Module Name: src
Committed By: jdolecek
Date: Sun Apr 12 20:17:36 UTC 2020
Modified Files:
src/sys/arch/xen/xen: xbd_xenbus.c
Log Message:
convert to bus_dma(9)
simplify and fix error handling in xbd_handler(), expect backend
to not use the grant once request is finished, and avoid leaking
bounce buffer when the request using it happens to end with error
in xbd_diskstart() only do the RING_PUSH_REQUESTS_AND_CHECK_NOTIFY()
when actually the request was pushed successfully
To generate a diff of this commit:
cvs rdiff -u -r1.104 -r1.105 src/sys/arch/xen/xen/xbd_xenbus.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/arch/xen/xen/xbd_xenbus.c
diff -u src/sys/arch/xen/xen/xbd_xenbus.c:1.104 src/sys/arch/xen/xen/xbd_xenbus.c:1.105
--- src/sys/arch/xen/xen/xbd_xenbus.c:1.104 Sun Apr 12 18:14:09 2020
+++ src/sys/arch/xen/xen/xbd_xenbus.c Sun Apr 12 20:17:36 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: xbd_xenbus.c,v 1.104 2020/04/12 18:14:09 jdolecek Exp $ */
+/* $NetBSD: xbd_xenbus.c,v 1.105 2020/04/12 20:17:36 jdolecek Exp $ */
/*
* Copyright (c) 2006 Manuel Bouyer.
@@ -50,7 +50,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: xbd_xenbus.c,v 1.104 2020/04/12 18:14:09 jdolecek Exp $");
+__KERNEL_RCSID(0, "$NetBSD: xbd_xenbus.c,v 1.105 2020/04/12 20:17:36 jdolecek Exp $");
#include "opt_xen.h"
@@ -100,10 +100,10 @@ __KERNEL_RCSID(0, "$NetBSD: xbd_xenbus.c
struct xbd_req {
SLIST_ENTRY(xbd_req) req_next;
uint16_t req_id; /* ID passed to backend */
+ bus_dmamap_t req_dmamap;
union {
struct {
grant_ref_t req_gntref[BLKIF_MAX_SEGMENTS_PER_REQUEST];
- int req_nr_segments; /* number of segments in this request */
struct buf *req_bp; /* buffer associated with this request */
void *req_data; /* pointer to the data buffer */
} req_rw;
@@ -114,7 +114,6 @@ struct xbd_req {
} u;
};
#define req_gntref u.req_rw.req_gntref
-#define req_nr_segments u.req_rw.req_nr_segments
#define req_bp u.req_rw.req_bp
#define req_data u.req_rw.req_data
#define req_sync u.req_sync
@@ -288,6 +287,16 @@ xbd_xenbus_attach(device_t parent, devic
evcnt_attach_dynamic(&sc->sc_cnt_map_unalign, EVCNT_TYPE_MISC,
NULL, device_xname(self), "map unaligned");
+ for (i = 0; i < XBD_RING_SIZE; i++) {
+ if (bus_dmamap_create(sc->sc_xbusd->xbusd_dmat,
+ XBD_MAX_XFER, BLKIF_MAX_SEGMENTS_PER_REQUEST,
+ PAGE_SIZE, PAGE_SIZE, BUS_DMA_WAITOK | BUS_DMA_ALLOCNOW,
+ &sc->sc_reqs[i].req_dmamap) != 0) {
+ aprint_error_dev(self, "can't alloc dma maps\n");
+ return;
+ }
+ }
+
/* resume shared structures and tell backend that we are ready */
if (xbd_xenbus_resume(self, PMF_Q_NONE) == false) {
uvm_km_free(kernel_map, (vaddr_t)ring, PAGE_SIZE,
@@ -371,6 +380,14 @@ xbd_xenbus_detach(device_t dev, int flag
uvm_km_free(kernel_map, (vaddr_t)sc->sc_ring.sring,
PAGE_SIZE, UVM_KMF_WIRED);
+ for (i = 0; i < XBD_RING_SIZE; i++) {
+ if (sc->sc_reqs[i].req_dmamap != NULL) {
+ bus_dmamap_destroy(sc->sc_xbusd->xbusd_dmat,
+ sc->sc_reqs[i].req_dmamap);
+ sc->sc_reqs[i].req_dmamap = NULL;
+ }
+ }
+
evcnt_detach(&sc->sc_cnt_map_unalign);
pmf_device_deregister(dev);
@@ -686,41 +703,38 @@ again:
continue;
}
- for (seg = xbdreq->req_nr_segments - 1; seg >= 0; seg--) {
- if (__predict_false(
- xengnt_status(xbdreq->req_gntref[seg]))) {
- aprint_verbose_dev(sc->sc_dksc.sc_dev,
- "grant still used by backend\n");
- sc->sc_ring.rsp_cons = i;
- xbdreq->req_nr_segments = seg + 1;
- goto done;
- }
+ for (seg = 0; seg < xbdreq->req_dmamap->dm_nsegs; seg++) {
+ /*
+ * We are not allowing persistent mappings, so
+ * expect the backend to release the grant
+ * immediately.
+ */
+ KASSERT(xengnt_status(xbdreq->req_gntref[seg]) == 0);
xengnt_revoke_access(xbdreq->req_gntref[seg]);
- xbdreq->req_nr_segments--;
}
- KASSERT(xbdreq->req_nr_segments == 0);
+
+ bus_dmamap_unload(sc->sc_xbusd->xbusd_dmat, xbdreq->req_dmamap);
bp = xbdreq->req_bp;
- KASSERT(bp != NULL);
+ KASSERT(bp != NULL && bp->b_data != NULL);
DPRINTF(("%s(%p): b_bcount = %ld\n", __func__,
bp, (long)bp->b_bcount));
+ if (__predict_false(bp->b_data != xbdreq->req_data))
+ xbd_unmap_align(xbdreq);
+ xbdreq->req_bp = xbdreq->req_data = NULL;
+
+ /* b_resid was set in dk_start, only override on error */
if (rep->status != BLKIF_RSP_OKAY) {
bp->b_error = EIO;
bp->b_resid = bp->b_bcount;
- goto next;
}
- /* b_resid was set in dk_start */
- if (__predict_false(
- xbdreq->req_data != NULL && bp->b_data != xbdreq->req_data))
- xbd_unmap_align(xbdreq);
-next:
- xbdreq->req_bp = NULL;
+
dk_done(&sc->sc_dksc, bp);
SLIST_INSERT_HEAD(&sc->sc_xbdreq_head, xbdreq, req_next);
}
-done:
+
xen_rmb();
sc->sc_ring.rsp_cons = i;
@@ -937,9 +951,8 @@ xbd_diskstart(device_t self, struct buf
struct xbd_xenbus_softc *sc = device_private(self);
struct xbd_req *xbdreq;
blkif_request_t *req;
- size_t bcount, off;
+ size_t off;
paddr_t ma;
- vaddr_t va;
int nsects, nbytes, seg;
int notify, error = 0;
int s;
@@ -947,19 +960,19 @@ xbd_diskstart(device_t self, struct buf
DPRINTF(("xbd_diskstart(%p): b_bcount = %ld\n",
bp, (long)bp->b_bcount));
+ s = splbio(); /* XXX SMP */
+
if (sc->sc_shutdown != BLKIF_SHUTDOWN_RUN) {
error = EIO;
- goto err;
+ goto out;
}
if (bp->b_rawblkno < 0 || bp->b_rawblkno > sc->sc_xbdsize) {
/* invalid block number */
error = EINVAL;
- goto err;
+ goto out;
}
- s = splbio(); /* XXX SMP */
-
if (__predict_false(
sc->sc_backend_status == BLKIF_STATE_SUSPENDED)) {
/* device is suspended, do not consume buffer */
@@ -997,6 +1010,16 @@ xbd_diskstart(device_t self, struct buf
}
}
+ if (__predict_false(bus_dmamap_load(sc->sc_xbusd->xbusd_dmat,
+ xbdreq->req_dmamap, xbdreq->req_data, bp->b_bcount, NULL,
+ BUS_DMA_NOWAIT) != 0)) {
+ printf("%s: %s: xengnt_grant_access failed",
+ device_xname(sc->sc_dksc.sc_dev), __func__);
+ error = EINVAL;
+ goto out;
+ }
+
+ /* We are now committed to the transfer */
SLIST_REMOVE_HEAD(&sc->sc_xbdreq_head, req_next);
req = RING_GET_REQUEST(&sc->sc_ring, sc->sc_ring.req_prod_pvt);
req->id = xbdreq->req_id;
@@ -1005,45 +1028,41 @@ xbd_diskstart(device_t self, struct buf
req->sector_number = bp->b_rawblkno;
req->handle = sc->sc_handle;
- va = (vaddr_t)xbdreq->req_data & ~PAGE_MASK;
- off = (vaddr_t)xbdreq->req_data & PAGE_MASK;
- bcount = bp->b_bcount;
bp->b_resid = 0;
- for (seg = 0; bcount > 0;) {
- pmap_extract_ma(pmap_kernel(), va, &ma);
- KASSERT((ma & (XEN_BSIZE - 1)) == 0);
- if (bcount > PAGE_SIZE - off)
- nbytes = PAGE_SIZE - off;
- else
- nbytes = bcount;
+ for (seg = 0; seg < xbdreq->req_dmamap->dm_nsegs; seg++) {
+ bus_dma_segment_t *dmaseg = &xbdreq->req_dmamap->dm_segs[seg];
+
+ ma = dmaseg->ds_addr;
+ off = ma & PAGE_MASK;
+ nbytes = dmaseg->ds_len;
nsects = nbytes >> XEN_BSHIFT;
+
req->seg[seg].first_sect = off >> XEN_BSHIFT;
- req->seg[seg].last_sect =
- (off >> XEN_BSHIFT) + nsects - 1;
- KASSERT(req->seg[seg].first_sect <=
- req->seg[seg].last_sect);
- KASSERT(req->seg[seg].last_sect < 8);
+ req->seg[seg].last_sect = (off >> XEN_BSHIFT) + nsects - 1;
+ KASSERT(req->seg[seg].first_sect <= req->seg[seg].last_sect);
+ KASSERT(req->seg[seg].last_sect < (PAGE_SIZE / XEN_BSIZE));
+
if (__predict_false(xengnt_grant_access(
- sc->sc_xbusd->xbusd_otherend_id, ma,
- (bp->b_flags & B_READ) == 0,
- &xbdreq->req_gntref[seg])))
- panic("xbd_diskstart: xengnt_grant_access"); /* XXX XXX !!! */
+ sc->sc_xbusd->xbusd_otherend_id,
+ (ma & ~PAGE_MASK), (bp->b_flags & B_READ) == 0,
+ &xbdreq->req_gntref[seg]))) {
+ printf("%s: %s: xengnt_grant_access failed",
+ device_xname(sc->sc_dksc.sc_dev), __func__);
+ error = EFAULT;
+ goto out;
+ }
+
req->seg[seg].gref = xbdreq->req_gntref[seg];
- seg++;
- KASSERT(seg <= BLKIF_MAX_SEGMENTS_PER_REQUEST);
- va += PAGE_SIZE;
- off = 0;
- bcount -= nbytes;
}
- xbdreq->req_nr_segments = req->nr_segments = seg;
+ req->nr_segments = seg;
sc->sc_ring.req_prod_pvt++;
-out:
RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&sc->sc_ring, notify);
if (notify)
hypervisor_notify_via_evtchn(sc->sc_evtchn);
+
+out:
splx(s); /* XXXSMP */
-err:
return error;
}
