From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Krowiak Subject: Re: [PATCH v3 2/9] s390: ap: kvm: setting a hook for PQAP instructions Date: Tue, 19 Feb 2019 17:50:56 -0500 Message-ID: <342ffd56-b73a-b1f4-004d-de2c4aeef729@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> <74d812c6-bf83-0fb0-8fc3-af1341b0ae3c@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <74d812c6-bf83-0fb0-8fc3-af1341b0ae3c@linux.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: pmorel@linux.ibm.com, Cornelia Huck Cc: 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 List-ID: 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 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 think I understand where you are coming from. In looking back at the original patch, I see there are checks using the test_kvm_facility and kvm_s390_inject_program_int functions placed after your check for fc != 0x03. You clearly misunderstood what I was asking you to do. I was suggesting that ONLY the check for 'fc != 0x03' be done in the hook. I was NOT suggesting the instructions following the check for fc != 0x03 be done in the hook, so there is no need to export any KVM functions. > >> 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 > >