From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cornelia Huck Subject: Re: [PATCH v4 1/7] s390: ap: kvm: add PQAP interception for AQIC Date: Thu, 28 Feb 2019 14:52:54 +0100 Message-ID: <20190228145254.2909425e.cohuck@redhat.com> References: <1550849400-27152-1-git-send-email-pmorel@linux.ibm.com> <1550849400-27152-2-git-send-email-pmorel@linux.ibm.com> <9f1d9241-39b9-adbc-d0e9-cb702e609cbc@linux.ibm.com> <4dc59125-7f96-cba8-651b-382ed8f8bff8@linux.ibm.com> <8526f468-9a4d-68d2-3868-0dad5ce16f46@linux.ibm.com> <6058a017-6404-af3c-62ef-2452214ac97c@de.ibm.com> <2391adc2-6611-034c-61c5-feb46e2a751b@de.ibm.com> <20190228122251.75b31f62.cohuck@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Christian Borntraeger , Tony Krowiak , 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: Pierre Morel Return-path: In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On Thu, 28 Feb 2019 14:16:09 +0100 Pierre Morel wrote: > On 28/02/2019 12:22, Cornelia Huck wrote: > > So, to summarize, the function should do: > > - Is userspace supposed to emulate everything (!ECA_APIE)? Return > > -EOPNOTSUPP to hand control to it. > > - We are now interpreting the instruction in KVM. Do common checks > > (PSTATE etc.) and inject exceptions, if needed. > > - Now look at the fc; if there's a handler for it, call that; if not > > (case does not attempt to call a specific handler, or no handler > > registered), inject a specification exception. (Do we want pre-checks > > like for facility 65 here, or in the handler?) > > > > That response code 0x01 thingy probably needs to go into the specific > > handler function, if anywhere (don't know the semantics, sorry). > > What do you mean with specific handler function? > > If you mean a switch around the FC with static function's call, I agree, > if you mean a jump into a hook I do not agree. Ah, ok; so each case (that we want to handle) should call into a subhandler that does { (... check things like facilities ...) if (!specific_hook) inject_specif_excp_and_return(); ret = specific_hook(); if (ret) set_resp_code_0x01(); // or in specific_hook()? } ? > > > > Question: Will the handlers for the individual fcs need to generate > > different exceptions on their own? I.e., do they need to do injections > > themselves, or should the calling function possibly inject an exception > > on error? > > There are some specificities. Ok, should probably done in the subhandlers? (I hope I don't muddy the waters too much; but basically, I'm poking around with a stick in the dark :)