Re: kern/57304: Recent updates to virtio trigger KASSERT with virtio_mmio on aarch64

[Shoichi Yamaguchi <yamaguchi%netbsd.org@localhost>]

The following reply was made to PR kern/57304; it has been noted by GNATS.

From: Shoichi Yamaguchi <yamaguchi%netbsd.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: yamaguchi%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, 
	skrll%netbsd.org@localhost
Subject: Re: kern/57304: Recent updates to virtio trigger KASSERT with
 virtio_mmio on aarch64
Date: Wed, 29 Mar 2023 13:25:16 +0900

 On Tue, Mar 28, 2023 at 3:10=E2=80=AFPM Nick Hudson <nick.hudson%gmx.co.uk@localhost>=
  wrote:
 >
 >  Bisecting shows this change as the first bad commit
 >
 >  Author: yamaguchi <yamaguchi%NetBSD.org@localhost>
 >  Date:   Thu Mar 23 03:55:11 2023 +0000
 >
 >       Added functions to set interrupt handler and index into virtqueue
 >
 
 Thank you for your bisecting. It was very helpful for me.
 Could you apply the following patch?
 
 ----- patch -----
 diff --git a/sys/dev/pci/virtio.c b/sys/dev/pci/virtio.c
 index bfe3b28d6a92..a4938a701024 100644
 --- a/sys/dev/pci/virtio.c
 +++ b/sys/dev/pci/virtio.c
 @@ -765,7 +765,7 @@ int
  virtio_alloc_vq(struct virtio_softc *sc, struct virtqueue *vq,
      int maxsegsize, int maxnsegs, const char *name)
  {
 - bus_size_t size_desc, size_avail, size_used, size_indirect;
 + bus_size_t size_used, size_indirect;
   bus_size_t allocsize =3D 0, size_desc_avail;
   int rsegs, r, hdrlen;
   unsigned int vq_num;
 @@ -782,16 +782,17 @@ virtio_alloc_vq(struct virtio_softc *sc, struct
 virtqueue *vq,
 
   hdrlen =3D sc->sc_active_features & VIRTIO_F_RING_EVENT_IDX ? 3 : 2;
 
 - size_desc =3D sizeof(vq->vq_desc[0]) * vq_num;
 - size_avail =3D sizeof(uint16_t) * hdrlen
 -    + sizeof(vq->vq_avail[0].ring) * vq_num;
 - size_used =3D sizeof(uint16_t) *hdrlen
 -    + sizeof(vq->vq_used[0].ring) * vq_num;
 - size_indirect =3D (sc->sc_indirect && maxnsegs >=3D MINSEG_INDIRECT) ?
 -    sizeof(struct vring_desc) * maxnsegs * vq_num : 0;
 -
 - size_desc_avail =3D VIRTQUEUE_ALIGN(size_desc + size_avail);
 - size_used =3D VIRTQUEUE_ALIGN(size_used);
 + size_desc_avail =3D VIRTQUEUE_ALIGN(
 +    sizeof(struct vring_desc) * vq_num
 +    + sizeof(uint16_t) * (hdrlen + vq_num));
 + size_used =3D VIRTQUEUE_ALIGN(
 +    sizeof(uint16_t) * hdrlen
 +    + sizeof(struct vring_used_elem) * vq_num);
 + if (sc->sc_indirect && maxnsegs >=3D MINSEG_INDIRECT) {
 + size_indirect =3D sizeof(struct vring_desc) * maxnsegs * vq_num;
 + } else {
 + size_indirect =3D 0;
 + }
 
   allocsize =3D size_desc_avail + size_used + size_indirect;
 
 @@ -836,24 +837,22 @@ virtio_alloc_vq(struct virtio_softc *sc, struct
 virtqueue *vq,
   vq->vq_maxsegsize =3D maxsegsize;
   vq->vq_maxnsegs =3D maxnsegs;
 
 -#define VIRTIO_PTR(base, offset) (void *)((intptr_t)(base) + (offset))
 - /* initialize vring pointers */
 - vq->vq_desc =3D VIRTIO_PTR(vq->vq_vaddr, 0);
 - vq->vq_availoffset =3D size_desc;
 - vq->vq_avail =3D VIRTIO_PTR(vq->vq_vaddr, vq->vq_availoffset);
 - vq->vq_used_event =3D VIRTIO_PTR(vq->vq_avail,
 -    offsetof(struct vring_avail, ring[vq_num]));
 + vq->vq_availoffset =3D sizeof(struct vring_desc) * vq_num;
   vq->vq_usedoffset =3D size_desc_avail;
 - vq->vq_used =3D VIRTIO_PTR(vq->vq_vaddr, vq->vq_usedoffset);
 - vq->vq_avail_event =3D VIRTIO_PTR(vq->vq_used,
 -    offsetof(struct vring_used, ring[vq_num]));
 +
 + vq->vq_desc =3D vq->vq_vaddr;
 + vq->vq_avail =3D (void *)(((char *)vq->vq_desc) + vq->vq_availoffset);
 + vq->vq_used_event =3D (uint16_t *)((char *)vq->vq_avail +
 +    offsetof(struct vring_avail, ring[vq->vq_num]));
 + vq->vq_used =3D (void *)(((char *)vq->vq_desc) + vq->vq_usedoffset);
 + vq->vq_avail_event =3D (uint16_t *)((char *)vq->vq_used +
 +    offsetof(struct vring_used, ring[vq->vq_num]));
 
   if (size_indirect > 0) {
   vq->vq_indirectoffset =3D size_desc_avail + size_used;
 - vq->vq_indirect =3D VIRTIO_PTR(vq->vq_vaddr,
 -    vq->vq_indirectoffset);
 + vq->vq_indirect =3D (void *)(((char *)vq->vq_desc)
 +    + vq->vq_indirectoffset);
   }
 -#undef VIRTIO_PTR
 
   /* free slot management */
   vq->vq_entries =3D kmem_zalloc(sizeof(struct vq_entry) * vq_num,