Merge git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-lguest

* git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-lguest: (45 commits)
  Use "struct boot_params" in example launcher
  Loading bzImage directly.
  Revert lguest magic and use hook in head.S
  Update lguest documentation to reflect the new virtual block device name.
  generalize lgread_u32/lgwrite_u32.
  Example launcher handle guests not being ready for input
  Update example launcher for virtio
  Lguest support for Virtio
  Remove old lguest I/O infrrasructure.
  Remove old lguest bus and drivers.
  Virtio helper routines for a descriptor ringbuffer implementation
  Module autoprobing support for virtio drivers.
  Virtio console driver
  Block driver using virtio.
  Net driver using virtio
  Virtio interface
  Boot with virtual == physical to get closer to native Linux.
  Allow guest to specify syscall vector to use.
  Rename "cr3" to "gpgdir" to avoid x86-specific naming.
  Pagetables to use normal kernel types
  ...

36 files changed, 2911 insertions, 4264 deletions

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 34f40ea0ba6..f4076d9e990 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -94,5 +94,5 @@ source "drivers/kvm/Kconfig"
 
 source "drivers/uio/Kconfig"
 
-source "drivers/lguest/Kconfig"
+source "drivers/virtio/Kconfig"
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index cfe38ffff28..560496b4330 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -91,3 +91,4 @@ obj-$(CONFIG_HID)		+= hid/
 obj-$(CONFIG_PPC_PS3)		+= ps3/
 obj-$(CONFIG_OF)		+= of/
 obj-$(CONFIG_SSB)		+= ssb/
+obj-$(CONFIG_VIRTIO)		+= virtio/
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index ce4b1e484e6..4d0119ea9e3 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -425,4 +425,10 @@ config XEN_BLKDEV_FRONTEND
 	  block device driver.  It communicates with a back-end driver
 	  in another domain which drives the actual block device.
 
+config VIRTIO_BLK
+	tristate "Virtio block driver (EXPERIMENTAL)"
+	depends on EXPERIMENTAL && VIRTIO
+	---help---
+	  This is the virtual block driver for lguest.  Say Y or M.
+
 endif # BLK_DEV
diff --git a/drivers/block/Makefile b/drivers/block/Makefile
index 014e72121b5..7691505a2e1 100644
--- a/drivers/block/Makefile
+++ b/drivers/block/Makefile
@@ -25,10 +25,10 @@ obj-$(CONFIG_SUNVDC)		+= sunvdc.o
 obj-$(CONFIG_BLK_DEV_UMEM)	+= umem.o
 obj-$(CONFIG_BLK_DEV_NBD)	+= nbd.o
 obj-$(CONFIG_BLK_DEV_CRYPTOLOOP) += cryptoloop.o
+obj-$(CONFIG_VIRTIO_BLK)	+= virtio_blk.o
 
 obj-$(CONFIG_VIODASD)		+= viodasd.o
 obj-$(CONFIG_BLK_DEV_SX8)	+= sx8.o
 obj-$(CONFIG_BLK_DEV_UB)	+= ub.o
 
 obj-$(CONFIG_XEN_BLKDEV_FRONTEND)	+= xen-blkfront.o
-obj-$(CONFIG_LGUEST_BLOCK)	+= lguest_blk.o
diff --git a/drivers/block/lguest_blk.c b/drivers/block/lguest_blk.c
deleted file mode 100644
index fa8e42341b8..00000000000
--- a/drivers/block/lguest_blk.c
+++ /dev/null
@@ -1,421 +0,0 @@
-/*D:400
- * The Guest block driver
- *
- * This is a simple block driver, which appears as /dev/lgba, lgbb, lgbc etc.
- * The mechanism is simple: we place the information about the request in the
- * device page, then use SEND_DMA (containing the data for a write, or an empty
- * "ping" DMA for a read).
- :*/
-/* Copyright 2006 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
- */
-//#define DEBUG
-#include <linux/init.h>
-#include <linux/types.h>
-#include <linux/blkdev.h>
-#include <linux/interrupt.h>
-#include <linux/lguest_bus.h>
-
-static char next_block_index = 'a';
-
-/*D:420 Here is the structure which holds all the information we need about
- * each Guest block device.
- *
- * I'm sure at this stage, you're wondering "hey, where was the adventure I was
- * promised?" and thinking "Rusty sucks, I shall say nasty things about him on
- * my blog".  I think Real adventures have boring bits, too, and you're in the
- * middle of one.  But it gets better.  Just not quite yet. */
-struct blockdev
-{
-	/* The block queue infrastructure wants a spinlock: it is held while it
-	 * calls our block request function.  We grab it in our interrupt
-	 * handler so the responses don't mess with new requests. */
-	spinlock_t lock;
-
-	/* The disk structure registered with kernel. */
-	struct gendisk *disk;
-
-	/* The major device number for this disk, and the interrupt.  We only
-	 * really keep them here for completeness; we'd need them if we
-	 * supported device unplugging. */
-	int major;
-	int irq;
-
-	/* The physical address of this device's memory page */
-	unsigned long phys_addr;
-	/* The mapped memory page for convenient acces. */
-	struct lguest_block_page *lb_page;
-
-	/* We only have a single request outstanding at a time: this is it. */
-	struct lguest_dma dma;
-	struct request *req;
-};
-
-/*D:495 We originally used end_request() throughout the driver, but it turns
- * out that end_request() is deprecated, and doesn't actually end the request
- * (which seems like a good reason to deprecate it!).  It simply ends the first
- * bio.  So if we had 3 bios in a "struct request" we would do all 3,
- * end_request(), do 2, end_request(), do 1 and end_request(): twice as much
- * work as we needed to do.
- *
- * This reinforced to me that I do not understand the block layer.
- *
- * Nonetheless, Jens Axboe gave me this nice helper to end all chunks of a
- * request.  This improved disk speed by 130%. */
-static void end_entire_request(struct request *req, int uptodate)
-{
-	if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
-		BUG();
-	add_disk_randomness(req->rq_disk);
-	blkdev_dequeue_request(req);
-	end_that_request_last(req, uptodate);
-}
-
-/* I'm told there are only two stories in the world worth telling: love and
- * hate.  So there used to be a love scene here like this:
- *
- *  Launcher:	We could make beautiful I/O together, you and I.
- *  Guest:	My, that's a big disk!
- *
- * Unfortunately, it was just too raunchy for our otherwise-gentle tale. */
-
-/*D:490 This is the interrupt handler, called when a block read or write has
- * been completed for us. */
-static irqreturn_t lgb_irq(int irq, void *_bd)
-{
-	/* We handed our "struct blockdev" as the argument to request_irq(), so
-	 * it is passed through to us here.  This tells us which device we're
-	 * dealing with in case we have more than one. */
-	struct blockdev *bd = _bd;
-	unsigned long flags;
-
-	/* We weren't doing anything?  Strange, but could happen if we shared
-	 * interrupts (we don't!). */
-	if (!bd->req) {
-		pr_debug("No work!\n");
-		return IRQ_NONE;
-	}
-
-	/* Not done yet?  That's equally strange. */
-	if (!bd->lb_page->result) {
-		pr_debug("No result!\n");
-		return IRQ_NONE;
-	}
-
-	/* We have to grab the lock before ending the request. */
-	spin_lock_irqsave(&bd->lock, flags);
-	/* "result" is 1 for success, 2 for failure: end_entire_request() wants
-	 * to know whether this succeeded or not. */
-	end_entire_request(bd->req, bd->lb_page->result == 1);
-	/* Clear out request, it's done. */
-	bd->req = NULL;
-	/* Reset incoming DMA for next time. */
-	bd->dma.used_len = 0;
-	/* Ready for more reads or writes */
-	blk_start_queue(bd->disk->queue);
-	spin_unlock_irqrestore(&bd->lock, flags);
-
-	/* The interrupt was for us, we dealt with it. */
-	return IRQ_HANDLED;
-}
-
-/*D:480 The block layer's "struct request" contains a number of "struct bio"s,
- * each of which contains "struct bio_vec"s, each of which contains a page, an
- * offset and a length.
- *
- * Fortunately there are iterators to help us walk through the "struct
- * request".  Even more fortunately, there were plenty of places to steal the
- * code from.  We pack the "struct request" into our "struct lguest_dma" and
- * return the total length. */
-static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma)
-{
-	unsigned int i = 0, len = 0;
-	struct req_iterator iter;
-	struct bio_vec *bvec;
-
-	rq_for_each_segment(bvec, req, iter) {
-		/* We told the block layer not to give us too many. */
-		BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
-		/* If we had a zero-length segment, it would look like
-		 * the end of the data referred to by the "struct
-		 * lguest_dma", so make sure that doesn't happen. */
-		BUG_ON(!bvec->bv_len);
-		/* Convert page & offset to a physical address */
-		dma->addr[i] = page_to_phys(bvec->bv_page)
-			+ bvec->bv_offset;
-		dma->len[i] = bvec->bv_len;
-		len += bvec->bv_len;
-		i++;
-	}
-	/* If the array isn't full, we mark the end with a 0 length */
-	if (i < LGUEST_MAX_DMA_SECTIONS)
-		dma->len[i] = 0;
-	return len;
-}
-
-/* This creates an empty DMA, useful for prodding the Host without sending data
- * (ie. when we want to do a read) */
-static void empty_dma(struct lguest_dma *dma)
-{
-	dma->len[0] = 0;
-}
-
-/*D:470 Setting up a request is fairly easy: */
-static void setup_req(struct blockdev *bd,
-		      int type, struct request *req, struct lguest_dma *dma)
-{
-	/* The type is 1 (write) or 0 (read). */
-	bd->lb_page->type = type;
-	/* The sector on disk where the read or write starts. */
-	bd->lb_page->sector = req->sector;
-	/* The result is initialized to 0 (unfinished). */
-	bd->lb_page->result = 0;
-	/* The current request (so we can end it in the interrupt handler). */
-	bd->req = req;
-	/* The number of bytes: returned as a side-effect of req_to_dma(),
-	 * which packs the block layer's "struct request" into our "struct
-	 * lguest_dma" */
-	bd->lb_page->bytes = req_to_dma(req, dma);
-}
-
-/*D:450 Write is pretty straightforward: we pack the request into a "struct
- * lguest_dma", then use SEND_DMA to send the request. */
-static void do_write(struct blockdev *bd, struct request *req)
-{
-	struct lguest_dma send;
-
-	pr_debug("lgb: WRITE sector %li\n", (long)req->sector);
-	setup_req(bd, 1, req, &send);
-
-	lguest_send_dma(bd->phys_addr, &send);
-}
-
-/* Read is similar to write, except we pack the request into our receive
- * "struct lguest_dma" and send through an empty DMA just to tell the Host that
- * there's a request pending. */
-static void do_read(struct blockdev *bd, struct request *req)
-{
-	struct lguest_dma ping;
-
-	pr_debug("lgb: READ sector %li\n", (long)req->sector);
-	setup_req(bd, 0, req, &bd->dma);
-
-	empty_dma(&ping);
-	lguest_send_dma(bd->phys_addr, &ping);
-}
-
-/*D:440 This where requests come in: we get handed the request queue and are
- * expected to pull a "struct request" off it until we've finished them or
- * we're waiting for a reply: */
-static void do_lgb_request(struct request_queue *q)
-{
-	struct blockdev *bd;
-	struct request *req;
-
-again:
-	/* This sometimes returns NULL even on the very first time around.  I
-	 * wonder if it's something to do with letting elves handle the request
-	 * queue... */
-	req = elv_next_request(q);
-	if (!req)
-		return;
-
-	/* We attached the struct blockdev to the disk: get it back */
-	bd = req->rq_disk->private_data;
-	/* Sometimes we get repeated requests after blk_stop_queue(), but we
-	 * can only handle one at a time. */
-	if (bd->req)
-		return;
-
-	/* We only do reads and writes: no tricky business! */
-	if (!blk_fs_request(req)) {
-		pr_debug("Got non-command 0x%08x\n", req->cmd_type);
-		req->errors++;
-		end_entire_request(req, 0);
-		goto again;
-	}
-
-	if (rq_data_dir(req) == WRITE)
-		do_write(bd, req);
-	else
-		do_read(bd, req);
-
-	/* We've put out the request, so stop any more coming in until we get
-	 * an interrupt, which takes us to lgb_irq() to re-enable the queue. */
-	blk_stop_queue(q);
-}
-
-/*D:430 This is the "struct block_device_operations" we attach to the disk at
- * the end of lguestblk_probe().  It doesn't seem to want much. */
-static struct block_device_operations lguestblk_fops = {
-	.owner = THIS_MODULE,
-};
-
-/*D:425 Setting up a disk device seems to involve a lot of code.  I'm not sure
- * quite why.  I do know that the IDE code sent two or three of the maintainers
- * insane, perhaps this is the fringe of the same disease?
- *
- * As in the console code, the probe function gets handed the generic
- * lguest_device from lguest_bus.c: */
-static int lguestblk_probe(struct lguest_device *lgdev)
-{
-	struct blockdev *bd;
-	int err;
-	int irqflags = IRQF_SHARED;
-
-	/* First we allocate our own "struct blockdev" and initialize the easy
-	 * fields. */
-	bd = kmalloc(sizeof(*bd), GFP_KERNEL);
-	if (!bd)
-		return -ENOMEM;
-
-	spin_lock_init(&bd->lock);
-	bd->irq = lgdev_irq(lgdev);
-	bd->req = NULL;
-	bd->dma.used_len = 0;
-	bd->dma.len[0] = 0;
-	/* The descriptor in the lguest_devices array provided by the Host
-	 * gives the Guest the physical page number of the device's page. */
-	bd->phys_addr = (lguest_devices[lgdev->index].pfn << PAGE_SHIFT);
-
-	/* We use lguest_map() to get a pointer to the device page */
-	bd->lb_page = lguest_map(bd->phys_addr, 1);
-	if (!bd->lb_page) {
-		err = -ENOMEM;
-		goto out_free_bd;
-	}
-
-	/* We need a major device number: 0 means "assign one dynamically". */
-	bd->major = register_blkdev(0, "lguestblk");
-	if (bd->major < 0) {
-		err = bd->major;
-		goto out_unmap;
-	}
-
-	/* This allocates a "struct gendisk" where we pack all the information
-	 * about the disk which the rest of Linux sees.  The argument is the
-	 * number of minor devices desired: we need one minor for the main
-	 * disk, and one for each partition.  Of course, we can't possibly know
-	 * how many partitions are on the disk (add_disk does that).
-	 */
-	bd->disk = alloc_disk(16);
-	if (!bd->disk) {
-		err = -ENOMEM;
-		goto out_unregister_blkdev;
-	}
-
-	/* Every disk needs a queue for requests to come in: we set up the
-	 * queue with a callback function (the core of our driver) and the lock
-	 * to use. */
-	bd->disk->queue = blk_init_queue(do_lgb_request, &bd->lock);
-	if (!bd->disk->queue) {
-		err = -ENOMEM;
-		goto out_put_disk;
-	}
-
-	/* We can only handle a certain number of pointers in our SEND_DMA
-	 * call, so we set that with blk_queue_max_hw_segments().  This is not
-	 * to be confused with blk_queue_max_phys_segments() of course!  I
-	 * know, who could possibly confuse the two?
-	 *
-	 * Well, it's simple to tell them apart: this one seems to work and the
-	 * other one didn't. */
-	blk_queue_max_hw_segments(bd->disk->queue, LGUEST_MAX_DMA_SECTIONS);
-
-	/* Due to technical limitations of our Host (and simple coding) we
-	 * can't have a single buffer which crosses a page boundary.  Tell it
-	 * here.  This means that our maximum request size is 16
-	 * (LGUEST_MAX_DMA_SECTIONS) pages. */
-	blk_queue_segment_boundary(bd->disk->queue, PAGE_SIZE-1);
-
-	/* We name our disk: this becomes the device name when udev does its
-	 * magic thing and creates the device node, such as /dev/lgba.
-	 * next_block_index is a global which starts at 'a'.  Unfortunately
-	 * this simple increment logic means that the 27th disk will be called
-	 * "/dev/lgb{".  In that case, I recommend having at least 29 disks, so
-	 * your /dev directory will be balanced. */
-	sprintf(bd->disk->disk_name, "lgb%c", next_block_index++);
-
-	/* We look to the device descriptor again to see if this device's
-	 * interrupts are expected to be random.  If they are, we tell the irq
-	 * subsystem.  At the moment this bit is always set. */
-	if (lguest_devices[lgdev->index].features & LGUEST_DEVICE_F_RANDOMNESS)
-		irqflags |= IRQF_SAMPLE_RANDOM;
-
-	/* Now we have the name and irqflags, we can request the interrupt; we
-	 * give it the "struct blockdev" we have set up to pass to lgb_irq()
-	 * when there is an interrupt. */
-	err = request_irq(bd->irq, lgb_irq, irqflags, bd->disk->disk_name, bd);
-	if (err)
-		goto out_cleanup_queue;
-
-	/* We bind our one-entry DMA pool to the key for this block device so
-	 * the Host can reply to our requests.  The key is equal to the
-	 * physical address of the device's page, which is conveniently
-	 * unique. */
-	err = lguest_bind_dma(bd->phys_addr, &bd->dma, 1, bd->irq);
-	if (err)
-		goto out_free_irq;
-
-	/* We finish our disk initialization and add the disk to the system. */
-	bd->disk->major = bd->major;
-	bd->disk->first_minor = 0;
-	bd->disk->private_data = bd;
-	bd->disk->fops = &lguestblk_fops;
-	/* This is initialized to the disk size by the Launcher. */
-	set_capacity(bd->disk, bd->lb_page->num_sectors);
-	add_disk(bd->disk);
-
-	printk(KERN_INFO "%s: device %i at major %d\n",
-	       bd->disk->disk_name, lgdev->index, bd->major);
-
-	/* We don't need to keep the "struct blockdev" around, but if we ever
-	 * implemented device removal, we'd need this. */
-	lgdev->private = bd;
-	return 0;
-
-out_free_irq:
-	free_irq(bd->irq, bd);
-out_cleanup_queue:
-	blk_cleanup_queue(bd->disk->queue);
-out_put_disk:
-	put_disk(bd->disk);
-out_unregister_blkdev:
-	unregister_blkdev(bd->major, "lguestblk");
-out_unmap:
-	lguest_unmap(bd->lb_page);
-out_free_bd:
-	kfree(bd);
-	return err;
-}
-
-/*D:410 The boilerplate code for registering the lguest block driver is just
- * like the console: */
-static struct lguest_driver lguestblk_drv = {
-	.name = "lguestblk",
-	.owner = THIS_MODULE,
-	.device_type = LGUEST_DEVICE_T_BLOCK,
-	.probe = lguestblk_probe,
-};
-
-static __init int lguestblk_init(void)
-{
-	return register_lguest_driver(&lguestblk_drv);
-}
-module_init(lguestblk_init);
-
-MODULE_DESCRIPTION("Lguest block driver");
-MODULE_LICENSE("GPL");
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
new file mode 100644
index 00000000000..a901eee64ba
--- /dev/null
+++ b/drivers/block/virtio_blk.c
@@ -0,0 +1,308 @@
+//#define DEBUG
+#include <linux/spinlock.h>
+#include <linux/blkdev.h>
+#include <linux/hdreg.h>
+#include <linux/virtio.h>
+#include <linux/virtio_blk.h>
+#include <linux/virtio_blk.h>
+
+static unsigned char virtblk_index = 'a';
+struct virtio_blk
+{
+	spinlock_t lock;
+
+	struct virtio_device *vdev;
+	struct virtqueue *vq;
+
+	/* The disk structure for the kernel. */
+	struct gendisk *disk;
+
+	/* Request tracking. */
+	struct list_head reqs;
+
+	mempool_t *pool;
+
+	/* Scatterlist: can be too big for stack. */
+	struct scatterlist sg[3+MAX_PHYS_SEGMENTS];
+};
+
+struct virtblk_req
+{
+	struct list_head list;
+	struct request *req;
+	struct virtio_blk_outhdr out_hdr;
+	struct virtio_blk_inhdr in_hdr;
+};
+
+static bool blk_done(struct virtqueue *vq)
+{
+	struct virtio_blk *vblk = vq->vdev->priv;
+	struct virtblk_req *vbr;
+	unsigned int len;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vblk->lock, flags);
+	while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) {
+		int uptodate;
+		switch (vbr->in_hdr.status) {
+		case VIRTIO_BLK_S_OK:
+			uptodate = 1;
+			break;
+		case VIRTIO_BLK_S_UNSUPP:
+			uptodate = -ENOTTY;
+			break;
+		default:
+			uptodate = 0;
+			break;
+		}
+
+		end_dequeued_request(vbr->req, uptodate);
+		list_del(&vbr->list);
+		mempool_free(vbr, vblk->pool);
+	}
+	/* In case queue is stopped waiting for more buffers. */
+	blk_start_queue(vblk->disk->queue);
+	spin_unlock_irqrestore(&vblk->lock, flags);
+	return true;
+}
+
+static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
+		   struct request *req)
+{
+	unsigned long num, out, in;
+	struct virtblk_req *vbr;
+
+	vbr = mempool_alloc(vblk->pool, GFP_ATOMIC);
+	if (!vbr)
+		/* When another request finishes we'll try again. */
+		return false;
+
+	vbr->req = req;
+	if (blk_fs_request(vbr->req)) {
+		vbr->out_hdr.type = 0;
+		vbr->out_hdr.sector = vbr->req->sector;
+		vbr->out_hdr.ioprio = vbr->req->ioprio;
+	} else if (blk_pc_request(vbr->req)) {
+		vbr->out_hdr.type = VIRTIO_BLK_T_SCSI_CMD;
+		vbr->out_hdr.sector = 0;
+		vbr->out_hdr.ioprio = vbr->req->ioprio;
+	} else {
+		/* We don't put anything else in the queue. */
+		BUG();
+	}
+
+	if (blk_barrier_rq(vbr->req))
+		vbr->out_hdr.type |= VIRTIO_BLK_T_BARRIER;
+
+	/* We have to zero this, otherwise blk_rq_map_sg gets upset. */
+	memset(vblk->sg, 0, sizeof(vblk->sg));
+	sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr));
+	num = blk_rq_map_sg(q, vbr->req, vblk->sg+1);
+	sg_set_buf(&vblk->sg[num+1], &vbr->in_hdr, sizeof(vbr->in_hdr));
+
+	if (rq_data_dir(vbr->req) == WRITE) {
+		vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
+		out = 1 + num;
+		in = 1;
+	} else {
+		vbr->out_hdr.type |= VIRTIO_BLK_T_IN;
+		out = 1;
+		in = 1 + num;
+	}
+
+	if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) {
+		mempool_free(vbr, vblk->pool);
+		return false;
+	}
+
+	list_add_tail(&vbr->list, &vblk->reqs);
+	return true;
+}
+
+static void do_virtblk_request(struct request_queue *q)
+{
+	struct virtio_blk *vblk = NULL;
+	struct request *req;
+	unsigned int issued = 0;
+
+	while ((req = elv_next_request(q)) != NULL) {
+		vblk = req->rq_disk->private_data;
+		BUG_ON(req->nr_phys_segments > ARRAY_SIZE(vblk->sg));
+
+		/* If this request fails, stop queue and wait for something to
+		   finish to restart it. */
+		if (!do_req(q, vblk, req)) {
+			blk_stop_queue(q);
+			break;
+		}
+		blkdev_dequeue_request(req);
+		issued++;
+	}
+
+	if (issued)
+		vblk->vq->vq_ops->kick(vblk->vq);
+}
+
+static int virtblk_ioctl(struct inode *inode, struct file *filp,
+			 unsigned cmd, unsigned long data)
+{
+	return scsi_cmd_ioctl(filp, inode->i_bdev->bd_disk->queue,
+			      inode->i_bdev->bd_disk, cmd,
+			      (void __user *)data);
+}
+
+static struct block_device_operations virtblk_fops = {
+	.ioctl = virtblk_ioctl,
+	.owner = THIS_MODULE,
+};
+
+static int virtblk_probe(struct virtio_device *vdev)
+{
+	struct virtio_blk *vblk;
+	int err, major;
+	void *token;
+	unsigned int len;
+	u64 cap;
+	u32 v;
+
+	vdev->priv = vblk = kmalloc(sizeof(*vblk), GFP_KERNEL);
+	if (!vblk) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	INIT_LIST_HEAD(&vblk->reqs);
+	spin_lock_init(&vblk->lock);
+	vblk->vdev = vdev;
+
+	/* We expect one virtqueue, for output. */
+	vblk->vq = vdev->config->find_vq(vdev, blk_done);
+	if (IS_ERR(vblk->vq)) {
+		err = PTR_ERR(vblk->vq);
+		goto out_free_vblk;
+	}
+
+	vblk->pool = mempool_create_kmalloc_pool(1,sizeof(struct virtblk_req));
+	if (!vblk->pool) {
+		err = -ENOMEM;
+		goto out_free_vq;
+	}
+
+	major = register_blkdev(0, "virtblk");
+	if (major < 0) {
+		err = major;
+		goto out_mempool;
+	}
+
+	/* FIXME: How many partitions?  How long is a piece of string? */
+	vblk->disk = alloc_disk(1 << 4);
+	if (!vblk->disk) {
+		err = -ENOMEM;
+		goto out_unregister_blkdev;
+	}
+
+	vblk->disk->queue = blk_init_queue(do_virtblk_request, &vblk->lock);
+	if (!vblk->disk->queue) {
+		err = -ENOMEM;
+		goto out_put_disk;
+	}
+
+	sprintf(vblk->disk->disk_name, "vd%c", virtblk_index++);
+	vblk->disk->major = major;
+	vblk->disk->first_minor = 0;
+	vblk->disk->private_data = vblk;
+	vblk->disk->fops = &virtblk_fops;
+
+	/* If barriers are supported, tell block layer that queue is ordered */
+	token = vdev->config->find(vdev, VIRTIO_CONFIG_BLK_F, &len);
+	if (virtio_use_bit(vdev, token, len, VIRTIO_BLK_F_BARRIER))
+		blk_queue_ordered(vblk->disk->queue, QUEUE_ORDERED_TAG, NULL);
+
+	err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_CAPACITY, &cap);
+	if (err) {
+		dev_err(&vdev->dev, "Bad/missing capacity in config\n");
+		goto out_put_disk;
+	}
+
+	/* If capacity is too big, truncate with warning. */
+	if ((sector_t)cap != cap) {
+		dev_warn(&vdev->dev, "Capacity %llu too large: truncating\n",
+			 (unsigned long long)cap);
+		cap = (sector_t)-1;
+	}
+	set_capacity(vblk->disk, cap);
+
+	err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SIZE_MAX, &v);
+	if (!err)
+		blk_queue_max_segment_size(vblk->disk->queue, v);
+	else if (err != -ENOENT) {
+		dev_err(&vdev->dev, "Bad SIZE_MAX in config\n");
+		goto out_put_disk;
+	}
+
+	err = virtio_config_val(vdev, VIRTIO_CONFIG_BLK_F_SEG_MAX, &v);
+	if (!err)
+		blk_queue_max_hw_segments(vblk->disk->queue, v);
+	else if (err != -ENOENT) {
+		dev_err(&vdev->dev, "Bad SEG_MAX in config\n");
+		goto out_put_disk;
+	}
+
+	add_disk(vblk->disk);
+	return 0;
+
+out_put_disk:
+	put_disk(vblk->disk);
+out_unregister_blkdev:
+	unregister_blkdev(major, "virtblk");
+out_mempool:
+	mempool_destroy(vblk->pool);
+out_free_vq:
+	vdev->config->del_vq(vblk->vq);
+out_free_vblk:
+	kfree(vblk);
+out:
+	return err;
+}
+
+static void virtblk_remove(struct virtio_device *vdev)
+{
+	struct virtio_blk *vblk = vdev->priv;
+	int major = vblk->disk->major;
+
+	BUG_ON(!list_empty(&vblk->reqs));
+	blk_cleanup_queue(vblk->disk->queue);
+	put_disk(vblk->disk);
+	unregister_blkdev(major, "virtblk");
+	mempool_destroy(vblk->pool);
+	kfree(vblk);
+}
+
+static struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_BLOCK, VIRTIO_DEV_ANY_ID },
+	{ 0 },
+};
+
+static struct virtio_driver virtio_blk = {
+	.driver.name =	KBUILD_MODNAME,
+	.driver.owner =	THIS_MODULE,
+	.id_table =	id_table,
+	.probe =	virtblk_probe,
+	.remove =	__devexit_p(virtblk_remove),
+};
+
+static int __init init(void)
+{
+	return register_virtio_driver(&virtio_b