Re: [PATCH v4] target/s390x: Implement the MVPG condition-code-option bit

[David Hildenbrand]

On 03.03.21 22:36, Richard Henderson wrote:
> On 3/3/21 1:22 PM, David Hildenbrand wrote:
> > > Am 03.03.2021 um 22:19 schrieb Richard Henderson <richard.henderson@linaro.org>:
> > >
> > > On 3/3/21 1:11 PM, David Hildenbrand wrote:
> > > > MMIO on s390x? :)
> > >
> > > hw/s390x/s390-pci-bus.c, memory_region_init_io*().
> >
> > ... part of system address space where a CPU could stumble over it?
>
> Impossible to tell within 3 layers of object wrappers.  :-(
> I suppose I have no idea how "pci" was hacked onto s390x.

You've used the right words to describe "pci" (!) on s390x.

IIRC, there is no MMIO: configuration space accesses etc. are performed 
using special access instructions - which will "emulate" the MMIO access 
performed on other archs via simple read/write instructions.

Ordinary instructions (e.g., mvpg) that operate on the system address 
space should never stumble over MMIO regions - because that concept does 
not exist on s390x.

--
Thanks,

David / dhildenb