ref: 82c08a8a4469c4b4ba515d74addc7aac747a17d9
dir: /sys/src/9/xen/sdxen.c/
/*
* Xen block storage device frontend
*
* The present implementation follows the principle of
* "what's the simplest thing that could possibly work?".
* We can think about performance later.
* We can think about dynamically attaching and removing devices later.
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#include "ureg.h"
#include "../port/error.h"
#include "../port/sd.h"
#define LOG(a)
/*
* conversions to machine page numbers, pages and addresses
*/
#define MFN(pa) (patomfn[(pa)>>PGSHIFT])
#define MFNPG(pa) (MFN(pa)<<PGSHIFT)
#define PA2MA(pa) (MFNPG(pa) | PGOFF(pa))
#define VA2MA(va) PA2MA(PADDR(va))
#define VA2MFN(va) MFN(PADDR(va))
enum {
Ndevs = 4,
MajorDevSD = 0x800,
MajorDevHDA = 0x300,
MajorDevHDC = 0x1600,
MajorDevXVD = 0xCA00,
};
extern SDifc sdxenifc;
typedef struct Ctlr Ctlr;
struct Ctlr {
int online;
ulong secsize;
ulong sectors;
int backend;
int devid;
int evtchn;
blkif_front_ring_t ring;
int ringref;
Lock ringlock;
char *frame;
QLock iolock;
int iodone;
Rendez wiodone;
};
static int
ringinit(Ctlr *ctlr, char *a)
{
blkif_sring_t *sr;
sr = (blkif_sring_t*)a;
memset(sr, 0, BY2PG);
SHARED_RING_INIT(sr);
FRONT_RING_INIT(&ctlr->ring, sr, BY2PG);
ctlr->ringref = shareframe(ctlr->backend, sr, 1);
return BY2PG;
}
static int
vbdsend(Ctlr *ctlr, int write, int ref, int nb, uvlong bno)
{
blkif_request_t *req;
int i, notify;
ilock(&ctlr->ringlock); // XXX conservative
i = ctlr->ring.req_prod_pvt;
req = RING_GET_REQUEST(&ctlr->ring, i); // XXX overflow?
req->operation = write ? BLKIF_OP_WRITE : BLKIF_OP_READ;
req->nr_segments = 1;
req->handle = ctlr->devid;
req->id = 1;
req->sector_number = bno;
req->seg[0].gref = ref;
req->seg[0].first_sect = 0;
req->seg[0].last_sect = nb-1;
ctlr->ring.req_prod_pvt = i+1;
RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&ctlr->ring, notify);
iunlock(&ctlr->ringlock);
return notify;
}
static void
backendconnect(Ctlr *ctlr)
{
char dir[64];
char buf[64];
sprint(dir, "device/vbd/%d/", ctlr->devid);
xenstore_setd(dir, "ring-ref", ctlr->ringref);
xenstore_setd(dir, "event-channel", ctlr->evtchn);
xenstore_setd(dir, "state", XenbusStateInitialised);
xenstore_gets(dir, "backend", buf, sizeof buf);
sprint(dir, "%s/", buf);
HYPERVISOR_yield();
xenstore_gets(dir, "state", buf, sizeof buf);
while (strtol(buf, 0, 0) != XenbusStateConnected) {
print("sdxen: waiting for vbd %d to connect\n", ctlr->devid);
tsleep(&up->sleep, return0, 0, 50);
xenstore_gets(dir, "state", buf, sizeof buf);
}
xenstore_gets(dir, "sector-size", buf, sizeof buf);
ctlr->secsize = strtol(buf, 0, 0);
xenstore_gets(dir, "sectors", buf, sizeof buf);
ctlr->sectors = strtol(buf, 0, 0);
print("sdxen: backend %s secsize %ld sectors %ld\n", dir, ctlr->secsize, ctlr->sectors);
if (ctlr->secsize > BY2PG)
panic("sdxen: sector size bigger than mmu page size");
}
static void
backendactivate(Ctlr *ctlr)
{
char dir[64];
sprint(dir, "device/vbd/%d/", ctlr->devid);
xenstore_setd(dir, "state", XenbusStateConnected);
}
static SDev*
xenpnp(void)
{
SDev *sdev[Ndevs];
static char idno[Ndevs] = { '0', 'C', 'D', 'E' };
static char nunit[Ndevs] = { 8, 2, 2, 8 };
int i;
for (i = 0; i < Ndevs; i++) {
sdev[i] = mallocz(sizeof(SDev), 1);
sdev[i]->ifc = &sdxenifc;
sdev[i]->idno = idno[i];
sdev[i]->nunit = nunit[i];
sdev[i]->ctlr = (Ctlr**)mallocz(sdev[i]->nunit*sizeof(Ctlr*), 1);
if (i > 0)
sdev[i]->next = sdev[i-1];
}
return sdev[Ndevs-1];
}
static int
linuxdev(int idno, int subno)
{
switch (idno) {
case '0':
return MajorDevSD + 16*subno;
case 'C':
return MajorDevHDA + 64*subno;
case 'D':
return MajorDevHDC + 64*subno;
case 'E':
return MajorDevXVD + 16*subno;
default:
return 0;
}
}
static int
xenverify(SDunit *unit)
{
Ctlr *ctlr;
char dir[64];
char buf[64];
int devid;
int npage;
char *p;
if (unit->subno > unit->dev->nunit)
return 0;
devid = linuxdev(unit->dev->idno, unit->subno);
sprint(dir, "device/vbd/%d/", devid);
if (xenstore_gets(dir, "backend-id", buf, sizeof buf) <= 0)
return 0;
ctlr = mallocz(sizeof(Ctlr), 1);
((Ctlr**)unit->dev->ctlr)[unit->subno] = ctlr;
ctlr->devid = devid;
ctlr->backend = strtol(buf, 0, 0);
npage = 2;
p = xspanalloc(npage<<PGSHIFT, BY2PG, 0);
p += ringinit(ctlr, p);
ctlr->frame = p;
ctlr->evtchn = xenchanalloc(ctlr->backend);
backendconnect(ctlr);
unit->inquiry[0] = 0; // XXX how do we know if it's a CD?
unit->inquiry[2] = 2;
unit->inquiry[3] = 2;
unit->inquiry[4] = sizeof(unit->inquiry)-4;
strcpy((char*)&unit->inquiry[8], "Xen block device");
return 1;
}
static int
wiodone(void *a)
{
return ((Ctlr*)a)->iodone != 0;
}
static void
sdxenintr(Ureg *, void *a)
{
Ctlr *ctlr = a;
blkif_response_t *rsp;
int i, avail;
ilock(&ctlr->ringlock); // XXX conservative
for (;;) {
RING_FINAL_CHECK_FOR_RESPONSES(&ctlr->ring, avail);
if (!avail)
break;
i = ctlr->ring.rsp_cons;
rsp = RING_GET_RESPONSE(&ctlr->ring, i);
LOG(dprint("sdxen rsp %llud %d %d\n", rsp->id, rsp->operation, rsp->status);)
if (rsp->status == BLKIF_RSP_OKAY)
ctlr->iodone = 1;
else
ctlr->iodone = -1;
ctlr->ring.rsp_cons = ++i;
}
iunlock(&ctlr->ringlock);
if (ctlr->iodone)
wakeup(&ctlr->wiodone);
}
static Ctlr *kickctlr;
static void
kickme(void)
{
Ctlr *ctlr = kickctlr;
shared_info_t *s;
if (ctlr) {
s = HYPERVISOR_shared_info;
dprint("tick %d %d prod %d cons %d pending %x mask %x\n",
m->ticks, ctlr->iodone, ctlr->ring.sring->rsp_prod, ctlr->ring.rsp_cons,
s->evtchn_pending[0], s->evtchn_mask[0]);
sdxenintr(0, ctlr);
}
}
static int
xenonline(SDunit *unit)
{
Ctlr *ctlr;
ctlr = ((Ctlr**)unit->dev->ctlr)[unit->subno];
unit->sectors = ctlr->sectors;
unit->secsize = ctlr->secsize;
if (ctlr->online == 0) {
intrenable(ctlr->evtchn, sdxenintr, ctlr, BUSUNKNOWN, "vbd");
//kickctlr = ctlr;
//addclock0link(kickme, 10000);
backendactivate(ctlr);
ctlr->online = 1;
}
return 1;
}
static int
xenrio(SDreq*)
{
return -1;
}
static long
xenbio(SDunit* unit, int lun, int write, void* data, long nb, uvlong bno)
{
Ctlr *ctlr;
char *buf;
long bcount, len;
int ref;
int n;
USED(lun); // XXX meaningless
ctlr = ((Ctlr**)unit->dev->ctlr)[unit->subno];
LOG(("xenbio %c %lux %ld %lld\n", write? 'w' : 'r', (ulong)data, nb, bno);)
buf = data;
// XXX extra copying & fragmentation could be avoided by
// redefining sdmalloc() to get page-aligned buffers
if ((ulong)data&(BY2PG-1))
buf = ctlr->frame;
bcount = BY2PG/unit->secsize;
qlock(&ctlr->iolock);
for (n = nb; n > 0; n -= bcount) {
ref = shareframe(ctlr->backend, buf, !write);
if (bcount > n)
bcount = n;
len = bcount*unit->secsize;
if (write && buf == ctlr->frame)
memmove(buf, data, len);
ctlr->iodone = 0;
if (vbdsend(ctlr, write, ref, bcount, bno))
xenchannotify(ctlr->evtchn);
LOG(dprint("sleeping %d prod %d cons %d pending %x mask %x \n", ctlr->iodone, ctlr->ring.sring->rsp_prod, ctlr->ring.rsp_cons,
HYPERVISOR_shared_info->evtchn_pending[0], HYPERVISOR_shared_info->evtchn_mask[0]);)
sleep(&ctlr->wiodone, wiodone, ctlr);
xengrantend(ref);
if (ctlr->iodone < 0) {
qunlock(&ctlr->iolock);
return -1;
}
if (buf == ctlr->frame) {
if (!write)
memmove(data, buf, len);
data = (char*)data + len;
} else
buf += len;
bno += bcount;
}
qunlock(&ctlr->iolock);
return (nb-n)*unit->secsize;
}
static void
xenclear(SDev *)
{
}
SDifc sdxenifc = {
"xen", /* name */
xenpnp, /* pnp */
0, /* legacy */
0, /* enable */
0, /* disable */
xenverify, /* verify */
xenonline, /* online */
xenrio, /* rio */
0, /* rctl */
0, /* wctl */
xenbio, /* bio */
0, /* probe */
xenclear, /* clear */
0, /* stat */
};