I tested the patch you provided on my local qemu install and it booted successfully.
Index: sys/dev/pv/vioscsi.c > =================================================================== > RCS file: /cvs/src/sys/dev/pv/vioscsi.c,v > retrieving revision 1.30 > diff -u -p -u -p -r1.30 vioscsi.c > --- sys/dev/pv/vioscsi.c 16 Apr 2022 19:19:59 -0000 1.30 > +++ sys/dev/pv/vioscsi.c 25 Apr 2023 12:51:16 -0000 > @@ -296,6 +296,7 @@ vioscsi_req_done(struct vioscsi_softc *s > struct scsi_xfer *xs = vr->vr_xs; > DPRINTF("vioscsi_req_done: enter vr: %p xs: %p\n", vr, xs); > + if (xs == NULL) return; > int isread = !!(xs->flags & SCSI_DATA_IN); > bus_dmamap_sync(vsc->sc_dmat, vr->vr_control, > offsetof(struct vioscsi_req, vr_req), > > -- Aaron Mason - Programmer, open source addict I've taken my software vows - for beta or for worse