Messages in this thread | | | Subject | Re: [PATCH v3 2/9] s390: ap: kvm: setting a hook for PQAP instructions | From | Pierre Morel <> | Date | Thu, 21 Feb 2019 13:40:33 +0100 |
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On 19/02/2019 23:36, Tony Krowiak wrote: > On 2/19/19 2:50 PM, Pierre Morel wrote: >> On 18/02/2019 23:42, Cornelia Huck wrote: >>> On Mon, 18 Feb 2019 19:29:10 +0100 >>> Pierre Morel <pmorel@linux.ibm.com> wrote: >>> >>>> On 15/02/2019 23:02, Tony Krowiak wrote: >>>>> On 2/14/19 8:51 AM, Pierre Morel wrote: >>> >>>>>> +/* >>>>>> + * handle_pqap: Handling pqap interception >>>>>> + * @vcpu: the vcpu having issue the pqap instruction >>>>>> + * >>>>>> + * This callback only handles PQAP/AQIC instruction and >>>>>> + * 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. >>>>>> + * - 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; >>>>> >>>>> This does not belong here. Function code 3 is one of 7 function codes >>>>> that can be sent with the PQAP instruction. This belongs in the PQAP >>>>> hook code. >>>> >>>> On one hand, effectively I would prefer to put the code in the VFIO >>>> driver code. >>>> On the other hand, doing this would lead to export the code for >>>> test_kvm_facility() and kvm_s390_inject_program_int() from the >>>> kvm-s390.h >>>> >>>> I choose not to export these functions from the KVM code. >>>> >>>> Would like opinion from KVM maintainers? >>> >>> Looking at this (and without access to the specification...), I think >>> the check for problem state makes sense in here (if this applies to all >>> PQAP functions equally, which seems likely). The check for the facility >>> makes more sense in the handler. You can probably still inject the >>> specification exception here if you use a clever return code. >>> >> >> If there is no objection on exporting the KVM functions... I can do this. > > I do not understand why you would have to export KVM functions to place > the check for FC 0x03 in the pqap hook? What am I missing here? Maybe > you misunderstood my comment?
No I did not but in between I discovered an error in the handling of the interception of PQAP/AQIC.
QEMU and KVM can both accept PQAP/AQIC even if the vfio_ap driver is not loaded. However now that the guest officially get the PQAP/AQIC instruction we need to handle the specification and operation exceptions inside KVM _before_ testing and even calling the driver hook.
I will make the changes in the next iteration.
Regards, Pierre
-- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany
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