Date: Fri, 19 Apr 2013 11:46:03 -0400 From: Tycho Nightingale <tycho.nightingale@pluribusnetworks.com> To: freebsd-virtualization@freebsd.org Subject: direct descriptor support for virtio block device Message-ID: <4FC78CC2-AAF3-4802-ACFC-3F3281DC45DE@pluribusnetworks.com>
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The current virtio block device advertises support for the indirect =
descriptors feature yet is unable to cope if the guest elects not to use =
them. Attached is a patch for direct descriptors along with an =
implementation of device reset.
Tycho
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diff -r 7ec7f1183c3c usr.sbin/bhyve/pci_virtio_block.c
--- a/usr.sbin/bhyve/pci_virtio_block.c Thu Apr 18 07:43:45 2013 -0400
+++ b/usr.sbin/bhyve/pci_virtio_block.c Fri Apr 19 11:08:32 2013 -0400
@@ -187,6 +187,13 @@
{
if (value == 0) {
DPRINTF(("vtblk: device reset requested !\n"));
+ sc->vbsc_isr = 0;
+ sc->msix_table_idx_req = VIRTIO_MSI_NO_VECTOR;
+ sc->msix_table_idx_cfg = VIRTIO_MSI_NO_VECTOR;
+ sc->vbsc_features = 0;
+ sc->vbsc_pfn = 0;
+ sc->vbsc_lastq = 0;
+ memset(&sc->vbsc_q, 0, sizeof(struct vring_hqueue));
}
sc->vbsc_status = value;
@@ -203,9 +210,8 @@
int i;
int err;
int iolen;
- int nsegs;
int uidx, aidx, didx;
- int writeop, type;
+ int indirect, writeop, type;
off_t offset;
uidx = *hq->hq_used_idx;
@@ -215,30 +221,21 @@
vd = &hq->hq_dtable[didx];
- /*
- * Verify that the descriptor is indirect, and obtain
- * the pointer to the indirect descriptor.
- * There has to be space for at least 3 descriptors
- * in the indirect descriptor array: the block header,
- * 1 or more data descriptors, and a status byte.
- */
- assert(vd->vd_flags & VRING_DESC_F_INDIRECT);
+ indirect = ((vd->vd_flags & VRING_DESC_F_INDIRECT) != 0);
- nsegs = vd->vd_len / sizeof(struct virtio_desc);
- assert(nsegs >= 3);
- assert(nsegs < VTBLK_MAXSEGS + 2);
-
- vid = paddr_guest2host(vtblk_ctx(sc), vd->vd_addr, vd->vd_len);
- assert((vid->vd_flags & VRING_DESC_F_INDIRECT) == 0);
+ if (indirect) {
+ vid = paddr_guest2host(vtblk_ctx(sc), vd->vd_addr, vd->vd_len);
+ vd = &vid[0];
+ }
/*
* The first descriptor will be the read-only fixed header
*/
- vbh = paddr_guest2host(vtblk_ctx(sc), vid[0].vd_addr,
+ vbh = paddr_guest2host(vtblk_ctx(sc), vd->vd_addr,
sizeof(struct virtio_blk_hdr));
- assert(vid[0].vd_len == sizeof(struct virtio_blk_hdr));
- assert(vid[0].vd_flags & VRING_DESC_F_NEXT);
- assert((vid[0].vd_flags & VRING_DESC_F_WRITE) == 0);
+ assert(vd->vd_len == sizeof(struct virtio_blk_hdr));
+ assert(vd->vd_flags & VRING_DESC_F_NEXT);
+ assert((vd->vd_flags & VRING_DESC_F_WRITE) == 0);
/*
* XXX
@@ -253,14 +250,21 @@
/*
* Build up the iovec based on the guest's data descriptors
*/
- for (i = 1, iolen = 0; i < nsegs - 1; i++) {
- iov[i-1].iov_base = paddr_guest2host(vtblk_ctx(sc),
- vid[i].vd_addr, vid[i].vd_len);
- iov[i-1].iov_len = vid[i].vd_len;
- iolen += vid[i].vd_len;
+ for (i = 1, iolen = 0; i <= VTBLK_MAXSEGS + 1; i++) {
+ if (indirect) {
+ vd = &vid[i];
+ } else {
+ vd = &hq->hq_dtable[vd->vd_next];
+ }
- assert(vid[i].vd_flags & VRING_DESC_F_NEXT);
- assert((vid[i].vd_flags & VRING_DESC_F_INDIRECT) == 0);
+ if ((vd->vd_flags & VRING_DESC_F_NEXT) == 0)
+ break;
+
+ iov[i - 1].iov_base = paddr_guest2host(vtblk_ctx(sc),
+ vd->vd_addr,
+ vd->vd_len);
+ iov[i - 1].iov_len = vd->vd_len;
+ iolen += vd->vd_len;
/*
* - write op implies read-only descriptor,
@@ -268,58 +272,35 @@
* therefore test the inverse of the descriptor bit
* to the op.
*/
- assert(((vid[i].vd_flags & VRING_DESC_F_WRITE) == 0) ==
+ assert(((vd->vd_flags & VRING_DESC_F_WRITE) == 0) ==
writeop);
}
/* Lastly, get the address of the status byte */
- status = paddr_guest2host(vtblk_ctx(sc), vid[nsegs - 1].vd_addr, 1);
- assert(vid[nsegs - 1].vd_len == 1);
- assert((vid[nsegs - 1].vd_flags & VRING_DESC_F_NEXT) == 0);
- assert(vid[nsegs - 1].vd_flags & VRING_DESC_F_WRITE);
+ status = paddr_guest2host(vtblk_ctx(sc), vd->vd_addr, 1);
+ assert(vd->vd_len == 1);
+ assert((vd->vd_flags & VRING_DESC_F_NEXT) == 0);
+ assert(vd->vd_flags & VRING_DESC_F_WRITE);
DPRINTF(("virtio-block: %s op, %d bytes, %d segs, offset %ld\n\r",
- writeop ? "write" : "read", iolen, nsegs - 2, offset));
+ writeop ? "write" : "read", iolen, i - 1, offset));
if (writeop){
- err = pwritev(sc->vbsc_fd, iov, nsegs - 2, offset);
+ err = pwritev(sc->vbsc_fd, iov, i - 1, offset);
} else {
- err = preadv(sc->vbsc_fd, iov, nsegs - 2, offset);
+ err = preadv(sc->vbsc_fd, iov, i - 1, offset);
}
*status = err < 0 ? VTBLK_S_IOERR : VTBLK_S_OK;
/*
- * Return the single indirect descriptor back to the host
+ * Return the single descriptor back to the host
*/
vu = &hq->hq_used_ring[uidx % hq->hq_size];
vu->vu_idx = didx;
vu->vu_tlen = 1;
hq->hq_cur_aidx++;
*hq->hq_used_idx += 1;
-}
-
-static void
-pci_vtblk_qnotify(struct pci_vtblk_softc *sc)
-{
- struct vring_hqueue *hq = &sc->vbsc_q;
- int i;
- int ndescs;
-
- /*
- * Calculate number of ring entries to process
- */
- ndescs = hq_num_avail(hq);
-
- if (ndescs == 0)
- return;
-
- /*
- * Run through all the entries, placing them into iovecs and
- * sending when an end-of-packet is found
- */
- for (i = 0; i < ndescs; i++)
- pci_vtblk_proc(sc, hq);
/*
* Generate an interrupt if able
@@ -332,7 +313,21 @@
pci_generate_msi(sc->vbsc_pi, 0);
}
}
-
+}
+
+static void
+pci_vtblk_qnotify(struct pci_vtblk_softc *sc)
+{
+ struct vring_hqueue *hq = &sc->vbsc_q;
+ int ndescs;
+
+ while ((ndescs = hq_num_avail(hq)) != 0) {
+ /*
+ * Run through all the entries, placing them into iovecs and
+ * sending when an end-of-packet is found
+ */
+ pci_vtblk_proc(sc, hq);
+ }
}
static void
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