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freebsd-nq/sys/dev/xen/blkfront/blkfront.c
Kenneth D. Merry c3fb2891f0 Fix a bug which causes a panic in daopen(). The panic is caused by 
a da(4) instance going away while GEOM is still probing it.

In this case, the GEOM disk class instance has been created by
disk_create(), and the taste of the disk is queued in the GEOM
event queue.

While that event is queued, the da(4) instance goes away.  When the
open call comes into the da(4) driver, it dereferences the freed
(but non-NULL) peripheral pointer provided by GEOM, which results
in a panic.

The solution is to add a callback to the GEOM disk code that is
called when all of its resources are cleaned up.  This is
implemented inside GEOM by adding an optional callback that is
called when all consumers have detached from a provider, and the
provider is about to be deleted.

scsi_cd.c,
scsi_da.c:	In the register routine for the cd(4) and da(4)
		routines, acquire a reference to the CAM peripheral
		instance just before we call disk_create().

		Use the new GEOM disk d_gone() callback to register
		a callback (dadiskgonecb()/cddiskgonecb()) that
		decrements the peripheral reference count once GEOM
		has finished cleaning up its resources.

		In the cd(4) driver, clean up open and close
		behavior slightly.  GEOM makes sure we only get one
		open() and one close call, so there is no need to
		set an open flag and decrement the reference count
		if we are not the first open.

		In the cd(4) driver, use cam_periph_release_locked()
		in a couple of error scenarios to avoid extra mutex
		calls.

geom.h:		Add a new, optional, providergone callback that
		is called when a provider is about to be deleted.

geom_disk.h:	Add a new d_gone() callback to the GEOM disk
		interface.

		Bump the DISK_VERSION to version 2.  This probably
		should have been done after a couple of previous
		changes, especially the addition of the d_getattr()
		callback.

geom_disk.c:	Add a providergone callback for the disk class,
		g_disk_providergone(), that calls the user's
		d_gone() callback if it exists.

		Bump the DISK_VERSION to 2.

geom_subr.c:	In g_destroy_provider(), call the providergone
		callback if it has been provided.

		In g_new_geomf(), propagate the class's
		providergone callback to the new geom instance.

blkfront.c:	Callers of disk_create() are supposed to pass in
		DISK_VERSION, not an explicit disk API version
		number.  Update the blkfront driver to do that.

disk.9:		Update the disk(9) man page to include information
		on the new d_gone() callback, as well as the
		previously added d_getattr() callback, d_descr
		field, and HBA PCI ID fields.

MFC after:	5 days
2012-06-24 04:29:03 +00:00

1429 lines
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/*
* XenBSD block device driver
*
* Copyright (c) 2009 Scott Long, Yahoo!
* Copyright (c) 2009 Frank Suchomel, Citrix
* Copyright (c) 2009 Doug F. Rabson, Citrix
* Copyright (c) 2005 Kip Macy
* Copyright (c) 2003-2004, Keir Fraser & Steve Hand
* Modifications by Mark A. Williamson are (c) Intel Research Cambridge
*
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
* DEALINGS IN THE SOFTWARE.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/kernel.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <sys/bio.h>
#include <sys/bus.h>
#include <sys/conf.h>
#include <sys/module.h>
#include <sys/sysctl.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include <machine/resource.h>
#include <machine/intr_machdep.h>
#include <machine/vmparam.h>
#include <sys/bus_dma.h>
#include <machine/_inttypes.h>
#include <machine/xen/xen-os.h>
#include <machine/xen/xenvar.h>
#include <machine/xen/xenfunc.h>
#include <xen/hypervisor.h>
#include <xen/xen_intr.h>
#include <xen/evtchn.h>
#include <xen/gnttab.h>
#include <xen/interface/grant_table.h>
#include <xen/interface/io/protocols.h>
#include <xen/xenbus/xenbusvar.h>
#include <geom/geom_disk.h>
#include <dev/xen/blkfront/block.h>
#include "xenbus_if.h"
/* prototypes */
static void xb_free_command(struct xb_command *cm);
static void xb_startio(struct xb_softc *sc);
static void blkfront_connect(struct xb_softc *);
static void blkfront_closing(device_t);
static int blkfront_detach(device_t);
static int setup_blkring(struct xb_softc *);
static void blkif_int(void *);
static void blkfront_initialize(struct xb_softc *);
static int blkif_completion(struct xb_command *);
static void blkif_free(struct xb_softc *);
static void blkif_queue_cb(void *, bus_dma_segment_t *, int, int);
static MALLOC_DEFINE(M_XENBLOCKFRONT, "xbd", "Xen Block Front driver data");
#define GRANT_INVALID_REF 0
/* Control whether runtime update of vbds is enabled. */
#define ENABLE_VBD_UPDATE 0
#if ENABLE_VBD_UPDATE
static void vbd_update(void);
#endif
#define BLKIF_STATE_DISCONNECTED 0
#define BLKIF_STATE_CONNECTED 1
#define BLKIF_STATE_SUSPENDED 2
#ifdef notyet
static char *blkif_state_name[] = {
[BLKIF_STATE_DISCONNECTED] = "disconnected",
[BLKIF_STATE_CONNECTED] = "connected",
[BLKIF_STATE_SUSPENDED] = "closed",
};
static char * blkif_status_name[] = {
[BLKIF_INTERFACE_STATUS_CLOSED] = "closed",
[BLKIF_INTERFACE_STATUS_DISCONNECTED] = "disconnected",
[BLKIF_INTERFACE_STATUS_CONNECTED] = "connected",
[BLKIF_INTERFACE_STATUS_CHANGED] = "changed",
};
#endif
#if 0
#define DPRINTK(fmt, args...) printf("[XEN] %s:%d: " fmt ".\n", __func__, __LINE__, ##args)
#else
#define DPRINTK(fmt, args...)
#endif
static int blkif_open(struct disk *dp);
static int blkif_close(struct disk *dp);
static int blkif_ioctl(struct disk *dp, u_long cmd, void *addr, int flag, struct thread *td);
static int blkif_queue_request(struct xb_softc *sc, struct xb_command *cm);
static void xb_strategy(struct bio *bp);
// In order to quiesce the device during kernel dumps, outstanding requests to
// DOM0 for disk reads/writes need to be accounted for.
static int xb_dump(void *, void *, vm_offset_t, off_t, size_t);
/* XXX move to xb_vbd.c when VBD update support is added */
#define MAX_VBDS 64
#define XBD_SECTOR_SIZE 512 /* XXX: assume for now */
#define XBD_SECTOR_SHFT 9
/*
* Translate Linux major/minor to an appropriate name and unit
* number. For HVM guests, this allows us to use the same drive names
* with blkfront as the emulated drives, easing transition slightly.
*/
static void
blkfront_vdevice_to_unit(uint32_t vdevice, int *unit, const char **name)
{
static struct vdev_info {
int major;
int shift;
int base;
const char *name;
} info[] = {
{3, 6, 0, "ad"}, /* ide0 */
{22, 6, 2, "ad"}, /* ide1 */
{33, 6, 4, "ad"}, /* ide2 */
{34, 6, 6, "ad"}, /* ide3 */
{56, 6, 8, "ad"}, /* ide4 */
{57, 6, 10, "ad"}, /* ide5 */
{88, 6, 12, "ad"}, /* ide6 */
{89, 6, 14, "ad"}, /* ide7 */
{90, 6, 16, "ad"}, /* ide8 */
{91, 6, 18, "ad"}, /* ide9 */
{8, 4, 0, "da"}, /* scsi disk0 */
{65, 4, 16, "da"}, /* scsi disk1 */
{66, 4, 32, "da"}, /* scsi disk2 */
{67, 4, 48, "da"}, /* scsi disk3 */
{68, 4, 64, "da"}, /* scsi disk4 */
{69, 4, 80, "da"}, /* scsi disk5 */
{70, 4, 96, "da"}, /* scsi disk6 */
{71, 4, 112, "da"}, /* scsi disk7 */
{128, 4, 128, "da"}, /* scsi disk8 */
{129, 4, 144, "da"}, /* scsi disk9 */
{130, 4, 160, "da"}, /* scsi disk10 */
{131, 4, 176, "da"}, /* scsi disk11 */
{132, 4, 192, "da"}, /* scsi disk12 */
{133, 4, 208, "da"}, /* scsi disk13 */
{134, 4, 224, "da"}, /* scsi disk14 */
{135, 4, 240, "da"}, /* scsi disk15 */
{202, 4, 0, "xbd"}, /* xbd */
{0, 0, 0, NULL},
};
int major = vdevice >> 8;
int minor = vdevice & 0xff;
int i;
if (vdevice & (1 << 28)) {
*unit = (vdevice & ((1 << 28) - 1)) >> 8;
*name = "xbd";
return;
}
for (i = 0; info[i].major; i++) {
if (info[i].major == major) {
*unit = info[i].base + (minor >> info[i].shift);
*name = info[i].name;
return;
}
}
*unit = minor >> 4;
*name = "xbd";
}
int
xlvbd_add(struct xb_softc *sc, blkif_sector_t sectors,
int vdevice, uint16_t vdisk_info, unsigned long sector_size)
{
int unit, error = 0;
const char *name;
blkfront_vdevice_to_unit(vdevice, &unit, &name);
sc->xb_unit = unit;
if (strcmp(name, "xbd"))
device_printf(sc->xb_dev, "attaching as %s%d\n", name, unit);
sc->xb_disk = disk_alloc();
sc->xb_disk->d_unit = sc->xb_unit;
sc->xb_disk->d_open = blkif_open;
sc->xb_disk->d_close = blkif_close;
sc->xb_disk->d_ioctl = blkif_ioctl;
sc->xb_disk->d_strategy = xb_strategy;
sc->xb_disk->d_dump = xb_dump;
sc->xb_disk->d_name = name;
sc->xb_disk->d_drv1 = sc;
sc->xb_disk->d_sectorsize = sector_size;
sc->xb_disk->d_mediasize = sectors * sector_size;
sc->xb_disk->d_maxsize = sc->max_request_size;
sc->xb_disk->d_flags = 0;
disk_create(sc->xb_disk, DISK_VERSION);
return error;
}
/************************ end VBD support *****************/
/*
* Read/write routine for a buffer. Finds the proper unit, place it on
* the sortq and kick the controller.
*/
static void
xb_strategy(struct bio *bp)
{
struct xb_softc *sc = (struct xb_softc *)bp->bio_disk->d_drv1;
/* bogus disk? */
if (sc == NULL) {
bp->bio_error = EINVAL;
bp->bio_flags |= BIO_ERROR;
bp->bio_resid = bp->bio_bcount;
biodone(bp);
return;
}
/*
* Place it in the queue of disk activities for this disk
*/
mtx_lock(&sc->xb_io_lock);
xb_enqueue_bio(sc, bp);
xb_startio(sc);
mtx_unlock(&sc->xb_io_lock);
return;
}
static void
xb_bio_complete(struct xb_softc *sc, struct xb_command *cm)
{
struct bio *bp;
bp = cm->bp;
if ( unlikely(cm->status != BLKIF_RSP_OKAY) ) {
disk_err(bp, "disk error" , -1, 0);
printf(" status: %x\n", cm->status);
bp->bio_flags |= BIO_ERROR;
}
if (bp->bio_flags & BIO_ERROR)
bp->bio_error = EIO;
else
bp->bio_resid = 0;
xb_free_command(cm);
biodone(bp);
}
// Quiesce the disk writes for a dump file before allowing the next buffer.
static void
xb_quiesce(struct xb_softc *sc)
{
int mtd;
// While there are outstanding requests
while (!TAILQ_EMPTY(&sc->cm_busy)) {
RING_FINAL_CHECK_FOR_RESPONSES(&sc->ring, mtd);
if (mtd) {
/* Recieved request completions, update queue. */
blkif_int(sc);
}
if (!TAILQ_EMPTY(&sc->cm_busy)) {
/*
* Still pending requests, wait for the disk i/o
* to complete.
*/
HYPERVISOR_yield();
}
}
}
/* Kernel dump function for a paravirtualized disk device */
static void
xb_dump_complete(struct xb_command *cm)
{
xb_enqueue_complete(cm);
}
static int
xb_dump(void *arg, void *virtual, vm_offset_t physical, off_t offset,
size_t length)
{
struct disk *dp = arg;
struct xb_softc *sc = (struct xb_softc *) dp->d_drv1;
struct xb_command *cm;
size_t chunk;
int sbp;
int rc = 0;
if (length <= 0)
return (rc);
xb_quiesce(sc); /* All quiet on the western front. */
/*
* If this lock is held, then this module is failing, and a
* successful kernel dump is highly unlikely anyway.
*/
mtx_lock(&sc->xb_io_lock);
/* Split the 64KB block as needed */
for (sbp=0; length > 0; sbp++) {
cm = xb_dequeue_free(sc);
if (cm == NULL) {
mtx_unlock(&sc->xb_io_lock);
device_printf(sc->xb_dev, "dump: no more commands?\n");
return (EBUSY);
}
if (gnttab_alloc_grant_references(sc->max_request_segments,
&cm->gref_head) != 0) {
xb_free_command(cm);
mtx_unlock(&sc->xb_io_lock);
device_printf(sc->xb_dev, "no more grant allocs?\n");
return (EBUSY);
}
chunk = length > sc->max_request_size
? sc->max_request_size : length;
cm->data = virtual;
cm->datalen = chunk;
cm->operation = BLKIF_OP_WRITE;
cm->sector_number = offset / dp->d_sectorsize;
cm->cm_complete = xb_dump_complete;
xb_enqueue_ready(cm);
length -= chunk;
offset += chunk;
virtual = (char *) virtual + chunk;
}
/* Tell DOM0 to do the I/O */
xb_startio(sc);
mtx_unlock(&sc->xb_io_lock);
/* Poll for the completion. */
xb_quiesce(sc); /* All quite on the eastern front */
/* If there were any errors, bail out... */
while ((cm = xb_dequeue_complete(sc)) != NULL) {
if (cm->status != BLKIF_RSP_OKAY) {
device_printf(sc->xb_dev,
"Dump I/O failed at sector %jd\n",
cm->sector_number);
rc = EIO;
}
xb_free_command(cm);
}
return (rc);
}
static int
blkfront_probe(device_t dev)
{
if (!strcmp(xenbus_get_type(dev), "vbd")) {
device_set_desc(dev, "Virtual Block Device");
device_quiet(dev);
return (0);
}
return (ENXIO);
}
static void
xb_setup_sysctl(struct xb_softc *xb)
{
struct sysctl_ctx_list *sysctl_ctx = NULL;
struct sysctl_oid *sysctl_tree = NULL;
sysctl_ctx = device_get_sysctl_ctx(xb->xb_dev);
if (sysctl_ctx == NULL)
return;
sysctl_tree = device_get_sysctl_tree(xb->xb_dev);
if (sysctl_tree == NULL)
return;
SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
"max_requests", CTLFLAG_RD, &xb->max_requests, -1,
"maximum outstanding requests (negotiated)");
SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
"max_request_segments", CTLFLAG_RD,
&xb->max_request_segments, 0,
"maximum number of pages per requests (negotiated)");
SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
"max_request_size", CTLFLAG_RD,
&xb->max_request_size, 0,
"maximum size in bytes of a request (negotiated)");
SYSCTL_ADD_UINT(sysctl_ctx, SYSCTL_CHILDREN(sysctl_tree), OID_AUTO,
"ring_pages", CTLFLAG_RD,
&xb->ring_pages, 0,
"communication channel pages (negotiated)");
}
/*
* Setup supplies the backend dir, virtual device. We place an event
* channel and shared frame entries. We watch backend to wait if it's
* ok.
*/
static int
blkfront_attach(device_t dev)
{
struct xb_softc *sc;
const char *name;
uint32_t vdevice;
int error;
int i;
int unit;
/* FIXME: Use dynamic device id if this is not set. */
error = xs_scanf(XST_NIL, xenbus_get_node(dev),
"virtual-device", NULL, "%" PRIu32, &vdevice);
if (error) {
xenbus_dev_fatal(dev, error, "reading virtual-device");
device_printf(dev, "Couldn't determine virtual device.\n");
return (error);
}
blkfront_vdevice_to_unit(vdevice, &unit, &name);
if (!strcmp(name, "xbd"))
device_set_unit(dev, unit);
sc = device_get_softc(dev);
mtx_init(&sc->xb_io_lock, "blkfront i/o lock", NULL, MTX_DEF);
xb_initq_free(sc);
xb_initq_busy(sc);
xb_initq_ready(sc);
xb_initq_complete(sc);
xb_initq_bio(sc);
for (i = 0; i < XBF_MAX_RING_PAGES; i++)
sc->ring_ref[i] = GRANT_INVALID_REF;
sc->xb_dev = dev;
sc->vdevice = vdevice;
sc->connected = BLKIF_STATE_DISCONNECTED;
xb_setup_sysctl(sc);
/* Wait for backend device to publish its protocol capabilities. */
xenbus_set_state(dev, XenbusStateInitialising);
return (0);
}
static int
blkfront_suspend(device_t dev)
{
struct xb_softc *sc = device_get_softc(dev);
int retval;
int saved_state;
/* Prevent new requests being issued until we fix things up. */
mtx_lock(&sc->xb_io_lock);
saved_state = sc->connected;
sc->connected = BLKIF_STATE_SUSPENDED;
/* Wait for outstanding I/O to drain. */
retval = 0;
while (TAILQ_EMPTY(&sc->cm_busy) == 0) {
if (msleep(&sc->cm_busy, &sc->xb_io_lock,
PRIBIO, "blkf_susp", 30 * hz) == EWOULDBLOCK) {
retval = EBUSY;
break;
}
}
mtx_unlock(&sc->xb_io_lock);
if (retval != 0)
sc->connected = saved_state;
return (retval);
}
static int
blkfront_resume(device_t dev)
{
struct xb_softc *sc = device_get_softc(dev);
DPRINTK("blkfront_resume: %s\n", xenbus_get_node(dev));
blkif_free(sc);
blkfront_initialize(sc);
return (0);
}
static void
blkfront_initialize(struct xb_softc *sc)
{
const char *otherend_path;
const char *node_path;
uint32_t max_ring_page_order;
int error;
int i;
if (xenbus_get_state(sc->xb_dev) != XenbusStateInitialising) {
/* Initialization has already been performed. */
return;
}
/*
* Protocol defaults valid even if negotiation for a
* setting fails.
*/
max_ring_page_order = 0;
sc->ring_pages = 1;
sc->max_request_segments = BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK;
sc->max_request_size = XBF_SEGS_TO_SIZE(sc->max_request_segments);
sc->max_request_blocks = BLKIF_SEGS_TO_BLOCKS(sc->max_request_segments);
/*
* Protocol negotiation.
*
* \note xs_gather() returns on the first encountered error, so
* we must use independant calls in order to guarantee
* we don't miss information in a sparsly populated back-end
* tree.
*
* \note xs_scanf() does not update variables for unmatched
* fields.
*/
otherend_path = xenbus_get_otherend_path(sc->xb_dev);
node_path = xenbus_get_node(sc->xb_dev);
/* Support both backend schemes for relaying ring page limits. */
(void)xs_scanf(XST_NIL, otherend_path,
"max-ring-page-order", NULL, "%" PRIu32,
&max_ring_page_order);
sc->ring_pages = 1 << max_ring_page_order;
(void)xs_scanf(XST_NIL, otherend_path,
"max-ring-pages", NULL, "%" PRIu32,
&sc->ring_pages);
if (sc->ring_pages < 1)
sc->ring_pages = 1;
sc->max_requests = BLKIF_MAX_RING_REQUESTS(sc->ring_pages * PAGE_SIZE);
(void)xs_scanf(XST_NIL, otherend_path,
"max-requests", NULL, "%" PRIu32,
&sc->max_requests);
(void)xs_scanf(XST_NIL, otherend_path,
"max-request-segments", NULL, "%" PRIu32,
&sc->max_request_segments);
(void)xs_scanf(XST_NIL, otherend_path,
"max-request-size", NULL, "%" PRIu32,
&sc->max_request_size);
if (sc->ring_pages > XBF_MAX_RING_PAGES) {
device_printf(sc->xb_dev, "Back-end specified ring-pages of "
"%u limited to front-end limit of %zu.\n",
sc->ring_pages, XBF_MAX_RING_PAGES);
sc->ring_pages = XBF_MAX_RING_PAGES;
}
if (powerof2(sc->ring_pages) == 0) {
uint32_t new_page_limit;
new_page_limit = 0x01 << (fls(sc->ring_pages) - 1);
device_printf(sc->xb_dev, "Back-end specified ring-pages of "
"%u is not a power of 2. Limited to %u.\n",
sc->ring_pages, new_page_limit);
sc->ring_pages = new_page_limit;
}
if (sc->max_requests > XBF_MAX_REQUESTS) {
device_printf(sc->xb_dev, "Back-end specified max_requests of "
"%u limited to front-end limit of %u.\n",
sc->max_requests, XBF_MAX_REQUESTS);
sc->max_requests = XBF_MAX_REQUESTS;
}
if (sc->max_request_segments > XBF_MAX_SEGMENTS_PER_REQUEST) {
device_printf(sc->xb_dev, "Back-end specified "
"max_request_segments of %u limited to "
"front-end limit of %u.\n",
sc->max_request_segments,
XBF_MAX_SEGMENTS_PER_REQUEST);
sc->max_request_segments = XBF_MAX_SEGMENTS_PER_REQUEST;
}
if (sc->max_request_size > XBF_MAX_REQUEST_SIZE) {
device_printf(sc->xb_dev, "Back-end specified "
"max_request_size of %u limited to front-end "
"limit of %u.\n", sc->max_request_size,
XBF_MAX_REQUEST_SIZE);
sc->max_request_size = XBF_MAX_REQUEST_SIZE;
}
if (sc->max_request_size > XBF_SEGS_TO_SIZE(sc->max_request_segments)) {
device_printf(sc->xb_dev, "Back-end specified "
"max_request_size of %u limited to front-end "
"limit of %u. (Too few segments.)\n",
sc->max_request_size,
XBF_SEGS_TO_SIZE(sc->max_request_segments));
sc->max_request_size =
XBF_SEGS_TO_SIZE(sc->max_request_segments);
}
sc->max_request_blocks = BLKIF_SEGS_TO_BLOCKS(sc->max_request_segments);
/* Allocate datastructures based on negotiated values. */
error = bus_dma_tag_create(bus_get_dma_tag(sc->xb_dev), /* parent */
512, PAGE_SIZE, /* algnmnt, boundary */
BUS_SPACE_MAXADDR, /* lowaddr */
BUS_SPACE_MAXADDR, /* highaddr */
NULL, NULL, /* filter, filterarg */
sc->max_request_size,
sc->max_request_segments,
PAGE_SIZE, /* maxsegsize */
BUS_DMA_ALLOCNOW, /* flags */
busdma_lock_mutex, /* lockfunc */
&sc->xb_io_lock, /* lockarg */
&sc->xb_io_dmat);
if (error != 0) {
xenbus_dev_fatal(sc->xb_dev, error,
"Cannot allocate parent DMA tag\n");
return;
}
/* Per-transaction data allocation. */
sc->shadow = malloc(sizeof(*sc->shadow) * sc->max_requests,
M_XENBLOCKFRONT, M_NOWAIT|M_ZERO);
if (sc->shadow == NULL) {
bus_dma_tag_destroy(sc->xb_io_dmat);
xenbus_dev_fatal(sc->xb_dev, error,
"Cannot allocate request structures\n");
return;
}
for (i = 0; i < sc->max_requests; i++) {
struct xb_command *cm;
cm = &sc->shadow[i];
cm->sg_refs = malloc(sizeof(grant_ref_t)
* sc->max_request_segments,
M_XENBLOCKFRONT, M_NOWAIT);
if (cm->sg_refs == NULL)
break;
cm->id = i;
cm->cm_sc = sc;
if (bus_dmamap_create(sc->xb_io_dmat, 0, &cm->map) != 0)
break;
xb_free_command(cm);
}
if (setup_blkring(sc) != 0)
return;
/* Support both backend schemes for relaying ring page limits. */
if (sc->ring_pages > 1) {
error = xs_printf(XST_NIL, node_path,
"num-ring-pages","%u", sc->ring_pages);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"writing %s/num-ring-pages",
node_path);
return;
}
error = xs_printf(XST_NIL, node_path,
"ring-page-order", "%u",
fls(sc->ring_pages) - 1);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"writing %s/ring-page-order",
node_path);
return;
}
}
error = xs_printf(XST_NIL, node_path,
"max-requests","%u", sc->max_requests);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"writing %s/max-requests",
node_path);
return;
}
error = xs_printf(XST_NIL, node_path,
"max-request-segments","%u", sc->max_request_segments);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"writing %s/max-request-segments",
node_path);
return;
}
error = xs_printf(XST_NIL, node_path,
"max-request-size","%u", sc->max_request_size);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"writing %s/max-request-size",
node_path);
return;
}
error = xs_printf(XST_NIL, node_path, "event-channel",
"%u", irq_to_evtchn_port(sc->irq));
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"writing %s/event-channel",
node_path);
return;
}
error = xs_printf(XST_NIL, node_path,
"protocol", "%s", XEN_IO_PROTO_ABI_NATIVE);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"writing %s/protocol",
node_path);
return;
}
xenbus_set_state(sc->xb_dev, XenbusStateInitialised);
}
static int
setup_blkring(struct xb_softc *sc)
{
blkif_sring_t *sring;
uintptr_t sring_page_addr;
int error;
int i;
sring = malloc(sc->ring_pages * PAGE_SIZE, M_XENBLOCKFRONT,
M_NOWAIT|M_ZERO);
if (sring == NULL) {
xenbus_dev_fatal(sc->xb_dev, ENOMEM, "allocating shared ring");
return (ENOMEM);
}
SHARED_RING_INIT(sring);
FRONT_RING_INIT(&sc->ring, sring, sc->ring_pages * PAGE_SIZE);
for (i = 0, sring_page_addr = (uintptr_t)sring;
i < sc->ring_pages;
i++, sring_page_addr += PAGE_SIZE) {
error = xenbus_grant_ring(sc->xb_dev,
(vtomach(sring_page_addr) >> PAGE_SHIFT), &sc->ring_ref[i]);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"granting ring_ref(%d)", i);
return (error);
}
}
if (sc->ring_pages == 1) {
error = xs_printf(XST_NIL, xenbus_get_node(sc->xb_dev),
"ring-ref", "%u", sc->ring_ref[0]);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"writing %s/ring-ref",
xenbus_get_node(sc->xb_dev));
return (error);
}
} else {
for (i = 0; i < sc->ring_pages; i++) {
char ring_ref_name[]= "ring_refXX";
snprintf(ring_ref_name, sizeof(ring_ref_name),
"ring-ref%u", i);
error = xs_printf(XST_NIL, xenbus_get_node(sc->xb_dev),
ring_ref_name, "%u", sc->ring_ref[i]);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"writing %s/%s",
xenbus_get_node(sc->xb_dev),
ring_ref_name);
return (error);
}
}
}
error = bind_listening_port_to_irqhandler(
xenbus_get_otherend_id(sc->xb_dev),
"xbd", (driver_intr_t *)blkif_int, sc,
INTR_TYPE_BIO | INTR_MPSAFE, &sc->irq);
if (error) {
xenbus_dev_fatal(sc->xb_dev, error,
"bind_evtchn_to_irqhandler failed");
return (error);
}
return (0);
}
/**
* Callback received when the backend's state changes.
*/
static void
blkfront_backend_changed(device_t dev, XenbusState backend_state)
{
struct xb_softc *sc = device_get_softc(dev);
DPRINTK("backend_state=%d\n", backend_state);
switch (backend_state) {
case XenbusStateUnknown:
case XenbusStateInitialising:
case XenbusStateReconfigured:
case XenbusStateReconfiguring:
case XenbusStateClosed:
break;
case XenbusStateInitWait:
case XenbusStateInitialised:
blkfront_initialize(sc);
break;
case XenbusStateConnected:
blkfront_initialize(sc);
blkfront_connect(sc);
break;
case XenbusStateClosing:
if (sc->users > 0)
xenbus_dev_error(dev, -EBUSY,
"Device in use; refusing to close");
else
blkfront_closing(dev);
break;
}
}
/*
** Invoked when the backend is finally 'ready' (and has published
** the details about the physical device - #sectors, size, etc).
*/
static void
blkfront_connect(struct xb_softc *sc)
{
device_t dev = sc->xb_dev;
unsigned long sectors, sector_size;
unsigned int binfo;
int err, feature_barrier;
if( (sc->connected == BLKIF_STATE_CONNECTED) ||
(sc->connected == BLKIF_STATE_SUSPENDED) )
return;
DPRINTK("blkfront.c:connect:%s.\n", xenbus_get_otherend_path(dev));
err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
"sectors", "%lu", &sectors,
"info", "%u", &binfo,
"sector-size", "%lu", &sector_size,
NULL);
if (err) {
xenbus_dev_fatal(dev, err,
"reading backend fields at %s",
xenbus_get_otherend_path(dev));
return;
}
err = xs_gather(XST_NIL, xenbus_get_otherend_path(dev),
"feature-barrier", "%lu", &feature_barrier,
NULL);
if (!err || feature_barrier)
sc->xb_flags |= XB_BARRIER;
if (sc->xb_disk == NULL) {
device_printf(dev, "%juMB <%s> at %s",
(uintmax_t) sectors / (1048576 / sector_size),
device_get_desc(dev),
xenbus_get_node(dev));
bus_print_child_footer(device_get_parent(dev), dev);
xlvbd_add(sc, sectors, sc->vdevice, binfo, sector_size);
}
(void)xenbus_set_state(dev, XenbusStateConnected);
/* Kick pending requests. */
mtx_lock(&sc->xb_io_lock);
sc->connected = BLKIF_STATE_CONNECTED;
xb_startio(sc);
sc->xb_flags |= XB_READY;
mtx_unlock(&sc->xb_io_lock);
}
/**
* Handle the change of state of the backend to Closing. We must delete our
* device-layer structures now, to ensure that writes are flushed through to
* the backend. Once this is done, we can switch to Closed in
* acknowledgement.
*/
static void
blkfront_closing(device_t dev)
{
struct xb_softc *sc = device_get_softc(dev);
xenbus_set_state(dev, XenbusStateClosing);
DPRINTK("blkfront_closing: %s removed\n", xenbus_get_node(dev));
if (sc->xb_disk != NULL) {
disk_destroy(sc->xb_disk);
sc->xb_disk = NULL;
}
xenbus_set_state(dev, XenbusStateClosed);
}
static int
blkfront_detach(device_t dev)
{
struct xb_softc *sc = device_get_softc(dev);
DPRINTK("blkfront_remove: %s removed\n", xenbus_get_node(dev));
blkif_free(sc);
mtx_destroy(&sc->xb_io_lock);
return 0;
}
static inline void
flush_requests(struct xb_softc *sc)
{
int notify;
RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&sc->ring, notify);
if (notify)
notify_remote_via_irq(sc->irq);
}
static void
blkif_restart_queue_callback(void *arg)
{
struct xb_softc *sc = arg;
mtx_lock(&sc->xb_io_lock);
xb_startio(sc);
mtx_unlock(&sc->xb_io_lock);
}
static int
blkif_open(struct disk *dp)
{
struct xb_softc *sc = (struct xb_softc *)dp->d_drv1;
if (sc == NULL) {
printf("xb%d: not found", sc->xb_unit);
return (ENXIO);
}
sc->xb_flags |= XB_OPEN;
sc->users++;
return (0);
}
static int
blkif_close(struct disk *dp)
{
struct xb_softc *sc = (struct xb_softc *)dp->d_drv1;
if (sc == NULL)
return (ENXIO);
sc->xb_flags &= ~XB_OPEN;
if (--(sc->users) == 0) {
/*
* Check whether we have been instructed to close. We will
* have ignored this request initially, as the device was
* still mounted.
*/
if (xenbus_get_otherend_state(sc->xb_dev) == XenbusStateClosing)
blkfront_closing(sc->xb_dev);
}
return (0);
}
static int
blkif_ioctl(struct disk *dp, u_long cmd, void *addr, int flag, struct thread *td)
{
struct xb_softc *sc = (struct xb_softc *)dp->d_drv1;
if (sc == NULL)
return (ENXIO);
return (ENOTTY);
}
static void
xb_free_command(struct xb_command *cm)
{
KASSERT((cm->cm_flags & XB_ON_XBQ_MASK) == 0,
("Freeing command that is still on a queue\n"));
cm->cm_flags = 0;
cm->bp = NULL;
cm->cm_complete = NULL;
xb_enqueue_free(cm);
}
/*
* blkif_queue_request
*
* request block io
*
* id: for guest use only.
* operation: BLKIF_OP_{READ,WRITE,PROBE}
* buffer: buffer to read/write into. this should be a
* virtual address in the guest os.
*/
static struct xb_command *
xb_bio_command(struct xb_softc *sc)
{
struct xb_command *cm;
struct bio *bp;
if (unlikely(sc->connected != BLKIF_STATE_CONNECTED))
return (NULL);
bp = xb_dequeue_bio(sc);
if (bp == NULL)
return (NULL);
if ((cm = xb_dequeue_free(sc)) == NULL) {
xb_requeue_bio(sc, bp);
return (NULL);
}
if (gnttab_alloc_grant_references(sc->max_request_segments,
&cm->gref_head) != 0) {
gnttab_request_free_callback(&sc->callback,
blkif_restart_queue_callback, sc,
sc->max_request_segments);
xb_requeue_bio(sc, bp);
xb_enqueue_free(cm);
sc->xb_flags |= XB_FROZEN;
return (NULL);
}
cm->bp = bp;
cm->data = bp->bio_data;
cm->datalen = bp->bio_bcount;
cm->operation = (bp->bio_cmd == BIO_READ) ? BLKIF_OP_READ :
BLKIF_OP_WRITE;
cm->sector_number = (blkif_sector_t)bp->bio_pblkno;
return (cm);
}
static int
blkif_queue_request(struct xb_softc *sc, struct xb_command *cm)
{
int error;
error = bus_dmamap_load(sc->xb_io_dmat, cm->map, cm->data, cm->datalen,
blkif_queue_cb, cm, 0);
if (error == EINPROGRESS) {
printf("EINPROGRESS\n");
sc->xb_flags |= XB_FROZEN;
cm->cm_flags |= XB_CMD_FROZEN;
return (0);
}
return (error);
}
static void
blkif_queue_cb(void *arg, bus_dma_segment_t *segs, int nsegs, int error)
{
struct xb_softc *sc;
struct xb_command *cm;
blkif_request_t *ring_req;
struct blkif_request_segment *sg;
struct blkif_request_segment *last_block_sg;
grant_ref_t *sg_ref;
vm_paddr_t buffer_ma;
uint64_t fsect, lsect;
int ref;
int op;
int block_segs;
cm = arg;
sc = cm->cm_sc;
//printf("%s: Start\n", __func__);
if (error) {
printf("error %d in blkif_queue_cb\n", error);
cm->bp->bio_error = EIO;
biodone(cm->bp);
xb_free_command(cm);
return;
}
/* Fill out a communications ring structure. */
ring_req = RING_GET_REQUEST(&sc->ring, sc->ring.req_prod_pvt);
sc->ring.req_prod_pvt++;
ring_req->id = cm->id;
ring_req->operation = cm->operation;
ring_req->sector_number = cm->sector_number;
ring_req->handle = (blkif_vdev_t)(uintptr_t)sc->xb_disk;
ring_req->nr_segments = nsegs;
cm->nseg = nsegs;
block_segs = MIN(nsegs, BLKIF_MAX_SEGMENTS_PER_HEADER_BLOCK);
sg = ring_req->seg;
last_block_sg = sg + block_segs;
sg_ref = cm->sg_refs;
while (1) {
while (sg < last_block_sg) {
buffer_ma = segs->ds_addr;
fsect = (buffer_ma & PAGE_MASK) >> XBD_SECTOR_SHFT;
lsect = fsect + (segs->ds_len >> XBD_SECTOR_SHFT) - 1;
KASSERT(lsect <= 7, ("XEN disk driver data cannot "
"cross a page boundary"));
/* install a grant reference. */
ref = gnttab_claim_grant_reference(&cm->gref_head);
/*
* GNTTAB_LIST_END == 0xffffffff, but it is private
* to gnttab.c.
*/
KASSERT(ref != ~0, ("grant_reference failed"));
gnttab_grant_foreign_access_ref(
ref,
xenbus_get_otherend_id(sc->xb_dev),
buffer_ma >> PAGE_SHIFT,
ring_req->operation == BLKIF_OP_WRITE);
*sg_ref = ref;
*sg = (struct blkif_request_segment) {
.gref = ref,
.first_sect = fsect,
.last_sect = lsect };
sg++;
sg_ref++;
segs++;
nsegs--;
}
block_segs = MIN(nsegs, BLKIF_MAX_SEGMENTS_PER_SEGMENT_BLOCK);
if (block_segs == 0)
break;
sg = BLKRING_GET_SEG_BLOCK(&sc->ring, sc->ring.req_prod_pvt);
sc->ring.req_prod_pvt++;
last_block_sg = sg + block_segs;
}
if (cm->operation == BLKIF_OP_READ)
op = BUS_DMASYNC_PREREAD;
else if (cm->operation == BLKIF_OP_WRITE)
op = BUS_DMASYNC_PREWRITE;
else
op = 0;
bus_dmamap_sync(sc->xb_io_dmat, cm->map, op);
gnttab_free_grant_references(cm->gref_head);
xb_enqueue_busy(cm);
/*
* This flag means that we're probably executing in the busdma swi
* instead of in the startio context, so an explicit flush is needed.
*/
if (cm->cm_flags & XB_CMD_FROZEN)
flush_requests(sc);
//printf("%s: Done\n", __func__);
return;
}
/*
* Dequeue buffers and place them in the shared communication ring.
* Return when no more requests can be accepted or all buffers have
* been queued.
*
* Signal XEN once the ring has been filled out.
*/
static void
xb_startio(struct xb_softc *sc)
{
struct xb_command *cm;
int error, queued = 0;
mtx_assert(&sc->xb_io_lock, MA_OWNED);
if (sc->connected != BLKIF_STATE_CONNECTED)
return;
while (RING_FREE_REQUESTS(&sc->ring) >= sc->max_request_blocks) {
if (sc->xb_flags & XB_FROZEN)
break;
cm = xb_dequeue_ready(sc);
if (cm == NULL)
cm = xb_bio_command(sc);
if (cm == NULL)
break;
if ((error = blkif_queue_request(sc, cm)) != 0) {
printf("blkif_queue_request returned %d\n", error);
break;
}
queued++;
}
if (queued != 0)
flush_requests(sc);
}
static void
blkif_int(void *xsc)
{
struct xb_softc *sc = xsc;
struct xb_command *cm;
blkif_response_t *bret;
RING_IDX i, rp;
int op;
mtx_lock(&sc->xb_io_lock);
if (unlikely(sc->connected == BLKIF_STATE_DISCONNECTED)) {
mtx_unlock(&sc->xb_io_lock);
return;
}
again:
rp = sc->ring.sring->rsp_prod;
rmb(); /* Ensure we see queued responses up to 'rp'. */
for (i = sc->ring.rsp_cons; i != rp;) {
bret = RING_GET_RESPONSE(&sc->ring, i);
cm = &sc->shadow[bret->id];
xb_remove_busy(cm);
i += blkif_completion(cm);
if (cm->operation == BLKIF_OP_READ)
op = BUS_DMASYNC_POSTREAD;
else if (cm->operation == BLKIF_OP_WRITE)
op = BUS_DMASYNC_POSTWRITE;
else
op = 0;
bus_dmamap_sync(sc->xb_io_dmat, cm->map, op);
bus_dmamap_unload(sc->xb_io_dmat, cm->map);
/*
* If commands are completing then resources are probably
* being freed as well. It's a cheap assumption even when
* wrong.
*/
sc->xb_flags &= ~XB_FROZEN;
/*
* Directly call the i/o complete routine to save an
* an indirection in the common case.
*/
cm->status = bret->status;
if (cm->bp)
xb_bio_complete(sc, cm);
else if (cm->cm_complete)
(cm->cm_complete)(cm);
else
xb_free_command(cm);
}
sc->ring.rsp_cons = i;
if (i != sc->ring.req_prod_pvt) {
int more_to_do;
RING_FINAL_CHECK_FOR_RESPONSES(&sc->ring, more_to_do);
if (more_to_do)
goto again;
} else {
sc->ring.sring->rsp_event = i + 1;
}
xb_startio(sc);
if (unlikely(sc->connected == BLKIF_STATE_SUSPENDED))
wakeup(&sc->cm_busy);
mtx_unlock(&sc->xb_io_lock);
}
static void
blkif_free(struct xb_softc *sc)
{
uint8_t *sring_page_ptr;
int i;
/* Prevent new requests being issued until we fix things up. */
mtx_lock(&sc->xb_io_lock);
sc->connected = BLKIF_STATE_DISCONNECTED;
mtx_unlock(&sc->xb_io_lock);
/* Free resources associated with old device channel. */
if (sc->ring.sring != NULL) {
sring_page_ptr = (uint8_t *)sc->ring.sring;
for (i = 0; i < sc->ring_pages; i++) {
if (sc->ring_ref[i] != GRANT_INVALID_REF) {
gnttab_end_foreign_access_ref(sc->ring_ref[i]);
sc->ring_ref[i] = GRANT_INVALID_REF;
}
sring_page_ptr += PAGE_SIZE;
}
free(sc->ring.sring, M_XENBLOCKFRONT);
sc->ring.sring = NULL;
}
if (sc->shadow) {
for (i = 0; i < sc->max_requests; i++) {
struct xb_command *cm;
cm = &sc->shadow[i];
if (cm->sg_refs != NULL) {
free(cm->sg_refs, M_XENBLOCKFRONT);
cm->sg_refs = NULL;
}
bus_dmamap_destroy(sc->xb_io_dmat, cm->map);
}
free(sc->shadow, M_XENBLOCKFRONT);
sc->shadow = NULL;
bus_dma_tag_destroy(sc->xb_io_dmat);
xb_initq_free(sc);
xb_initq_ready(sc);
xb_initq_complete(sc);
}
if (sc->irq) {
unbind_from_irqhandler(sc->irq);
sc->irq = 0;
}
}
static int
blkif_completion(struct xb_command *s)
{
//printf("%s: Req %p(%d)\n", __func__, s, s->nseg);
gnttab_end_foreign_access_references(s->nseg, s->sg_refs);
return (BLKIF_SEGS_TO_BLOCKS(s->nseg));
}
/* ** Driver registration ** */
static device_method_t blkfront_methods[] = {
/* Device interface */
DEVMETHOD(device_probe, blkfront_probe),
DEVMETHOD(device_attach, blkfront_attach),
DEVMETHOD(device_detach, blkfront_detach),
DEVMETHOD(device_shutdown, bus_generic_shutdown),
DEVMETHOD(device_suspend, blkfront_suspend),
DEVMETHOD(device_resume, blkfront_resume),
/* Xenbus interface */
DEVMETHOD(xenbus_otherend_changed, blkfront_backend_changed),
{ 0, 0 }
};
static driver_t blkfront_driver = {
"xbd",
blkfront_methods,
sizeof(struct xb_softc),
};
devclass_t blkfront_devclass;
DRIVER_MODULE(xbd, xenbusb_front, blkfront_driver, blkfront_devclass, 0, 0);
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