From: Anastasiia Lukianenko anastasiia_lukianenko@epam.com
Implement Xen para-virtual frontend to backend communication and actually read/write disk data.
This is based on mini-os implementation of the para-virtual block frontend driver.
Signed-off-by: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com Signed-off-by: Anastasiia Lukianenko anastasiia_lukianenko@epam.com --- drivers/xen/events.c | 2 +- drivers/xen/pvblock.c | 311 ++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 301 insertions(+), 12 deletions(-)
diff --git a/drivers/xen/events.c b/drivers/xen/events.c index a1b36a2196..192b290c02 100644 --- a/drivers/xen/events.c +++ b/drivers/xen/events.c @@ -104,7 +104,7 @@ void unbind_evtchn(evtchn_port_t port) int rc;
if (ev_actions[port].handler == default_handler) - printf("WARN: No handler for port %d when unbinding\n", port); + debug("Default handler for port %d when unbinding\n", port); mask_evtchn(port); clear_evtchn(port);
diff --git a/drivers/xen/pvblock.c b/drivers/xen/pvblock.c index 9ed18be633..a23afc2cb2 100644 --- a/drivers/xen/pvblock.c +++ b/drivers/xen/pvblock.c @@ -15,6 +15,7 @@ #include <asm/io.h> #include <asm/xen/system.h>
+#include <linux/bug.h> #include <linux/compat.h>
#include <xen/events.h> @@ -31,6 +32,7 @@
#define O_RDONLY 00 #define O_RDWR 02 +#define WAIT_RING_TO_MS 10
struct blkfront_info { u64 sectors; @@ -53,12 +55,30 @@ struct blkfront_dev { char *backend; struct blkfront_info info; unsigned int devid; + u8 *bounce_buffer; };
struct blkfront_platdata { unsigned int devid; };
+struct blkfront_aiocb { + struct blkfront_dev *aio_dev; + u8 *aio_buf; + size_t aio_nbytes; + off_t aio_offset; + size_t total_bytes; + u8 is_write; + void *data; + + grant_ref_t gref[BLKIF_MAX_SEGMENTS_PER_REQUEST]; + int n; + + void (*aio_cb)(struct blkfront_aiocb *aiocb, int ret); +}; + +static void blkfront_sync(struct blkfront_dev *dev); + static void free_blkfront(struct blkfront_dev *dev) { mask_evtchn(dev->evtchn); @@ -69,16 +89,11 @@ static void free_blkfront(struct blkfront_dev *dev)
unbind_evtchn(dev->evtchn);
+ free(dev->bounce_buffer); free(dev->nodename); free(dev); }
-static void blkfront_handler(evtchn_port_t port, struct pt_regs *regs, - void *data) -{ - printf("%s [Port %d] - event received\n", __func__, port); -} - static int init_blkfront(unsigned int devid, struct blkfront_dev *dev) { xenbus_transaction_t xbt; @@ -99,7 +114,7 @@ static int init_blkfront(unsigned int devid, struct blkfront_dev *dev)
snprintf(path, sizeof(path), "%s/backend-id", nodename); dev->dom = xenbus_read_integer(path); - evtchn_alloc_unbound(dev->dom, blkfront_handler, dev, &dev->evtchn); + evtchn_alloc_unbound(dev->dom, NULL, dev, &dev->evtchn);
s = (struct blkif_sring *)memalign(PAGE_SIZE, PAGE_SIZE); if (!s) { @@ -220,8 +235,16 @@ done: } unmask_evtchn(dev->evtchn);
- debug("%llu sectors of %u bytes\n", - dev->info.sectors, dev->info.sector_size); + dev->bounce_buffer = memalign(dev->info.sector_size, + dev->info.sector_size); + if (!dev->bounce_buffer) { + printf("Failed to allocate bouncing buffer\n"); + goto error; + } + + debug("%llu sectors of %u bytes, bounce buffer at %p\n", + dev->info.sectors, dev->info.sector_size, + dev->bounce_buffer);
return 0;
@@ -242,6 +265,8 @@ static void shutdown_blkfront(struct blkfront_dev *dev)
debug("Close " DRV_NAME ", device ID %d\n", dev->devid);
+ blkfront_sync(dev); + snprintf(path, sizeof(path), "%s/state", dev->backend); snprintf(nodename, sizeof(nodename), "%s/state", dev->nodename);
@@ -296,16 +321,280 @@ close: free_blkfront(dev); }
+static int blkfront_aio_poll(struct blkfront_dev *dev) +{ + RING_IDX rp, cons; + struct blkif_response *rsp; + int more; + int nr_consumed; + +moretodo: + rp = dev->ring.sring->rsp_prod; + rmb(); /* Ensure we see queued responses up to 'rp'. */ + cons = dev->ring.rsp_cons; + + nr_consumed = 0; + while ((cons != rp)) { + struct blkfront_aiocb *aiocbp; + int status; + + rsp = RING_GET_RESPONSE(&dev->ring, cons); + nr_consumed++; + + aiocbp = (void *)(uintptr_t)rsp->id; + status = rsp->status; + + switch (rsp->operation) { + case BLKIF_OP_READ: + case BLKIF_OP_WRITE: + { + int j; + + if (status != BLKIF_RSP_OKAY) + printf("%s error %d on %s at offset %llu, num bytes %llu\n", + rsp->operation == BLKIF_OP_READ ? + "read" : "write", + status, aiocbp->aio_dev->nodename, + (unsigned long long)aiocbp->aio_offset, + (unsigned long long)aiocbp->aio_nbytes); + + for (j = 0; j < aiocbp->n; j++) + gnttab_end_access(aiocbp->gref[j]); + + break; + } + + case BLKIF_OP_WRITE_BARRIER: + if (status != BLKIF_RSP_OKAY) + printf("write barrier error %d\n", status); + break; + case BLKIF_OP_FLUSH_DISKCACHE: + if (status != BLKIF_RSP_OKAY) + printf("flush error %d\n", status); + break; + + default: + printf("unrecognized block operation %d response (status %d)\n", + rsp->operation, status); + break; + } + + dev->ring.rsp_cons = ++cons; + /* Nota: callback frees aiocbp itself */ + if (aiocbp && aiocbp->aio_cb) + aiocbp->aio_cb(aiocbp, status ? -EIO : 0); + if (dev->ring.rsp_cons != cons) + /* We reentered, we must not continue here */ + break; + } + + RING_FINAL_CHECK_FOR_RESPONSES(&dev->ring, more); + if (more) + goto moretodo; + + return nr_consumed; +} + +static void blkfront_wait_slot(struct blkfront_dev *dev) +{ + /* Wait for a slot */ + if (RING_FULL(&dev->ring)) { + while (true) { + blkfront_aio_poll(dev); + if (!RING_FULL(&dev->ring)) + break; + wait_event_timeout(NULL, !RING_FULL(&dev->ring), + WAIT_RING_TO_MS); + } + } +} + +/* Issue an aio */ +static void blkfront_aio(struct blkfront_aiocb *aiocbp, int write) +{ + struct blkfront_dev *dev = aiocbp->aio_dev; + struct blkif_request *req; + RING_IDX i; + int notify; + int n, j; + uintptr_t start, end; + + /* Can't io at non-sector-aligned location */ + BUG_ON(aiocbp->aio_offset & (dev->info.sector_size - 1)); + /* Can't io non-sector-sized amounts */ + BUG_ON(aiocbp->aio_nbytes & (dev->info.sector_size - 1)); + /* Can't io non-sector-aligned buffer */ + BUG_ON(((uintptr_t)aiocbp->aio_buf & (dev->info.sector_size - 1))); + + start = (uintptr_t)aiocbp->aio_buf & PAGE_MASK; + end = ((uintptr_t)aiocbp->aio_buf + aiocbp->aio_nbytes + + PAGE_SIZE - 1) & PAGE_MASK; + n = (end - start) / PAGE_SIZE; + aiocbp->n = n; + + BUG_ON(n > BLKIF_MAX_SEGMENTS_PER_REQUEST); + + blkfront_wait_slot(dev); + i = dev->ring.req_prod_pvt; + req = RING_GET_REQUEST(&dev->ring, i); + + req->operation = write ? BLKIF_OP_WRITE : BLKIF_OP_READ; + req->nr_segments = n; + req->handle = dev->handle; + req->id = (uintptr_t)aiocbp; + req->sector_number = aiocbp->aio_offset / dev->info.sector_size; + + for (j = 0; j < n; j++) { + req->seg[j].first_sect = 0; + req->seg[j].last_sect = PAGE_SIZE / dev->info.sector_size - 1; + } + req->seg[0].first_sect = ((uintptr_t)aiocbp->aio_buf & ~PAGE_MASK) / + dev->info.sector_size; + req->seg[n - 1].last_sect = (((uintptr_t)aiocbp->aio_buf + + aiocbp->aio_nbytes - 1) & ~PAGE_MASK) / dev->info.sector_size; + for (j = 0; j < n; j++) { + uintptr_t data = start + j * PAGE_SIZE; + + if (!write) { + /* Trigger CoW if needed */ + *(char *)(data + (req->seg[j].first_sect * + dev->info.sector_size)) = 0; + barrier(); + } + req->seg[j].gref = gnttab_grant_access(dev->dom, + virt_to_pfn((void *)data), + write); + aiocbp->gref[j] = req->seg[j].gref; + } + + dev->ring.req_prod_pvt = i + 1; + + wmb(); + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&dev->ring, notify); + + if (notify) + notify_remote_via_evtchn(dev->evtchn); +} + +static void blkfront_aio_cb(struct blkfront_aiocb *aiocbp, int ret) +{ + aiocbp->data = (void *)1; + aiocbp->aio_cb = NULL; +} + +static void blkfront_io(struct blkfront_aiocb *aiocbp, int write) +{ + aiocbp->aio_cb = blkfront_aio_cb; + blkfront_aio(aiocbp, write); + aiocbp->data = NULL; + + while (true) { + blkfront_aio_poll(aiocbp->aio_dev); + if (aiocbp->data) + break; + cpu_relax(); + } +} + +static void blkfront_push_operation(struct blkfront_dev *dev, u8 op, + uint64_t id) +{ + struct blkif_request *req; + int notify, i; + + blkfront_wait_slot(dev); + i = dev->ring.req_prod_pvt; + req = RING_GET_REQUEST(&dev->ring, i); + req->operation = op; + req->nr_segments = 0; + req->handle = dev->handle; + req->id = id; + req->sector_number = 0; + dev->ring.req_prod_pvt = i + 1; + wmb(); + RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&dev->ring, notify); + if (notify) + notify_remote_via_evtchn(dev->evtchn); +} + +static void blkfront_sync(struct blkfront_dev *dev) +{ + if (dev->info.mode == O_RDWR) { + if (dev->info.barrier == 1) + blkfront_push_operation(dev, + BLKIF_OP_WRITE_BARRIER, 0); + + if (dev->info.flush == 1) + blkfront_push_operation(dev, + BLKIF_OP_FLUSH_DISKCACHE, 0); + } + + while (true) { + blkfront_aio_poll(dev); + if (RING_FREE_REQUESTS(&dev->ring) == RING_SIZE(&dev->ring)) + break; + cpu_relax(); + } +} + +static ulong pvblock_iop(struct udevice *udev, lbaint_t blknr, + lbaint_t blkcnt, void *buffer, int write) +{ + struct blkfront_dev *blk_dev = dev_get_priv(udev); + struct blk_desc *desc = dev_get_uclass_platdata(udev); + struct blkfront_aiocb aiocb; + lbaint_t blocks_todo; + bool unaligned; + + if (blkcnt == 0) + return 0; + + if ((blknr + blkcnt) > desc->lba) { + printf(DRV_NAME ": block number 0x" LBAF " exceeds max(0x" LBAF ")\n", + blknr + blkcnt, desc->lba); + return 0; + } + + unaligned = (uintptr_t)buffer & (blk_dev->info.sector_size - 1); + + aiocb.aio_dev = blk_dev; + aiocb.aio_offset = blknr * desc->blksz; + aiocb.aio_cb = NULL; + aiocb.data = NULL; + blocks_todo = blkcnt; + do { + aiocb.aio_buf = unaligned ? blk_dev->bounce_buffer : buffer; + + if (write && unaligned) + memcpy(blk_dev->bounce_buffer, buffer, desc->blksz); + + aiocb.aio_nbytes = unaligned ? desc->blksz : + min((size_t)(BLKIF_MAX_SEGMENTS_PER_REQUEST * PAGE_SIZE), + (size_t)(blocks_todo * desc->blksz)); + + blkfront_io(&aiocb, write); + + if (!write && unaligned) + memcpy(buffer, blk_dev->bounce_buffer, desc->blksz); + + aiocb.aio_offset += aiocb.aio_nbytes; + buffer += aiocb.aio_nbytes; + blocks_todo -= aiocb.aio_nbytes / desc->blksz; + } while (blocks_todo > 0); + + return blkcnt; +} + ulong pvblock_blk_read(struct udevice *udev, lbaint_t blknr, lbaint_t blkcnt, void *buffer) { - return 0; + return pvblock_iop(udev, blknr, blkcnt, buffer, 0); }
ulong pvblock_blk_write(struct udevice *udev, lbaint_t blknr, lbaint_t blkcnt, const void *buffer) { - return 0; + return pvblock_iop(udev, blknr, blkcnt, (void *)buffer, 1); }
static int pvblock_blk_bind(struct udevice *udev)