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vtblk: Fix dumping

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Now that vtblk uses busdma, it keeps important information inside its
request structures.  The functions used for kernel dumps synthesize
their own request structures rather than using structures initialized
with the necessary bits for busdma.

Add busdma-bypass paths.  Since dumping writes contiguous blocks of
physical memory, vtblk doesn't need busdma in that case.

Reported by:	glebius
Tested by:	glebius
Differential Revision:	https://reviews.freebsd.org/D37243
This commit is contained in:
Colin Percival 2022-11-02 18:55:12 -07:00
parent a6346c02f6
commit 75549de770
1 changed files with 17 additions and 3 deletions
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20
sys/dev/virtio/block/virtio_blk.c
View file

@ -992,9 +992,12 @@ vtblk_request_execute(struct vtblk_request *req, int flags)
/*
* Call via bus_dmamap_load_bio or directly depending on whether we
* have a buffer we need to map.
* have a buffer we need to map. If we don't have a busdma map,
* try to perform the I/O directly and hope that it works (this will
* happen when dumping).
*/
if (bp->bio_cmd == BIO_READ || bp->bio_cmd == BIO_WRITE) {
if ((req->vbr_mapp != NULL) &&
(bp->bio_cmd == BIO_READ || bp->bio_cmd == BIO_WRITE)) {
error = bus_dmamap_load_bio(sc->vtblk_dmat, req->vbr_mapp,
req->vbr_bp, vtblk_request_execute_cb, req, flags);
if (error == EINPROGRESS) {
@ -1080,6 +1083,15 @@ vtblk_request_execute_cb(void * callback_arg, bus_dma_segment_t * segs,
}
}
/* Special handling for dump, which bypasses busdma. */
if (req->vbr_mapp == NULL) {
error = sglist_append_bio(sg, bp);
if (error || sg->sg_nseg == sg->sg_maxseg) {
panic("%s: bio %p data buffer too big %d",
__func__, bp, error);
}
}
/* BIO_READ means the host writes into our buffer. */
if (bp->bio_cmd == BIO_READ)
writable = sg->sg_nseg - 1;
@ -1130,7 +1142,7 @@ vtblk_request_execute_cb(void * callback_arg, bus_dma_segment_t * segs,
virtqueue_notify(vq);
out:
if (error)
if (error && (req->vbr_mapp != NULL))
bus_dmamap_unload(sc->vtblk_dmat, req->vbr_mapp);
out1:
if (error && req->vbr_requeue_on_error)
@ -1505,6 +1517,7 @@ vtblk_dump_write(struct vtblk_softc *sc, void *virtual, off_t offset,
struct vtblk_request *req;
req = &sc->vtblk_dump_request;
req->vbr_sc = sc;
req->vbr_ack = -1;
req->vbr_hdr.type = vtblk_gtoh32(sc, VIRTIO_BLK_T_OUT);
req->vbr_hdr.ioprio = vtblk_gtoh32(sc, 1);
@ -1527,6 +1540,7 @@ vtblk_dump_flush(struct vtblk_softc *sc)
struct vtblk_request *req;
req = &sc->vtblk_dump_request;
req->vbr_sc = sc;
req->vbr_ack = -1;
req->vbr_hdr.type = vtblk_gtoh32(sc, VIRTIO_BLK_T_FLUSH);
req->vbr_hdr.ioprio = vtblk_gtoh32(sc, 1);