From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH v3 2/9] s390: ap: kvm: setting a hook for PQAP instructions Date: Tue, 19 Feb 2019 20:50:58 +0100 Message-ID: <74d812c6-bf83-0fb0-8fc3-af1341b0ae3c@linux.ibm.com> References: <1550152269-6317-1-git-send-email-pmorel@linux.ibm.com> <1550152269-6317-3-git-send-email-pmorel@linux.ibm.com> <4b21f059-1d37-f341-bac7-5b1fe0d06521@linux.ibm.com> <20190218234235.7d9f547c.cohuck@redhat.com> Reply-To: pmorel@linux.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: Tony Krowiak , borntraeger@de.ibm.com, alex.williamson@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, frankja@linux.ibm.com, pasic@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com To: Cornelia Huck Return-path: In-Reply-To: <20190218234235.7d9f547c.cohuck@redhat.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 18/02/2019 23:42, Cornelia Huck wrote: > On Mon, 18 Feb 2019 19:29:10 +0100 > Pierre Morel 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. > Another option: Provide a way to register a callback per function code; > this allows you to still do the check here and extend it later for > other function codes (which will probably be indicated by another > facility). I like this option even better. Regards, Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany