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f41520402c
qemu/block/blkio.c
Stefano Garzarella cad2ccc395 block/blkio: use qemu_open() to support fd passing for virtio-blk 
Some virtio-blk drivers (e.g. virtio-blk-vhost-vdpa) supports the fd
passing. Let's expose this to the user, so the management layer
can pass the file descriptor of an already opened path.

If the libblkio virtio-blk driver supports fd passing, let's always
use qemu_open() to open the `path`, so we can handle fd passing
from the management layer through the "/dev/fdset/N" special path.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Message-id: 20230530071941.8954-2-sgarzare@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
2023-06-01 11:08:21 -04:00

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/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
* libblkio BlockDriver
*
* Copyright Red Hat, Inc.
*
* Author:
* Stefan Hajnoczi <stefanha@redhat.com>
*/
#include "qemu/osdep.h"
#include <blkio.h>
#include "block/block_int.h"
#include "exec/memory.h"
#include "exec/cpu-common.h" /* for qemu_ram_get_fd() */
#include "qapi/error.h"
#include "qemu/error-report.h"
#include "qapi/qmp/qdict.h"
#include "qemu/module.h"
#include "sysemu/block-backend.h"
#include "exec/memory.h" /* for ram_block_discard_disable() */
#include "block/block-io.h"
/*
* Keep the QEMU BlockDriver names identical to the libblkio driver names.
* Using macros instead of typing out the string literals avoids typos.
*/
#define DRIVER_IO_URING "io_uring"
#define DRIVER_NVME_IO_URING "nvme-io_uring"
#define DRIVER_VIRTIO_BLK_VFIO_PCI "virtio-blk-vfio-pci"
#define DRIVER_VIRTIO_BLK_VHOST_USER "virtio-blk-vhost-user"
#define DRIVER_VIRTIO_BLK_VHOST_VDPA "virtio-blk-vhost-vdpa"
/*
* Allocated bounce buffers are kept in a list sorted by buffer address.
*/
typedef struct BlkioBounceBuf {
QLIST_ENTRY(BlkioBounceBuf) next;
/* The bounce buffer */
struct iovec buf;
} BlkioBounceBuf;
typedef struct {
/*
* libblkio is not thread-safe so this lock protects ->blkio and
* ->blkioq.
*/
QemuMutex blkio_lock;
struct blkio *blkio;
struct blkioq *blkioq; /* make this multi-queue in the future... */
int completion_fd;
/*
* Polling fetches the next completion into this field.
*
* No lock is necessary since only one thread calls aio_poll() and invokes
* fd and poll handlers.
*/
struct blkio_completion poll_completion;
/*
* Protects ->bounce_pool, ->bounce_bufs, ->bounce_available.
*
* Lock ordering: ->bounce_lock before ->blkio_lock.
*/
CoMutex bounce_lock;
/* Bounce buffer pool */
struct blkio_mem_region bounce_pool;
/* Sorted list of allocated bounce buffers */
QLIST_HEAD(, BlkioBounceBuf) bounce_bufs;
/* Queue for coroutines waiting for bounce buffer space */
CoQueue bounce_available;
/* The value of the "mem-region-alignment" property */
size_t mem_region_alignment;
/* Can we skip adding/deleting blkio_mem_regions? */
bool needs_mem_regions;
/* Are file descriptors necessary for blkio_mem_regions? */
bool needs_mem_region_fd;
/* Are madvise(MADV_DONTNEED)-style operations unavailable? */
bool may_pin_mem_regions;
} BDRVBlkioState;
/* Called with s->bounce_lock held */
static int blkio_resize_bounce_pool(BDRVBlkioState *s, int64_t bytes)
{
/* There can be no allocated bounce buffers during resize */
assert(QLIST_EMPTY(&s->bounce_bufs));
/* Pad size to reduce frequency of resize calls */
bytes += 128 * 1024;
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
int ret;
if (s->bounce_pool.addr) {
blkio_unmap_mem_region(s->blkio, &s->bounce_pool);
blkio_free_mem_region(s->blkio, &s->bounce_pool);
memset(&s->bounce_pool, 0, sizeof(s->bounce_pool));
}
/* Automatically freed when s->blkio is destroyed */
ret = blkio_alloc_mem_region(s->blkio, &s->bounce_pool, bytes);
if (ret < 0) {
return ret;
}
ret = blkio_map_mem_region(s->blkio, &s->bounce_pool);
if (ret < 0) {
blkio_free_mem_region(s->blkio, &s->bounce_pool);
memset(&s->bounce_pool, 0, sizeof(s->bounce_pool));
return ret;
}
}
return 0;
}
/* Called with s->bounce_lock held */
static bool
blkio_do_alloc_bounce_buffer(BDRVBlkioState *s, BlkioBounceBuf *bounce,
int64_t bytes)
{
void *addr = s->bounce_pool.addr;
BlkioBounceBuf *cur = NULL;
BlkioBounceBuf *prev = NULL;
ptrdiff_t space;
/*
* This is just a linear search over the holes between requests. An
* efficient allocator would be nice.
*/
QLIST_FOREACH(cur, &s->bounce_bufs, next) {
space = cur->buf.iov_base - addr;
if (bytes <= space) {
QLIST_INSERT_BEFORE(cur, bounce, next);
bounce->buf.iov_base = addr;
bounce->buf.iov_len = bytes;
return true;
}
addr = cur->buf.iov_base + cur->buf.iov_len;
prev = cur;
}
/* Is there space after the last request? */
space = s->bounce_pool.addr + s->bounce_pool.len - addr;
if (bytes > space) {
return false;
}
if (prev) {
QLIST_INSERT_AFTER(prev, bounce, next);
} else {
QLIST_INSERT_HEAD(&s->bounce_bufs, bounce, next);
}
bounce->buf.iov_base = addr;
bounce->buf.iov_len = bytes;
return true;
}
static int coroutine_fn
blkio_alloc_bounce_buffer(BDRVBlkioState *s, BlkioBounceBuf *bounce,
int64_t bytes)
{
/*
* Ensure fairness: first time around we join the back of the queue,
* subsequently we join the front so we don't lose our place.
*/
CoQueueWaitFlags wait_flags = 0;
QEMU_LOCK_GUARD(&s->bounce_lock);
/* Ensure fairness: don't even try if other requests are already waiting */
if (!qemu_co_queue_empty(&s->bounce_available)) {
qemu_co_queue_wait_flags(&s->bounce_available, &s->bounce_lock,
wait_flags);
wait_flags = CO_QUEUE_WAIT_FRONT;
}
while (true) {
if (blkio_do_alloc_bounce_buffer(s, bounce, bytes)) {
/* Kick the next queued request since there may be space */
qemu_co_queue_next(&s->bounce_available);
return 0;
}
/*
* If there are no in-flight requests then the pool was simply too
* small.
*/
if (QLIST_EMPTY(&s->bounce_bufs)) {
bool ok;
int ret;
ret = blkio_resize_bounce_pool(s, bytes);
if (ret < 0) {
/* Kick the next queued request since that may fail too */
qemu_co_queue_next(&s->bounce_available);
return ret;
}
ok = blkio_do_alloc_bounce_buffer(s, bounce, bytes);
assert(ok); /* must have space this time */
return 0;
}
qemu_co_queue_wait_flags(&s->bounce_available, &s->bounce_lock,
wait_flags);
wait_flags = CO_QUEUE_WAIT_FRONT;
}
}
static void coroutine_fn blkio_free_bounce_buffer(BDRVBlkioState *s,
BlkioBounceBuf *bounce)
{
QEMU_LOCK_GUARD(&s->bounce_lock);
QLIST_REMOVE(bounce, next);
/* Wake up waiting coroutines since space may now be available */
qemu_co_queue_next(&s->bounce_available);
}
/* For async to .bdrv_co_*() conversion */
typedef struct {
Coroutine *coroutine;
int ret;
} BlkioCoData;
static void blkio_completion_fd_read(void *opaque)
{
BlockDriverState *bs = opaque;
BDRVBlkioState *s = bs->opaque;
uint64_t val;
int ret;
/* Polling may have already fetched a completion */
if (s->poll_completion.user_data != NULL) {
BlkioCoData *cod = s->poll_completion.user_data;
cod->ret = s->poll_completion.ret;
/* Clear it in case aio_co_wake() enters a nested event loop */
s->poll_completion.user_data = NULL;
aio_co_wake(cod->coroutine);
}
/* Reset completion fd status */
ret = read(s->completion_fd, &val, sizeof(val));
/* Ignore errors, there's nothing we can do */
(void)ret;
/*
* Reading one completion at a time makes nested event loop re-entrancy
* simple. Change this loop to get multiple completions in one go if it
* becomes a performance bottleneck.
*/
while (true) {
struct blkio_completion completion;
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
ret = blkioq_do_io(s->blkioq, &completion, 0, 1, NULL);
}
if (ret != 1) {
break;
}
BlkioCoData *cod = completion.user_data;
cod->ret = completion.ret;
aio_co_wake(cod->coroutine);
}
}
static bool blkio_completion_fd_poll(void *opaque)
{
BlockDriverState *bs = opaque;
BDRVBlkioState *s = bs->opaque;
int ret;
/* Just in case we already fetched a completion */
if (s->poll_completion.user_data != NULL) {
return true;
}
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
ret = blkioq_do_io(s->blkioq, &s->poll_completion, 0, 1, NULL);
}
return ret == 1;
}
static void blkio_completion_fd_poll_ready(void *opaque)
{
blkio_completion_fd_read(opaque);
}
static void blkio_attach_aio_context(BlockDriverState *bs,
AioContext *new_context)
{
BDRVBlkioState *s = bs->opaque;
aio_set_fd_handler(new_context, s->completion_fd,
blkio_completion_fd_read, NULL,
blkio_completion_fd_poll,
blkio_completion_fd_poll_ready, bs);
}
static void blkio_detach_aio_context(BlockDriverState *bs)
{
BDRVBlkioState *s = bs->opaque;
aio_set_fd_handler(bdrv_get_aio_context(bs), s->completion_fd, NULL, NULL,
NULL, NULL, NULL);
}
/*
* Called by blk_io_unplug() or immediately if not plugged. Called without
* blkio_lock.
*/
static void blkio_unplug_fn(void *opaque)
{
BDRVBlkioState *s = opaque;
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
blkioq_do_io(s->blkioq, NULL, 0, 0, NULL);
}
}
/*
* Schedule I/O submission after enqueuing a new request. Called without
* blkio_lock.
*/
static void blkio_submit_io(BlockDriverState *bs)
{
BDRVBlkioState *s = bs->opaque;
blk_io_plug_call(blkio_unplug_fn, s);
}
static int coroutine_fn
blkio_co_pdiscard(BlockDriverState *bs, int64_t offset, int64_t bytes)
{
BDRVBlkioState *s = bs->opaque;
BlkioCoData cod = {
.coroutine = qemu_coroutine_self(),
};
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
blkioq_discard(s->blkioq, offset, bytes, &cod, 0);
}
blkio_submit_io(bs);
qemu_coroutine_yield();
return cod.ret;
}
static int coroutine_fn
blkio_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes,
QEMUIOVector *qiov, BdrvRequestFlags flags)
{
BlkioCoData cod = {
.coroutine = qemu_coroutine_self(),
};
BDRVBlkioState *s = bs->opaque;
bool use_bounce_buffer =
s->needs_mem_regions && !(flags & BDRV_REQ_REGISTERED_BUF);
BlkioBounceBuf bounce;
struct iovec *iov = qiov->iov;
int iovcnt = qiov->niov;
if (use_bounce_buffer) {
int ret = blkio_alloc_bounce_buffer(s, &bounce, bytes);
if (ret < 0) {
return ret;
}
iov = &bounce.buf;
iovcnt = 1;
}
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
blkioq_readv(s->blkioq, offset, iov, iovcnt, &cod, 0);
}
blkio_submit_io(bs);
qemu_coroutine_yield();
if (use_bounce_buffer) {
if (cod.ret == 0) {
qemu_iovec_from_buf(qiov, 0,
bounce.buf.iov_base,
bounce.buf.iov_len);
}
blkio_free_bounce_buffer(s, &bounce);
}
return cod.ret;
}
static int coroutine_fn blkio_co_pwritev(BlockDriverState *bs, int64_t offset,
int64_t bytes, QEMUIOVector *qiov, BdrvRequestFlags flags)
{
uint32_t blkio_flags = (flags & BDRV_REQ_FUA) ? BLKIO_REQ_FUA : 0;
BlkioCoData cod = {
.coroutine = qemu_coroutine_self(),
};
BDRVBlkioState *s = bs->opaque;
bool use_bounce_buffer =
s->needs_mem_regions && !(flags & BDRV_REQ_REGISTERED_BUF);
BlkioBounceBuf bounce;
struct iovec *iov = qiov->iov;
int iovcnt = qiov->niov;
if (use_bounce_buffer) {
int ret = blkio_alloc_bounce_buffer(s, &bounce, bytes);
if (ret < 0) {
return ret;
}
qemu_iovec_to_buf(qiov, 0, bounce.buf.iov_base, bytes);
iov = &bounce.buf;
iovcnt = 1;
}
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
blkioq_writev(s->blkioq, offset, iov, iovcnt, &cod, blkio_flags);
}
blkio_submit_io(bs);
qemu_coroutine_yield();
if (use_bounce_buffer) {
blkio_free_bounce_buffer(s, &bounce);
}
return cod.ret;
}
static int coroutine_fn blkio_co_flush(BlockDriverState *bs)
{
BDRVBlkioState *s = bs->opaque;
BlkioCoData cod = {
.coroutine = qemu_coroutine_self(),
};
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
blkioq_flush(s->blkioq, &cod, 0);
}
blkio_submit_io(bs);
qemu_coroutine_yield();
return cod.ret;
}
static int coroutine_fn blkio_co_pwrite_zeroes(BlockDriverState *bs,
int64_t offset, int64_t bytes, BdrvRequestFlags flags)
{
BDRVBlkioState *s = bs->opaque;
BlkioCoData cod = {
.coroutine = qemu_coroutine_self(),
};
uint32_t blkio_flags = 0;
if (flags & BDRV_REQ_FUA) {
blkio_flags |= BLKIO_REQ_FUA;
}
if (!(flags & BDRV_REQ_MAY_UNMAP)) {
blkio_flags |= BLKIO_REQ_NO_UNMAP;
}
if (flags & BDRV_REQ_NO_FALLBACK) {
blkio_flags |= BLKIO_REQ_NO_FALLBACK;
}
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
blkioq_write_zeroes(s->blkioq, offset, bytes, &cod, blkio_flags);
}
blkio_submit_io(bs);
qemu_coroutine_yield();
return cod.ret;
}
typedef enum {
BMRR_OK,
BMRR_SKIP,
BMRR_FAIL,
} BlkioMemRegionResult;
/*
* Produce a struct blkio_mem_region for a given address and size.
*
* This function produces identical results when called multiple times with the
* same arguments. This property is necessary because blkio_unmap_mem_region()
* must receive the same struct blkio_mem_region field values that were passed
* to blkio_map_mem_region().
*/
static BlkioMemRegionResult
blkio_mem_region_from_host(BlockDriverState *bs,
void *host, size_t size,
struct blkio_mem_region *region,
Error **errp)
{
BDRVBlkioState *s = bs->opaque;
int fd = -1;
ram_addr_t fd_offset = 0;
if (((uintptr_t)host | size) % s->mem_region_alignment) {
error_setg(errp, "unaligned buf %p with size %zu", host, size);
return BMRR_FAIL;
}
/* Attempt to find the fd for the underlying memory */
if (s->needs_mem_region_fd) {
RAMBlock *ram_block;
RAMBlock *end_block;
ram_addr_t offset;
/*
* bdrv_register_buf() is called with the BQL held so mr lives at least
* until this function returns.
*/
ram_block = qemu_ram_block_from_host(host, false, &fd_offset);
if (ram_block) {
fd = qemu_ram_get_fd(ram_block);
}
if (fd == -1) {
/*
* Ideally every RAMBlock would have an fd. pc-bios and other
* things don't. Luckily they are usually not I/O buffers and we
* can just ignore them.
*/
return BMRR_SKIP;
}
/* Make sure the fd covers the entire range */
end_block = qemu_ram_block_from_host(host + size - 1, false, &offset);
if (ram_block != end_block) {
error_setg(errp, "registered buffer at %p with size %zu extends "
"beyond RAMBlock", host, size);
return BMRR_FAIL;
}
}
*region = (struct blkio_mem_region){
.addr = host,
.len = size,
.fd = fd,
.fd_offset = fd_offset,
};
return BMRR_OK;
}
static bool blkio_register_buf(BlockDriverState *bs, void *host, size_t size,
Error **errp)
{
BDRVBlkioState *s = bs->opaque;
struct blkio_mem_region region;
BlkioMemRegionResult region_result;
int ret;
/*
* Mapping memory regions conflicts with RAM discard (virtio-mem) when
* there is pinning, so only do it when necessary.
*/
if (!s->needs_mem_regions && s->may_pin_mem_regions) {
return true;
}
region_result = blkio_mem_region_from_host(bs, host, size, &region, errp);
if (region_result == BMRR_SKIP) {
return true;
} else if (region_result != BMRR_OK) {
return false;
}
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
ret = blkio_map_mem_region(s->blkio, &region);
}
if (ret < 0) {
error_setg(errp, "Failed to add blkio mem region %p with size %zu: %s",
host, size, blkio_get_error_msg());
return false;
}
return true;
}
static void blkio_unregister_buf(BlockDriverState *bs, void *host, size_t size)
{
BDRVBlkioState *s = bs->opaque;
struct blkio_mem_region region;
/* See blkio_register_buf() */
if (!s->needs_mem_regions && s->may_pin_mem_regions) {
return;
}
if (blkio_mem_region_from_host(bs, host, size, &region, NULL) != BMRR_OK) {
return;
}
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
blkio_unmap_mem_region(s->blkio, &region);
}
}
static int blkio_io_uring_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
const char *filename = qdict_get_str(options, "filename");
BDRVBlkioState *s = bs->opaque;
int ret;
ret = blkio_set_str(s->blkio, "path", filename);
qdict_del(options, "filename");
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to set path: %s",
blkio_get_error_msg());
return ret;
}
if (flags & BDRV_O_NOCACHE) {
ret = blkio_set_bool(s->blkio, "direct", true);
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to set direct: %s",
blkio_get_error_msg());
return ret;
}
}
return 0;
}
static int blkio_nvme_io_uring(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
const char *path = qdict_get_try_str(options, "path");
BDRVBlkioState *s = bs->opaque;
int ret;
if (!path) {
error_setg(errp, "missing 'path' option");
return -EINVAL;
}
ret = blkio_set_str(s->blkio, "path", path);
qdict_del(options, "path");
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to set path: %s",
blkio_get_error_msg());
return ret;
}
if (!(flags & BDRV_O_NOCACHE)) {
error_setg(errp, "cache.direct=off is not supported");
return -EINVAL;
}
return 0;
}
static int blkio_virtio_blk_common_open(BlockDriverState *bs,
QDict *options, int flags, Error **errp)
{
const char *path = qdict_get_try_str(options, "path");
BDRVBlkioState *s = bs->opaque;
bool fd_supported = false;
int fd, ret;
if (!path) {
error_setg(errp, "missing 'path' option");
return -EINVAL;
}
if (!(flags & BDRV_O_NOCACHE)) {
error_setg(errp, "cache.direct=off is not supported");
return -EINVAL;
}
if (blkio_get_int(s->blkio, "fd", &fd) == 0) {
fd_supported = true;
}
/*
* If the libblkio driver supports fd passing, let's always use qemu_open()
* to open the `path`, so we can handle fd passing from the management
* layer through the "/dev/fdset/N" special path.
*/
if (fd_supported) {
int open_flags;
if (flags & BDRV_O_RDWR) {
open_flags = O_RDWR;
} else {
open_flags = O_RDONLY;
}
fd = qemu_open(path, open_flags, errp);
if (fd < 0) {
return -EINVAL;
}
ret = blkio_set_int(s->blkio, "fd", fd);
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to set fd: %s",
blkio_get_error_msg());
qemu_close(fd);
return ret;
}
} else {
ret = blkio_set_str(s->blkio, "path", path);
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to set path: %s",
blkio_get_error_msg());
return ret;
}
}
qdict_del(options, "path");
return 0;
}
static int blkio_file_open(BlockDriverState *bs, QDict *options, int flags,
Error **errp)
{
const char *blkio_driver = bs->drv->protocol_name;
BDRVBlkioState *s = bs->opaque;
int ret;
ret = blkio_create(blkio_driver, &s->blkio);
if (ret < 0) {
error_setg_errno(errp, -ret, "blkio_create failed: %s",
blkio_get_error_msg());
return ret;
}
if (strcmp(blkio_driver, DRIVER_IO_URING) == 0) {
ret = blkio_io_uring_open(bs, options, flags, errp);
} else if (strcmp(blkio_driver, DRIVER_NVME_IO_URING) == 0) {
ret = blkio_nvme_io_uring(bs, options, flags, errp);
} else if (strcmp(blkio_driver, DRIVER_VIRTIO_BLK_VFIO_PCI) == 0) {
ret = blkio_virtio_blk_common_open(bs, options, flags, errp);
} else if (strcmp(blkio_driver, DRIVER_VIRTIO_BLK_VHOST_USER) == 0) {
ret = blkio_virtio_blk_common_open(bs, options, flags, errp);
} else if (strcmp(blkio_driver, DRIVER_VIRTIO_BLK_VHOST_VDPA) == 0) {
ret = blkio_virtio_blk_common_open(bs, options, flags, errp);
} else {
g_assert_not_reached();
}
if (ret < 0) {
blkio_destroy(&s->blkio);
return ret;
}
if (!(flags & BDRV_O_RDWR)) {
ret = blkio_set_bool(s->blkio, "read-only", true);
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to set read-only: %s",
blkio_get_error_msg());
blkio_destroy(&s->blkio);
return ret;
}
}
ret = blkio_connect(s->blkio);
if (ret < 0) {
error_setg_errno(errp, -ret, "blkio_connect failed: %s",
blkio_get_error_msg());
blkio_destroy(&s->blkio);
return ret;
}
ret = blkio_get_bool(s->blkio,
"needs-mem-regions",
&s->needs_mem_regions);
if (ret < 0) {
error_setg_errno(errp, -ret,
"failed to get needs-mem-regions: %s",
blkio_get_error_msg());
blkio_destroy(&s->blkio);
return ret;
}
ret = blkio_get_bool(s->blkio,
"needs-mem-region-fd",
&s->needs_mem_region_fd);
if (ret < 0) {
error_setg_errno(errp, -ret,
"failed to get needs-mem-region-fd: %s",
blkio_get_error_msg());
blkio_destroy(&s->blkio);
return ret;
}
ret = blkio_get_uint64(s->blkio,
"mem-region-alignment",
&s->mem_region_alignment);
if (ret < 0) {
error_setg_errno(errp, -ret,
"failed to get mem-region-alignment: %s",
blkio_get_error_msg());
blkio_destroy(&s->blkio);
return ret;
}
ret = blkio_get_bool(s->blkio,
"may-pin-mem-regions",
&s->may_pin_mem_regions);
if (ret < 0) {
/* Be conservative (assume pinning) if the property is not supported */
s->may_pin_mem_regions = s->needs_mem_regions;
}
/*
* Notify if libblkio drivers pin memory and prevent features like
* virtio-mem from working.
*/
if (s->may_pin_mem_regions) {
ret = ram_block_discard_disable(true);
if (ret < 0) {
error_setg_errno(errp, -ret, "ram_block_discard_disable() failed");
blkio_destroy(&s->blkio);
return ret;
}
}
ret = blkio_start(s->blkio);
if (ret < 0) {
error_setg_errno(errp, -ret, "blkio_start failed: %s",
blkio_get_error_msg());
blkio_destroy(&s->blkio);
if (s->may_pin_mem_regions) {
ram_block_discard_disable(false);
}
return ret;
}
bs->supported_write_flags = BDRV_REQ_FUA | BDRV_REQ_REGISTERED_BUF;
bs->supported_zero_flags = BDRV_REQ_FUA | BDRV_REQ_MAY_UNMAP |
BDRV_REQ_NO_FALLBACK;
qemu_mutex_init(&s->blkio_lock);
qemu_co_mutex_init(&s->bounce_lock);
qemu_co_queue_init(&s->bounce_available);
QLIST_INIT(&s->bounce_bufs);
s->blkioq = blkio_get_queue(s->blkio, 0);
s->completion_fd = blkioq_get_completion_fd(s->blkioq);
blkio_attach_aio_context(bs, bdrv_get_aio_context(bs));
return 0;
}
static void blkio_close(BlockDriverState *bs)
{
BDRVBlkioState *s = bs->opaque;
/* There is no destroy() API for s->bounce_lock */
qemu_mutex_destroy(&s->blkio_lock);
blkio_detach_aio_context(bs);
blkio_destroy(&s->blkio);
if (s->may_pin_mem_regions) {
ram_block_discard_disable(false);
}
}
static int64_t coroutine_fn blkio_co_getlength(BlockDriverState *bs)
{
BDRVBlkioState *s = bs->opaque;
uint64_t capacity;
int ret;
WITH_QEMU_LOCK_GUARD(&s->blkio_lock) {
ret = blkio_get_uint64(s->blkio, "capacity", &capacity);
}
if (ret < 0) {
return -ret;
}
return capacity;
}
static int coroutine_fn blkio_truncate(BlockDriverState *bs, int64_t offset,
bool exact, PreallocMode prealloc,
BdrvRequestFlags flags, Error **errp)
{
int64_t current_length;
if (prealloc != PREALLOC_MODE_OFF) {
error_setg(errp, "Unsupported preallocation mode '%s'",
PreallocMode_str(prealloc));
return -ENOTSUP;
}
current_length = blkio_co_getlength(bs);
if (offset > current_length) {
error_setg(errp, "Cannot grow device");
return -EINVAL;
} else if (exact && offset != current_length) {
error_setg(errp, "Cannot resize device");
return -ENOTSUP;
}
return 0;
}
static int coroutine_fn
blkio_co_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
{
return 0;
}
static void blkio_refresh_limits(BlockDriverState *bs, Error **errp)
{
BDRVBlkioState *s = bs->opaque;
QEMU_LOCK_GUARD(&s->blkio_lock);
int value;
int ret;
ret = blkio_get_int(s->blkio, "request-alignment", &value);
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to get \"request-alignment\": %s",
blkio_get_error_msg());
return;
}
bs->bl.request_alignment = value;
if (bs->bl.request_alignment < 1 ||
bs->bl.request_alignment >= INT_MAX ||
!is_power_of_2(bs->bl.request_alignment)) {
error_setg(errp, "invalid \"request-alignment\" value %" PRIu32 ", "
"must be a power of 2 less than INT_MAX",
bs->bl.request_alignment);
return;
}
ret = blkio_get_int(s->blkio, "optimal-io-size", &value);
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to get \"optimal-io-size\": %s",
blkio_get_error_msg());
return;
}
bs->bl.opt_transfer = value;
if (bs->bl.opt_transfer > INT_MAX ||
(bs->bl.opt_transfer % bs->bl.request_alignment)) {
error_setg(errp, "invalid \"optimal-io-size\" value %" PRIu32 ", must "
"be a multiple of %" PRIu32, bs->bl.opt_transfer,
bs->bl.request_alignment);
return;
}
ret = blkio_get_int(s->blkio, "max-transfer", &value);
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to get \"max-transfer\": %s",
blkio_get_error_msg());
return;
}
bs->bl.max_transfer = value;
if ((bs->bl.max_transfer % bs->bl.request_alignment) ||
(bs->bl.opt_transfer && (bs->bl.max_transfer % bs->bl.opt_transfer))) {
error_setg(errp, "invalid \"max-transfer\" value %" PRIu32 ", must be "
"a multiple of %" PRIu32 " and %" PRIu32 " (if non-zero)",
bs->bl.max_transfer, bs->bl.request_alignment,
bs->bl.opt_transfer);
return;
}
ret = blkio_get_int(s->blkio, "buf-alignment", &value);
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to get \"buf-alignment\": %s",
blkio_get_error_msg());
return;
}
if (value < 1) {
error_setg(errp, "invalid \"buf-alignment\" value %d, must be "
"positive", value);
return;
}
bs->bl.min_mem_alignment = value;
ret = blkio_get_int(s->blkio, "optimal-buf-alignment", &value);
if (ret < 0) {
error_setg_errno(errp, -ret,
"failed to get \"optimal-buf-alignment\": %s",
blkio_get_error_msg());
return;
}
if (value < 1) {
error_setg(errp, "invalid \"optimal-buf-alignment\" value %d, "
"must be positive", value);
return;
}
bs->bl.opt_mem_alignment = value;
ret = blkio_get_int(s->blkio, "max-segments", &value);
if (ret < 0) {
error_setg_errno(errp, -ret, "failed to get \"max-segments\": %s",
blkio_get_error_msg());
return;
}
if (value < 1) {
error_setg(errp, "invalid \"max-segments\" value %d, must be positive",
value);
return;
}
bs->bl.max_iov = value;
}
/*
* TODO
* Missing libblkio APIs:
* - block_status
* - co_invalidate_cache
*
* Out of scope?
* - create
* - truncate
*/
#define BLKIO_DRIVER(name, ...) \
{ \
.format_name = name, \
.protocol_name = name, \
.instance_size = sizeof(BDRVBlkioState), \
.bdrv_file_open = blkio_file_open, \
.bdrv_close = blkio_close, \
.bdrv_co_getlength = blkio_co_getlength, \
.bdrv_co_truncate = blkio_truncate, \
.bdrv_co_get_info = blkio_co_get_info, \
.bdrv_attach_aio_context = blkio_attach_aio_context, \
.bdrv_detach_aio_context = blkio_detach_aio_context, \
.bdrv_co_pdiscard = blkio_co_pdiscard, \
.bdrv_co_preadv = blkio_co_preadv, \
.bdrv_co_pwritev = blkio_co_pwritev, \
.bdrv_co_flush_to_disk = blkio_co_flush, \
.bdrv_co_pwrite_zeroes = blkio_co_pwrite_zeroes, \
.bdrv_refresh_limits = blkio_refresh_limits, \
.bdrv_register_buf = blkio_register_buf, \
.bdrv_unregister_buf = blkio_unregister_buf, \
__VA_ARGS__ \
}
static BlockDriver bdrv_io_uring = BLKIO_DRIVER(
DRIVER_IO_URING,
.bdrv_needs_filename = true,
);
static BlockDriver bdrv_nvme_io_uring = BLKIO_DRIVER(
DRIVER_NVME_IO_URING,
);
static BlockDriver bdrv_virtio_blk_vfio_pci = BLKIO_DRIVER(
DRIVER_VIRTIO_BLK_VFIO_PCI
);
static BlockDriver bdrv_virtio_blk_vhost_user = BLKIO_DRIVER(
DRIVER_VIRTIO_BLK_VHOST_USER
);
static BlockDriver bdrv_virtio_blk_vhost_vdpa = BLKIO_DRIVER(
DRIVER_VIRTIO_BLK_VHOST_VDPA
);
static void bdrv_blkio_init(void)
{
bdrv_register(&bdrv_io_uring);
bdrv_register(&bdrv_nvme_io_uring);
bdrv_register(&bdrv_virtio_blk_vfio_pci);
bdrv_register(&bdrv_virtio_blk_vhost_user);
bdrv_register(&bdrv_virtio_blk_vhost_vdpa);
}
block_init(bdrv_blkio_init);
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