Re: [PATCH v3 2/9] s390: ap: kvm: setting a hook for PQAP instructions

Pierre Morel
2019-02-14T16:45:06Z

On 14/02/2019 16:54, Cornelia Huck wrote:
> On Thu, 14 Feb 2019 14:51:02 +0100
> Pierre Morel <pmorel@linux.ibm.com> wrote:
>
>> This patch adds interception code for the PQAP instructions,
>> and a callback inside the KVM arch structure for s390.
>>
>> If a VFIO-AP drivers needs to intercept PQAP/AQIC or PQAP/TAPQ
>
> s/drivers/driver/

thanks. OK

>

...

>> #include "kvm-s390.h"
>> #include "trace.h"
>> @@ -592,6 +593,53 @@ static int handle_io_inst(struct kvm_vcpu *vcpu)
>> }
>> }
>>
>> +/*
>> + * handle_pqap: Handling pqap interception
>> + * @vcpu: the vcpu having issue the pqap instruction
>
> s/issue/issued/

OK. thanks.

>
>> + *
>> + * This callback only handles PQAP/AQIC instruction and
>
> Here you only talk about PQAP/AQIC, what about PQAP/TAPQ mentioned in
> the patch description?

I can add "for now" or "in this patch" or suppress the reference to
PAPQ/TAPQ

>
>> + * calls a dedicated callback for this instruction if
>> + * a driver did register one in the CRYPTO satellite of the
>> + * SIE block.
>> + *
>> + * Do not change the behavior if, return -EOPNOTSUPP if:
>> + * - the hook is not used do not change the behavior.
>
> The hook is not used? Or not set?

I think "is not set" is better.

> (I don't think you need to repeat "do
> not change the behavior".)

OK

>
>> + * - AP instructions are not available or not available to the guest
>> + * - the instruction is not PQAP with function code indicating
>> + * AQIC do not change the previous behavior.
>> + *
>> + * For PQAP/AQIC instruction, verify privilege and specifications
>> + *
>> + * return the value returned by the callback.
>> + */
>> +static int handle_pqap(struct kvm_vcpu *vcpu)
>> +{
>> + uint8_t fc;
>> +
>> + /* Verify that the hook callback is registered */
>> + if (!vcpu->kvm->arch.crypto.pqap_hook)
>> + return -EOPNOTSUPP;
>> + /* Verify that the AP instruction are available */
>> + if (!ap_instructions_available())
>> + return -EOPNOTSUPP;
>> + /* Verify that the guest is allowed to use AP instructions */
>> + if (!(vcpu->arch.sie_block->eca & ECA_APIE))
>> + return -EOPNOTSUPP;
>> + /* Verify that the function code is AQIC */
>> + fc = vcpu->run->s.regs.gprs[0] >> 24;
>> + if (fc != 0x03)
>> + return -EOPNOTSUPP;
>> +
>> + /* PQAP instructions are allowed for guest kernel only */
>> + if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
>> + return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
>> + /* AQIC instruction is allowed only if facility 65 is available */
>> + if (!test_kvm_facility(vcpu->kvm, 65))
>> + return kvm_s390_inject_program_int(vcpu, PGM_SPECIFICATION);
>> + /* All right, call the callback */
>> + return vcpu->kvm->arch.crypto.pqap_hook(vcpu);
>
> Can that callback also return -EOPNOTSUPP to order to drop to user
> space?

Yes.
Why not?

>
>> +}
>> +
>> static int handle_stfl(struct kvm_vcpu *vcpu)
>> {
>> int rc;
>> @@ -878,6 +926,8 @@ int kvm_s390_handle_b2(struct kvm_vcpu *vcpu)
>> return handle_sthyi(vcpu);
>> case 0x7d:
>> return handle_stsi(vcpu);
>> + case 0xaf:
>> + return handle_pqap(vcpu);
>> case 0xb1:
>> return handle_stfl(vcpu);
>> case 0xb2:
>

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