diff --git a/block/blkio.c b/block/blkio.c index b0cfd74b36..82f26eedd2 100644 --- a/block/blkio.c +++ b/block/blkio.c @@ -11,9 +11,13 @@ #include "qemu/osdep.h" #include #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 "exec/memory.h" /* for ram_block_discard_disable() */ /* * Keep the QEMU BlockDriver names identical to the libblkio driver names. @@ -73,6 +77,12 @@ typedef struct { /* 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 */ @@ -347,7 +357,8 @@ blkio_co_preadv(BlockDriverState *bs, int64_t offset, int64_t bytes, .coroutine = qemu_coroutine_self(), }; BDRVBlkioState *s = bs->opaque; - bool use_bounce_buffer = s->needs_mem_regions; + bool use_bounce_buffer = + s->needs_mem_regions && !(flags & BDRV_REQ_REGISTERED_BUF); BlkioBounceBuf bounce; struct iovec *iov = qiov->iov; int iovcnt = qiov->niov; @@ -390,7 +401,8 @@ static int coroutine_fn blkio_co_pwritev(BlockDriverState *bs, int64_t offset, .coroutine = qemu_coroutine_self(), }; BDRVBlkioState *s = bs->opaque; - bool use_bounce_buffer = s->needs_mem_regions; + bool use_bounce_buffer = + s->needs_mem_regions && !(flags & BDRV_REQ_REGISTERED_BUF); BlkioBounceBuf bounce; struct iovec *iov = qiov->iov; int iovcnt = qiov->niov; @@ -473,6 +485,130 @@ static void blkio_io_unplug(BlockDriverState *bs) } } +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, ®ion, 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, ®ion); + } + + 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, ®ion, NULL) != BMRR_OK) { + return; + } + + WITH_QEMU_LOCK_GUARD(&s->blkio_lock) { + blkio_unmap_mem_region(s->blkio, ®ion); + } +} + static int blkio_io_uring_open(BlockDriverState *bs, QDict *options, int flags, Error **errp) { @@ -609,6 +745,17 @@ static int blkio_file_open(BlockDriverState *bs, QDict *options, int flags, 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); @@ -620,15 +767,39 @@ static int blkio_file_open(BlockDriverState *bs, QDict *options, int flags, 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; + 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; @@ -652,6 +823,10 @@ static void blkio_close(BlockDriverState *bs) 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 blkio_getlength(BlockDriverState *bs) @@ -799,6 +974,8 @@ static void blkio_refresh_limits(BlockDriverState *bs, Error **errp) .bdrv_co_pwrite_zeroes = blkio_co_pwrite_zeroes, \ .bdrv_io_unplug = blkio_io_unplug, \ .bdrv_refresh_limits = blkio_refresh_limits, \ + .bdrv_register_buf = blkio_register_buf, \ + .bdrv_unregister_buf = blkio_unregister_buf, \ __VA_ARGS__ \ }