Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 312 insertions, 0 deletions

diff --git a/block/bochs.c b/block/bochs.c
new file mode 100644
index 000000000..4d6865808
--- /dev/null
+++ b/block/bochs.c
@@ -0,0 +1,312 @@
+/*
+ * Block driver for the various disk image formats used by Bochs
+ * Currently only for "growing" type in read-only mode
+ *
+ * Copyright (c) 2005 Alex Beregszaszi
+ *
+ * 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 "qemu/osdep.h"
+#include "qapi/error.h"
+#include "block/block_int.h"
+#include "qemu/module.h"
+#include "qemu/bswap.h"
+#include "qemu/error-report.h"
+
+/**************************************************************/
+
+#define HEADER_MAGIC "Bochs Virtual HD Image"
+#define HEADER_VERSION 0x00020000
+#define HEADER_V1 0x00010000
+#define HEADER_SIZE 512
+
+#define REDOLOG_TYPE "Redolog"
+#define GROWING_TYPE "Growing"
+
+// not allocated: 0xffffffff
+
+// always little-endian
+struct bochs_header {
+    char magic[32];     /* "Bochs Virtual HD Image" */
+    char type[16];      /* "Redolog" */
+    char subtype[16];   /* "Undoable" / "Volatile" / "Growing" */
+    uint32_t version;
+    uint32_t header;    /* size of header */
+
+    uint32_t catalog;   /* num of entries */
+    uint32_t bitmap;    /* bitmap size */
+    uint32_t extent;    /* extent size */
+
+    union {
+        struct {
+            uint32_t reserved;  /* for ??? */
+            uint64_t disk;      /* disk size */
+            char padding[HEADER_SIZE - 64 - 20 - 12];
+        } QEMU_PACKED redolog;
+        struct {
+            uint64_t disk;      /* disk size */
+            char padding[HEADER_SIZE - 64 - 20 - 8];
+        } QEMU_PACKED redolog_v1;
+        char padding[HEADER_SIZE - 64 - 20];
+    } extra;
+} QEMU_PACKED;
+
+typedef struct BDRVBochsState {
+    CoMutex lock;
+    uint32_t *catalog_bitmap;
+    uint32_t catalog_size;
+
+    uint32_t data_offset;
+
+    uint32_t bitmap_blocks;
+    uint32_t extent_blocks;
+    uint32_t extent_size;
+} BDRVBochsState;
+
+static int bochs_probe(const uint8_t *buf, int buf_size, const char *filename)
+{
+    const struct bochs_header *bochs = (const void *)buf;
+
+    if (buf_size < HEADER_SIZE)
+        return 0;
+
+    if (!strcmp(bochs->magic, HEADER_MAGIC) &&
+        !strcmp(bochs->type, REDOLOG_TYPE) &&
+        !strcmp(bochs->subtype, GROWING_TYPE) &&
+        ((le32_to_cpu(bochs->version) == HEADER_VERSION) ||
+        (le32_to_cpu(bochs->version) == HEADER_V1)))
+        return 100;
+
+    return 0;
+}
+
+static int bochs_open(BlockDriverState *bs, QDict *options, int flags,
+                      Error **errp)
+{
+    BDRVBochsState *s = bs->opaque;
+    uint32_t i;
+    struct bochs_header bochs;
+    int ret;
+
+    /* No write support yet */
+    ret = bdrv_apply_auto_read_only(bs, NULL, errp);
+    if (ret < 0) {
+        return ret;
+    }
+
+    bs->file = bdrv_open_child(NULL, options, "file", bs, &child_of_bds,
+                               BDRV_CHILD_IMAGE, false, errp);
+    if (!bs->file) {
+        return -EINVAL;
+    }
+
+    ret = bdrv_pread(bs->file, 0, &bochs, sizeof(bochs));
+    if (ret < 0) {
+        return ret;
+    }
+
+    if (strcmp(bochs.magic, HEADER_MAGIC) ||
+        strcmp(bochs.type, REDOLOG_TYPE) ||
+        strcmp(bochs.subtype, GROWING_TYPE) ||
+        ((le32_to_cpu(bochs.version) != HEADER_VERSION) &&
+        (le32_to_cpu(bochs.version) != HEADER_V1))) {
+        error_setg(errp, "Image not in Bochs format");
+        return -EINVAL;
+    }
+
+    if (le32_to_cpu(bochs.version) == HEADER_V1) {
+        bs->total_sectors = le64_to_cpu(bochs.extra.redolog_v1.disk) / 512;
+    } else {
+        bs->total_sectors = le64_to_cpu(bochs.extra.redolog.disk) / 512;
+    }
+
+    /* Limit to 1M entries to avoid unbounded allocation. This is what is
+     * needed for the largest image that bximage can create (~8 TB). */
+    s->catalog_size = le32_to_cpu(bochs.catalog);
+    if (s->catalog_size > 0x100000) {
+        error_setg(errp, "Catalog size is too large");
+        return -EFBIG;
+    }
+
+    s->catalog_bitmap = g_try_new(uint32_t, s->catalog_size);
+    if (s->catalog_size && s->catalog_bitmap == NULL) {
+        error_setg(errp, "Could not allocate memory for catalog");
+        return -ENOMEM;
+    }
+
+    ret = bdrv_pread(bs->file, le32_to_cpu(bochs.header), s->catalog_bitmap,
+                     s->catalog_size * 4);
+    if (ret < 0) {
+        goto fail;
+    }
+
+    for (i = 0; i < s->catalog_size; i++)
+        le32_to_cpus(&s->catalog_bitmap[i]);
+
+    s->data_offset = le32_to_cpu(bochs.header) + (s->catalog_size * 4);
+
+    s->bitmap_blocks = 1 + (le32_to_cpu(bochs.bitmap) - 1) / 512;
+    s->extent_blocks = 1 + (le32_to_cpu(bochs.extent) - 1) / 512;
+
+    s->extent_size = le32_to_cpu(bochs.extent);
+    if (s->extent_size < BDRV_SECTOR_SIZE) {
+        /* bximage actually never creates extents smaller than 4k */
+        error_setg(errp, "Extent size must be at least 512");
+        ret = -EINVAL;
+        goto fail;
+    } else if (!is_power_of_2(s->extent_size)) {
+        error_setg(errp, "Extent size %" PRIu32 " is not a power of two",
+                   s->extent_size);
+        ret = -EINVAL;
+        goto fail;
+    } else if (s->extent_size > 0x800000) {
+        error_setg(errp, "Extent size %" PRIu32 " is too large",
+                   s->extent_size);
+        ret = -EINVAL;
+        goto fail;
+    }
+
+    if (s->catalog_size < DIV_ROUND_UP(bs->total_sectors,
+                                       s->extent_size / BDRV_SECTOR_SIZE))
+    {
+        error_setg(errp, "Catalog size is too small for this disk size");
+        ret = -EINVAL;
+        goto fail;
+    }
+
+    qemu_co_mutex_init(&s->lock);
+    return 0;
+
+fail:
+    g_free(s->catalog_bitmap);
+    return ret;
+}
+
+static void bochs_refresh_limits(BlockDriverState *bs, Error **errp)
+{
+    bs->bl.request_alignment = BDRV_SECTOR_SIZE; /* No sub-sector I/O */
+}
+
+static int64_t seek_to_sector(BlockDriverState *bs, int64_t sector_num)
+{
+    BDRVBochsState *s = bs->opaque;
+    uint64_t offset = sector_num * 512;
+    uint64_t extent_index, extent_offset, bitmap_offset;
+    char bitmap_entry;
+    int ret;
+
+    // seek to sector
+    extent_index = offset / s->extent_size;
+    extent_offset = (offset % s->extent_size) / 512;
+
+    if (s->catalog_bitmap[extent_index] == 0xffffffff) {
+        return 0; /* not allocated */
+    }
+
+    bitmap_offset = s->data_offset +
+        (512 * (uint64_t) s->catalog_bitmap[extent_index] *
+        (s->extent_blocks + s->bitmap_blocks));
+
+    /* read in bitmap for current extent */
+    ret = bdrv_pread(bs->file, bitmap_offset + (extent_offset / 8),
+                     &bitmap_entry, 1);
+    if (ret < 0) {
+        return ret;
+    }
+
+    if (!((bitmap_entry >> (extent_offset % 8)) & 1)) {
+        return 0; /* not allocated */
+    }
+
+    return bitmap_offset + (512 * (s->bitmap_blocks + extent_offset));
+}
+
+static int coroutine_fn
+bochs_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
+                QEMUIOVector *qiov, BdrvRequestFlags flags)
+{
+    BDRVBochsState *s = bs->opaque;
+    uint64_t sector_num = offset >> BDRV_SECTOR_BITS;
+    int nb_sectors = bytes >> BDRV_SECTOR_BITS;
+    uint64_t bytes_done = 0;
+    QEMUIOVector local_qiov;
+    int ret;
+
+    assert(QEMU_IS_ALIGNED(offset, BDRV_SECTOR_SIZE));
+    assert(QEMU_IS_ALIGNED(bytes, BDRV_SECTOR_SIZE));
+
+    qemu_iovec_init(&local_qiov, qiov->niov);
+    qemu_co_mutex_lock(&s->lock);
+
+    while (nb_sectors > 0) {
+        int64_t block_offset = seek_to_sector(bs, sector_num);
+        if (block_offset < 0) {
+            ret = block_offset;
+            goto fail;
+        }
+
+        qemu_iovec_reset(&local_qiov);
+        qemu_iovec_concat(&local_qiov, qiov, bytes_done, 512);
+
+        if (block_offset > 0) {
+            ret = bdrv_co_preadv(bs->file, block_offset, 512,
+                                 &local_qiov, 0);
+            if (ret < 0) {
+                goto fail;
+            }
+        } else {
+            qemu_iovec_memset(&local_qiov, 0, 0, 512);
+        }
+        nb_sectors--;
+        sector_num++;
+        bytes_done += 512;
+    }
+
+    ret = 0;
+fail:
+    qemu_co_mutex_unlock(&s->lock);
+    qemu_iovec_destroy(&local_qiov);
+
+    return ret;
+}
+
+static void bochs_close(BlockDriverState *bs)
+{
+    BDRVBochsState *s = bs->opaque;
+    g_free(s->catalog_bitmap);
+}
+
+static BlockDriver bdrv_bochs = {
+    .format_name	= "bochs",
+    .instance_size	= sizeof(BDRVBochsState),
+    .bdrv_probe		= bochs_probe,
+    .bdrv_open		= bochs_open,
+    .bdrv_child_perm     = bdrv_default_perms,
+    .bdrv_refresh_limits = bochs_refresh_limits,
+    .bdrv_co_preadv = bochs_co_preadv,
+    .bdrv_close		= bochs_close,
+    .is_format          = true,
+};
+
+static void bdrv_bochs_init(void)
+{
+    bdrv_register(&bdrv_bochs);
+}
+
+block_init(bdrv_bochs_init);