On Wed, 10 Jul 2019 10:20:41 +0200
Cornelia Huck <coh...@redhat.com> wrote:
> On Tue, 9 Jul 2019 18:55:34 -0400
> Collin Walling <wall...@linux.ibm.com> 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 <s...@weilnetz.de>
> > >> Fixes: 5d1abf234462 ("s390x/pci: enforce zPCI state checking")
> > >> Signed-off-by: Cornelia Huck <coh...@redhat.com>
> > >
> > > 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...
>
> >
> > Functionally, this doesn't change anything... so I'll at least give it
> > an ACK for now and investigate this further.
>
> I prefer to hold off on this patch for now, unless we're really sure
> that the code does not have a problem here. Actually documenting
> something that might be wrong does not sound like the right thing to
> do :/
>
> >
> > >> case ZPCI_FS_ENABLED:
> > >> fib.fc |= 0x80;
> > >> if (pbdev->iommu->enabled) {
> > >>
> > >
> > >
> >
> > Acked-by: Collin Walling <wall...@linux.ibm.com>
> >
> > Side note: is there somewhere that I could access this bug report? :)
>
> It's the build log with the extra warnings in
> https://qemu.weilnetz.de/results/build-20190708.txt (referenced in
> <591d71a5-5b10-ab22-4751-01da8613d...@weilnetz.de> on qemu-devel).
