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SubjectRe: [PATCH v3 07/14] KVM: s390: interfaces to configure/deconfigure guest's AP matrix
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On 04/03/2018 07:07 AM, Cornelia Huck wrote:
> On Wed, 14 Mar 2018 14:25:47 -0400
> Tony Krowiak <akrowiak@linux.vnet.ibm.com> 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.
>>
>> This patch will set the bits in the APM, AQM and ADM fields of the
>> CRYCB referenced by the KVM guest's SIE state description. The process
>> used is:
>>
>> 1. Verify that the bits to be set do not exceed the maximum bit
>> number for the given mask.
>>
>> 2. Verify that the APQNs that can be derived from the intersection
>> of the bits set in the APM and AQM fields of the KVM guest's CRYCB
>> are not assigned to any other KVM guest running on the same linux
>> host.
>>
>> 3. Set the APM, AQM and ADM in the CRYCB according to the matrix
>> configured for the mediated matrix device via its sysfs
>> adapter, domain and control domain attribute files respectively.
>>
>> Signed-off-by: Tony Krowiak <akrowiak@linux.vnet.ibm.com>
>> ---
>> arch/s390/include/asm/kvm-ap.h | 36 +++++
>> arch/s390/kvm/kvm-ap.c | 268 +++++++++++++++++++++++++++++++++
>> drivers/s390/crypto/vfio_ap_ops.c | 19 +++
>> drivers/s390/crypto/vfio_ap_private.h | 4 +
>> 4 files changed, 327 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/s390/kvm/kvm-ap.c b/arch/s390/kvm/kvm-ap.c
>> index a2c6ad2..eb365e2 100644
>> --- a/arch/s390/kvm/kvm-ap.c
>> +++ b/arch/s390/kvm/kvm-ap.c
>> @@ -8,9 +8,129 @@
>>
>> #include <asm/kvm-ap.h>
>> #include <asm/ap.h>
>> +#include <linux/bitops.h>
>>
>> #include "kvm-s390.h"
>>
>> +static inline void kvm_ap_clear_crycb_masks(struct kvm *kvm)
>> +{
>> + int crycb_fmt = kvm->arch.crypto.crycbd & CRYCB_FORMAT_MASK;
>> +
>> + if (crycb_fmt == CRYCB_FORMAT2)
>> + memset(&kvm->arch.crypto.crycb->apcb1, 0,
>> + sizeof(kvm->arch.crypto.crycb->apcb1));
>> + else
>> + memset(&kvm->arch.crypto.crycb->apcb0, 0,
>> + sizeof(kvm->arch.crypto.crycb->apcb0));
>> +}
> Should that rather be a switch/case? If there's a CRYCB_FORMAT3 in the
> future, I'd think that it's more likely that it uses apcb1 and not
> apcb0. Can't comment further without the architecture, obviously.
Maybe we should just clear both structures without regard to the CRYCB
format.
>
> (...)
>
>> +static void kvm_ap_set_crycb_masks(struct kvm *kvm,
>> + struct kvm_ap_matrix *matrix)
>> +{
>> + unsigned long *apm = kvm_ap_get_crycb_apm(kvm);
>> + unsigned long *aqm = kvm_ap_get_crycb_aqm(kvm);
>> + unsigned long *adm = kvm_ap_get_crycb_adm(kvm);
>> +
>> + kvm_ap_clear_crycb_masks(kvm);
>> + memcpy(apm, matrix->apm, KVM_AP_MASK_BYTES(matrix->apm_max));
>> + memcpy(aqm, matrix->aqm, KVM_AP_MASK_BYTES(matrix->aqm_max));
>> +
>> + /*
>> + * Merge the AQM and ADM since the ADM is a superset of the
>> + * AQM by architectural convention.
> Is this 'architectural convention' in the sense of 'there's a statement
> in the architecture that it always is like that', or in the sense of
> 'all real-life systems are like that'?
> [From my sketchy memory, this convention makes sense but is not
> enshrined; but I might misremember.]
The documentation states it is an agreed upon convention.
>
>> + */
>> + bitmap_or(adm, adm, aqm, matrix->adm_max);
>> +}


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