Re: [PATCH v3 1/4] s390x/css: Introduce an ESW struct

[Cornelia Huck]

On Wed, Jun 16 2021, Eric Farman <farman@linux.ibm.com> wrote:

> On Wed, 2021-06-16 at 11:46 +0200, Cornelia Huck wrote:
>> On Wed, Jun 16 2021, Eric Farman <farman@linux.ibm.com> wrote:
>> 
>> > The Interrupt Response Block is comprised of several other
>> > structures concatenated together, but only the 12-byte
>> > Subchannel-Status Word (SCSW) is defined as a proper struct.
>> > Everything else is a simple array of 32-bit words.
>> > 
>> > Let's define a proper struct for the 20-byte Extended-Status
>> > Word (ESW) so that we can make good decisions about the sense
>> > data that would go into the ECW area for virtual vs
>> > passthrough devices.
>> > 
>> > Signed-off-by: Eric Farman <farman@linux.ibm.com>
>> > ---
>> >  hw/s390x/css.c            | 19 +++++++++++++------
>> >  include/hw/s390x/ioinst.h | 12 +++++++++++-
>> >  2 files changed, 24 insertions(+), 7 deletions(-)
>> > 
>> 
>> (...)
>> 
>> > diff --git a/include/hw/s390x/ioinst.h b/include/hw/s390x/ioinst.h
>> > index c6737a30d4..9613e0ccbb 100644
>> > --- a/include/hw/s390x/ioinst.h
>> > +++ b/include/hw/s390x/ioinst.h
>> > @@ -123,10 +123,20 @@ typedef struct SCHIB {
>> >      uint8_t mda[4];
>> >  } QEMU_PACKED SCHIB;
>> >  
>> > +/* extended-status word */
>> > +typedef struct ESW {
>> > +   uint32_t sublog;
>> > +   uint32_t erw;
>> > +   uint64_t f_addr;
>> > +   uint32_t s_addr;
>> > +} QEMU_PACKED ESW;
>> 
>> Strictly speaking, that's a format 0 esw. 
>
> True. I thought I put that in there, but I guess not. I can make a
> clarification.

A short comment would be fine.

>
>> Doesn't matter too much in the
>> end, I think:
>> - erw is always the same
>> - f_addr and s_addr are always 0 for the other formats
>> - 'sublog' is always a u32 with the lpum in the same place (which we
>>   always set to 0x80 for virtual subchannels, as they have only one
>> path)
>> 
>
> Yeah, I didn't want to get into the different formats' word 0. Since
> the lpum is common to all, what if I just rename 'sublog' to 'word0'
> and add some comments for f_addr and s_addr as only being applicable to
> Format 0?

Works for me.

>
>> > +
>> > +#define ESW_ERW_SENSE 0x01000000
>> > +
>> >  /* interruption response block */
>> >  typedef struct IRB {
>> >      SCSW scsw;
>> > -    uint32_t esw[5];
>> > +    ESW esw;
>> >      uint32_t ecw[8];
>> >      uint32_t emw[8];
>> >  } IRB;