Re: [PATCH v3] hw/audio/virtio-snd: Use device endianness instead of target one

[Philippe Mathieu-Daudé]

On 22/4/24 23:02, Michael S. Tsirkin wrote:
> On Mon, Apr 22, 2024 at 04:20:56PM +0200, Philippe Mathieu-Daudé wrote:
> > Since VirtIO devices can change endianness at runtime,
> > we need to use the device endianness, not the target
> > one.
> >
> > Cc: qemu-stable@nongnu.org
> > Fixes: eb9ad377bb ("virtio-sound: handle control messages and streams")
> > Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
>
>
>
> This is all completely bogus. Virtio SND is from Virtio 1.0 only.
> It is unconditionally little endian.

Oh, then the fix is as simple as:

 -    as->endianness = target_words_bigendian() ? 1 : 0;
 +    as->endianness = 0; /* VIRTIO 1.0: always LE. */

> If it's not it's a guest bug pls just fix it there.
>
>
> > ---
> > v2: Use virtio_is_big_endian()
> > v3: Remove "hw/core/cpu.h
> > ---
> >   hw/audio/virtio-snd.c | 9 +++++----
> >   1 file changed, 5 insertions(+), 4 deletions(-)
> >
> > diff --git a/hw/audio/virtio-snd.c b/hw/audio/virtio-snd.c
> > index c80b58bf5d..939cd78026 100644
> > --- a/hw/audio/virtio-snd.c
> > +++ b/hw/audio/virtio-snd.c
> > @@ -24,7 +24,6 @@
> >   #include "trace.h"
> >   #include "qapi/error.h"
> >   #include "hw/audio/virtio-snd.h"
> > -#include "hw/core/cpu.h"
> >   
> >   #define VIRTIO_SOUND_VM_VERSION 1
> >   #define VIRTIO_SOUND_JACK_DEFAULT 0
> > @@ -395,13 +394,15 @@ static uint32_t virtio_snd_get_qemu_freq(uint32_t rate)
> >    * Get QEMU Audiosystem compatible audsettings from virtio based pcm stream
> >    * params.
> >    */
> > -static void virtio_snd_get_qemu_audsettings(audsettings *as,
> > +static void virtio_snd_get_qemu_audsettings(VirtIOSound *s, audsettings *as,
> >                                               virtio_snd_pcm_set_params *params)
> >   {
> > +    VirtIODevice *vdev = VIRTIO_DEVICE(s);
> > +
> >       as->nchannels = MIN(AUDIO_MAX_CHANNELS, params->channels);
> >       as->fmt = virtio_snd_get_qemu_format(params->format);
> >       as->freq = virtio_snd_get_qemu_freq(params->rate);
> > -    as->endianness = target_words_bigendian() ? 1 : 0;
> > +    as->endianness = virtio_is_big_endian(vdev) ? 1 : 0;
> >   }
> >   
> >   /*
> > @@ -464,7 +465,7 @@ static uint32_t virtio_snd_pcm_prepare(VirtIOSound *s, 
> > uint32_t stream_id)
> >           s->pcm->streams[stream_id] = stream;
> >       }
> >   
> > -    virtio_snd_get_qemu_audsettings(&as, params);
> > +    virtio_snd_get_qemu_audsettings(s, &as, params);
> >       stream->info.direction = stream_id < s->snd_conf.streams / 2 +
> >           (s->snd_conf.streams & 1) ? VIRTIO_SND_D_OUTPUT : VIRTIO_SND_D_INPUT;
> >       stream->info.hdr.hda_fn_nid = VIRTIO_SOUND_HDA_FN_NID;
> > --
> > 2.41.0