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Thu, 18 Jul 2019 09:41:20 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [qemu-s390x] [PATCH for-4.1 1/2] s390x/pci: add some fallthrough annotations X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: David Hildenbrand , Stefan Weil , qemu-devel@nongnu.org, Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Wed, 17 Jul 2019 08:52:54 -0400 Collin Walling wrote: > On 7/17/19 5:27 AM, Christian Borntraeger wrote: > > > > > > On 17.07.19 10:54, Cornelia Huck wrote: > >> On Tue, 16 Jul 2019 14:34:22 -0400 > >> Collin Walling wrote: > >> > >>> On 7/16/19 11:20 AM, Cornelia Huck wrote: > >>>> On Wed, 10 Jul 2019 10:20:41 +0200 > >>>> Cornelia Huck wrote: > >>>> > >>>>> On Tue, 9 Jul 2019 18:55:34 -0400 > >>>>> Collin Walling wrote: > >>>>> > >>>>>> On 7/8/19 9:23 AM, Christian Borntraeger wrote: > >>>>>>> > >>>>>>> > >>>>>>> On 08.07.19 14:54, Cornelia Huck wrote: > >>>>>>>> According to the comment, the bits are supposed to accumulate. > >>>>>>>> > >>>>>>>> Reported-by: Stefan Weil > >>>>>>>> Fixes: 5d1abf234462 ("s390x/pci: enforce zPCI state checking") > >>>>>>>> Signed-off-by: Cornelia Huck > >>>>>>> > >>>>>>> This patch does not change behaviour, so it is certainly not wrong. > >>>>>>> > >>>>>>> So lets have a look at if the bug report was actually a real bug or > >>>>>>> just a missing annotation. > >>>>>>> > >>>>>>>> --- > >>>>>>>> hw/s390x/s390-pci-inst.c | 2 ++ > >>>>>>>> 1 file changed, 2 insertions(+) > >>>>>>>> > >>>>>>>> diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c > >>>>>>>> index 61f30b8e55d2..00235148bed7 100644 > >>>>>>>> --- a/hw/s390x/s390-pci-inst.c > >>>>>>>> +++ b/hw/s390x/s390-pci-inst.c > >>>>>>>> @@ -1209,8 +1209,10 @@ int stpcifc_service_call(S390CPU *cpu, uint8_t r1, uint64_t fiba, uint8_t ar, > >>>>>>>> * FH Enabled bit is set to one in states of ENABLED, BLOCKED or ERROR. */ > >>>>>>>> case ZPCI_FS_ERROR: > >>>>>>>> fib.fc |= 0x20; > >>>>>>>> + /* fallthrough */ > >>>>>>> > >>>>>>> This is correct, in case of an error we are also blocked. > >>>>>>> > >>>>>> > >>>>>> Agreed. This is definitely correct based on our architecture. > >>>>>> > >>>>>>>> case ZPCI_FS_BLOCKED: > >>>>>>>> fib.fc |= 0x40; > >>>>>>>> + /* fallthrough */ > >>>>>>> > >>>>>>> I think this is also correct, but it would be good if Collin could verify. > >>>>>>> > >>>>>> > >>>>>> I failed to find anything to support setting the function control > >>>>>> enabled bit when the function state is in error / blocked. I'm > >>>>>> assuming this might be some QEMU hack to get things working? I'll have > >>>>>> to dive further to understand why this was done this way, as it doesn't > >>>>>> align with how the s390x architecture is documented. It's confusing. > >>>>> > >>>>> Might this also be a real issue? Not matching the architecture is not a > >>>>> good sign... > >>>> > >>>> Friendly ping. If we still want to have this patch or a fix in 4.1, we > >>>> need to find out soon... > >>>> > >>> > >>> Let's take it for now. > >>> > >>> Acked-by: Collin Walling > >>> > >> > >> Just to be clear: You think that the current code is correct AFAYCS? > > > > I also looked into this again. > > There is a possibility to also be in disabled state. > > From what I can see, it makes sense that blocked and error belong to the enable state > > so the patch seems correct. > > > > Yes I agree. The material I referenced required me to look over a few > times and ask around a bit. The patch is good. Apologies for my > ambiguous response. > Ok, thanks for the clarification. Queued now.