Re: [PATCH v4 1/4] s390x/css: Introduce an ESW struct

From: Eric Farman <farman@linux.ibm.com>
To: Cornelia Huck <cohuck@redhat.com>,
	qemu-devel@nongnu.org, qemu-s390x@nongnu.org
Cc: Thomas Huth <thuth@redhat.com>,
	Matthew Rosato <mjrosato@linux.ibm.com>,
	David Hildenbrand <david@redhat.com>,
	Richard Henderson <richard.henderson@linaro.org>,
	Halil Pasic <pasic@linux.ibm.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Alex Williamson <alex.williamson@redhat.com>
Subject: Re: [PATCH v4 1/4] s390x/css: Introduce an ESW struct
Date: Fri, 18 Jun 2021 08:55:18 -0400	[thread overview]
Message-ID: <adca6d5e3c3037da7923489fa28fcd34be099e75.camel@linux.ibm.com> (raw)
In-Reply-To: <874kdvpchd.fsf@redhat.com>

On Fri, 2021-06-18 at 14:46 +0200, Cornelia Huck wrote:
> On Fri, Jun 18 2021, Cornelia Huck <cohuck@redhat.com> wrote:
> 
> > On Fri, Jun 18 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..e7ab401781 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;
> > >  
> > > +/* format-0 extended-status word */
> > > +typedef struct ESW {
> > > +   uint32_t word0;
> > > +   uint32_t erw;
> > > +   uint64_t f_addr;     /* Zeros for other ESW formats */
> > > +   uint32_t s_addr;     /* Zeros for other ESW formats */
> > > +} QEMU_PACKED ESW;
> > 
> > Eww, this fails with mingw:
> > https://gitlab.com/cohuck/qemu/-/jobs/1358335494
> > 
> > i686-w64-mingw32-gcc -Ilibcommon.fa.p -I../slirp -I../slirp/src
> > -I../dtc/libfdt -I../capstone/include/capstone -I. -Iqapi -Itrace
> > -Iui -Iui/shader -I/usr/i686-w64-mingw32/sys-root/mingw/include
> > -I/usr/i686-w64-mingw32/sys-root/mingw/include/glib-2.0
> > -I/usr/i686-w64-mingw32/sys-root/mingw/lib/glib-2.0/include
> > -I/usr/i686-w64-mingw32/sys-root/mingw/include/gtk-3.0 -I/usr/i686-
> > w64-mingw32/sys-root/mingw/include/cairo -I/usr/i686-w64-
> > mingw32/sys-root/mingw/include/pango-1.0 -I/usr/i686-w64-
> > mingw32/sys-root/mingw/include/fribidi -I/usr/i686-w64-mingw32/sys-
> > root/mingw/include/harfbuzz -I/usr/i686-w64-mingw32/sys-
> > root/mingw/include/atk-1.0 -I/usr/i686-w64-mingw32/sys-
> > root/mingw/include/pixman-1 -I/usr/i686-w64-mingw32/sys-
> > root/mingw/include/freetype2 -I/usr/i686-w64-mingw32/sys-
> > root/mingw/include/libpng16 -I/usr/i686-w64-mingw32/sys-
> > root/mingw/include/gdk-pixbuf-2.0 -I/usr/i686-w64-mingw32/sys-
> > root/mingw/lib/libffi-3.1/include -I/usr/i686-w64-mingw32/sys-
> > root/mingw/include/p11-kit-1 -I/usr/i686-w64-mingw32/sys-
> > root/mingw/include/SDL2 -fdiagnostics-color=auto -pipe -Wall
> > -Winvalid-pch -Werror -std=gnu99 -O2 -g -iquote . -iquote
> > /builds/cohuck/qemu -iquote /builds/cohuck/qemu/include -iquote
> > /builds/cohuck/qemu/disas/libvixl -iquote
> > /builds/cohuck/qemu/tcg/i386 -mms-bitfields -U_FORTIFY_SOURCE
> > -D_FORTIFY_SOURCE=2 -m32 -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64
> > -D_LARGEFILE_SOURCE -Wstrict-prototypes -Wredundant-decls -Wundef
> > -Wwrite-strings -Wmissing-prototypes -fno-strict-aliasing -fno-
> > common -fwrapv -Wold-style-declaration -Wold-style-definition
> > -Wtype-limits -Wformat-security -Wformat-y2k -Winit-self -Wignored-
> > qualifiers -Wempty-body -Wnested-externs -Wendif-labels
> > -Wexpansion-to-defined -Wimplicit-fallthrough=2 -Wno-missing-
> > include-dirs -Wno-shift-negative-value -Wno-psabi -fstack-
> > protector-strong -Dmain=SDL_main -Wno-undef -mms-bitfields -mms-
> > bitfields -mms-bitfields -MD -MQ libcommon.fa.p/hw_s390x_virtio-
> > ccw-gpu.c.obj -MF libcommon.fa.p/hw_s390x_virtio-ccw-gpu.c.obj.d -o
> > libcommon.fa.p/hw_s390x_virtio-ccw-gpu.c.obj -c ../hw/s390x/virtio-
> > ccw-gpu.c
> > In file included from /usr/i686-w64-mingw32/sys-
> > root/mingw/include/winsock2.h:54,
> >                  from /builds/cohuck/qemu/include/sysemu/os-
> > win32.h:29,
> >                  from /builds/cohuck/qemu/include/qemu/osdep.h:135,
> >                  from ../hw/s390x/virtio-ccw-gpu.c:11:
> > /builds/cohuck/qemu/include/hw/s390x/ioinst.h:131:13: error:
> > expected ':', ',', ';', '}' or '__attribute__' before '.' token
> >   131 |    uint32_t s_addr;     /* Zeros for other ESW formats */
> >       |             ^~~~~~
> 
> It seems to be the name that is tripping it; if I rename it to
> sec_addr
> and the preceding field to fail_addr, the build passes.

I was just wondering if it might have been the underscore directly, not
that it was a single letter before the underscore. Weird.

> 
> Anyone know why that is? And if renaming is unavoidable, are
> fail_addr
> and sec_addr ok, or can we find better names?

Since they're zero for Format-!0 ESWs, and regardless we don't fill
them in anyway, could we just make them wordN and change the comment to
give the descriptive name?

 /* format-0 extended-status word */
 typedef struct ESW {
-   uint32_t
word0;
+   uint32_t word0;      /* subchannel logout for format 0 */

uint32_t erw;
-   uint64_t f_addr;     /* Zeros for other ESW formats */
-   uint32_t s_addr;     /* Zeros for other ESW formats */
+   uint64_t
word2;      /* failing-storage address for format 0 */
+   uint32_t
word4;      /* scondary-CCW address for format 0 */
 } QEMU_PACKED ESW;

> 
> > In file included from /builds/cohuck/qemu/include/qemu/osdep.h:37,
> >                  from ../hw/s390x/virtio-ccw-gpu.c:11:
> > /builds/cohuck/qemu/include/qemu/compiler.h:80:36: error: static
> > assertion failed: "size of IRB is wrong"
> >    80 | #define QEMU_BUILD_BUG_MSG(x, msg) _Static_assert(!(x),
> > msg)
> >       |                                    ^~~~~~~~~~~~~~
> > /builds/cohuck/qemu/include/hw/s390x/ioinst.h:143:1: note: in
> > expansion of macro 'QEMU_BUILD_BUG_MSG'
> >   143 | QEMU_BUILD_BUG_MSG(sizeof(IRB) != 96, "size of IRB is
> > wrong");
> >       | ^~~~~~~~~~~~~~~~~~
> > 
> 
> These were just follow-on errors.
> 
> > > +
> > > +#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;