control Block (CRYCB). The CRYCB contains three bitmask fields
> identifying the adapters, queues (domains) and control domains assigned to
> the KVM guest:
>
> * The AP Adapter Mask (APM) field identifies the AP adapters assigned to
>    the KVM guest
>
> * The AP Queue Mask (AQM) field identifies the AP queues assigned to
>    the KVM guest. Each AP queue is connected to a usage domain within
>    an AP adapter.
>
> * The AP Domain Mask (ADM) field identifies the control domains
>    assigned to the KVM guest.
>
> Each adapter, queue (usage domain) and control domain are identified by
> a number from 0 to 255. The bits in each mask, from most significant to
> least significant bit, correspond to the numbers 0-255. When a bit is
> set, the corresponding adapter, queue (usage domain) or control domain
> is assigned to the KVM guest.

...snip...

>   static int kvm_ap_apxa_installed(void)
>   {
>   	int ret;
> @@ -50,3 +170,140 @@ void kvm_ap_set_crycb_format(struct kvm *kvm, __u32 *crycbd)
>   			*crycbd |= CRYCB_FORMAT1;
>   	}
>   }
> +
> +static int kvm_ap_matrix_apm_create(struct kvm_ap_matrix *ap_matrix, int apxa)
> +{
> +	if (apxa)
> +		ap_matrix->apm_max = 256;

AFAIK the number of possible bits in the masks for a system is not a 
generic value but is
returned by the QCI instruction.
Is there a reason to use a fix value?

> +	else
> +		ap_matrix->apm_max = 64;
> +
> +	ap_matrix->apm = kzalloc(KVM_AP_MASK_BYTES(ap_matrix->apm_max),
> +				 GFP_KERNEL);
> +	if (!ap_matrix->apm)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static int kvm_ap_matrix_aqm_create(struct kvm_ap_matrix *ap_matrix, int apxa)
> +{
> +	if (apxa)
> +		ap_matrix->aqm_max = 256;

same here

> +	else
> +		ap_matrix->aqm_max = 16;
> +
> +	ap_matrix->aqm = kzalloc(KVM_AP_MASK_BYTES(ap_matrix->aqm_max),
> +				 GFP_KERNEL);
> +	if (!ap_matrix->aqm)
> +		return -ENOMEM;
> +
> +	return 0;
> +}
> +
> +static int kvm_ap_matrix_adm_create(struct kvm_ap_matrix *ap_matrix, int apxa)
> +{
> +	if (apxa)
> +		ap_matrix->adm_max = 256;

and here


Pierre

-- 
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany