blkio: add libblkio block driver

libblkio (https://gitlab.com/libblkio/libblkio/) is a library for
high-performance disk I/O. It currently supports io_uring,
virtio-blk-vhost-user, and virtio-blk-vhost-vdpa with additional drivers
under development.

One of the reasons for developing libblkio is that other applications
besides QEMU can use it. This will be particularly useful for
virtio-blk-vhost-user which applications may wish to use for connecting
to qemu-storage-daemon.

libblkio also gives us an opportunity to develop in Rust behind a C API
that is easy to consume from QEMU.

This commit adds io_uring, nvme-io_uring, virtio-blk-vhost-user, and
virtio-blk-vhost-vdpa BlockDrivers to QEMU using libblkio. It will be
easy to add other libblkio drivers since they will share the majority of
code.

For now I/O buffers are copied through bounce buffers if the libblkio
driver requires it. Later commits add an optimization for
pre-registering guest RAM to avoid bounce buffers.

The syntax is:

  --blockdev io_uring,node-name=drive0,filename=test.img,readonly=on|off,cache.direct=on|off

  --blockdev nvme-io_uring,node-name=drive0,filename=/dev/ng0n1,readonly=on|off,cache.direct=on

  --blockdev virtio-blk-vhost-vdpa,node-name=drive0,path=/dev/vdpa...,readonly=on|off,cache.direct=on

  --blockdev virtio-blk-vhost-user,node-name=drive0,path=vhost-user-blk.sock,readonly=on|off,cache.direct=on

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20221013185908.1297568-3-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/meson.build b/meson.build
index b686dfef75..1e9068adf6 100644
--- a/meson.build
+++ b/meson.build
@@ -771,6 +771,13 @@ if not get_option('virglrenderer').auto() or have_system or have_vhost_user_gpu
                      required: get_option('virglrenderer'),
                      kwargs: static_kwargs)
 endif
+blkio = not_found
+if not get_option('blkio').auto() or have_block
+  blkio = dependency('blkio',
+                     method: 'pkg-config',
+                     required: get_option('blkio'),
+                     kwargs: static_kwargs)
+endif
 curl = not_found
 if not get_option('curl').auto() or have_block
   curl = dependency('libcurl', version: '>=7.29.0',
@@ -1815,6 +1822,7 @@ config_host_data.set('CONFIG_LIBUDEV', libudev.found())
 config_host_data.set('CONFIG_LZO', lzo.found())
 config_host_data.set('CONFIG_MPATH', mpathpersist.found())
 config_host_data.set('CONFIG_MPATH_NEW_API', mpathpersist_new_api)
+config_host_data.set('CONFIG_BLKIO', blkio.found())
 config_host_data.set('CONFIG_CURL', curl.found())
 config_host_data.set('CONFIG_CURSES', curses.found())
 config_host_data.set('CONFIG_GBM', gbm.found())
@@ -3869,6 +3877,7 @@ summary_info += {'PAM':               pam}
 summary_info += {'iconv support':     iconv}
 summary_info += {'curses support':    curses}
 summary_info += {'virgl support':     virgl}
+summary_info += {'blkio support':     blkio}
 summary_info += {'curl support':      curl}
 summary_info += {'Multipath support': mpathpersist}
 summary_info += {'PNG support':       png}