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SUSE:SLE-12-SP4:Update
qemu.12242
0077-hostmem-file-add-align-option.patch
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File 0077-hostmem-file-add-align-option.patch of Package qemu.12242
From 1f26c54b7e1014a3da9e023e38e9450ebb4404fd Mon Sep 17 00:00:00 2001 From: Haozhong Zhang <haozhong.zhang@intel.com> Date: Mon, 11 Dec 2017 15:28:04 +0800 Subject: [PATCH] hostmem-file: add "align" option When mmap(2) the backend files, QEMU uses the host page size (getpagesize(2)) by default as the alignment of mapping address. However, some backends may require alignments different than the page size. For example, mmap a device DAX (e.g., /dev/dax0.0) on Linux kernel 4.13 to an address, which is 4K-aligned but not 2M-aligned, fails with a kernel message like [617494.969768] dax dax0.0: qemu-system-x86: dax_mmap: fail, unaligned vma (0x7fa37c579000 - 0x7fa43c579000, 0x1fffff) Because there is no common approach to get such alignment requirement, we add the 'align' option to 'memory-backend-file', so that users or management utils, which have enough knowledge about the backend, can specify a proper alignment via this option. Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com> Message-Id: <20171211072806.2812-2-haozhong.zhang@intel.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> [ehabkost: fixed typo, fixed error_setg() format string] Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> (cherry picked from commit 983768431676f9ab8599a0b4813e1ca17af70838) [BR: FATE#325135] Signed-off-by: Bruce Rogers <brogers@suse.com> --- backends/hostmem-file.c | 41 ++++++++++++++++++++++++++++++++++++++++- docs/nvdimm.txt | 16 ++++++++++++++++ exec.c | 8 +++++++- include/exec/memory.h | 3 +++ memory.c | 2 ++ numa.c | 2 +- qemu-options.hx | 9 ++++++++- 7 files changed, 77 insertions(+), 4 deletions(-) diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index e44c319915..e319ec1ad8 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -34,6 +34,7 @@ struct HostMemoryBackendFile { bool share; bool discard_data; char *mem_path; + uint64_t align; }; static void @@ -58,7 +59,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) path = object_get_canonical_path(OBJECT(backend)); memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), path, - backend->size, fb->share, + backend->size, fb->align, fb->share, fb->mem_path, errp); g_free(path); } @@ -115,6 +116,40 @@ static void file_memory_backend_set_discard_data(Object *o, bool value, MEMORY_BACKEND_FILE(o)->discard_data = value; } +static void file_memory_backend_get_align(Object *o, Visitor *v, + const char *name, void *opaque, + Error **errp) +{ + HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o); + uint64_t val = fb->align; + + visit_type_size(v, name, &val, errp); +} + +static void file_memory_backend_set_align(Object *o, Visitor *v, + const char *name, void *opaque, + Error **errp) +{ + HostMemoryBackend *backend = MEMORY_BACKEND(o); + HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(o); + Error *local_err = NULL; + uint64_t val; + + if (host_memory_backend_mr_inited(backend)) { + error_setg(&local_err, "cannot change property value"); + goto out; + } + + visit_type_size(v, name, &val, &local_err); + if (local_err) { + goto out; + } + fb->align = val; + + out: + error_propagate(errp, local_err); +} + static void file_backend_unparent(Object *obj) { HostMemoryBackend *backend = MEMORY_BACKEND(obj); @@ -145,6 +180,10 @@ file_backend_class_init(ObjectClass *oc, void *data) object_class_property_add_str(oc, "mem-path", get_mem_path, set_mem_path, &error_abort); + object_class_property_add(oc, "align", "int", + file_memory_backend_get_align, + file_memory_backend_set_align, + NULL, NULL, &error_abort); } static void file_backend_instance_finalize(Object *o) diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt index 2d9f8c0e8c..21249dd062 100644 --- a/docs/nvdimm.txt +++ b/docs/nvdimm.txt @@ -122,3 +122,19 @@ Note: M >= size of RAM devices + size of statically plugged vNVDIMM devices + size of hotplugged vNVDIMM devices + +Alignment +--------- + +QEMU uses mmap(2) to maps vNVDIMM backends and aligns the mapping +address to the page size (getpagesize(2)) by default. However, some +types of backends may require an alignment different than the page +size. In that case, QEMU v2.12.0 and later provide 'align' option to +memory-backend-file to allow users to specify the proper alignment. + +For example, device dax require the 2 MB alignment, so we can use +following QEMU command line options to use it (/dev/dax0.0) as the +backend of vNVDIMM: + + -object memory-backend-file,id=mem1,share=on,mem-path=/dev/dax0.0,size=4G,align=2M + -device nvdimm,id=nvdimm1,memdev=mem1 diff --git a/exec.c b/exec.c index 7496b39f3b..bcb7776097 100644 --- a/exec.c +++ b/exec.c @@ -1601,7 +1601,13 @@ static void *file_ram_alloc(RAMBlock *block, void *area; block->page_size = qemu_fd_getpagesize(fd); - block->mr->align = block->page_size; + if (block->mr->align % block->page_size) { + error_setg(errp, "alignment 0x%" PRIx64 + " must be multiples of page size 0x%zx", + block->mr->align, block->page_size); + return NULL; + } + block->mr->align = MAX(block->page_size, block->mr->align); #if defined(__s390x__) if (kvm_enabled()) { block->mr->align = MAX(block->mr->align, QEMU_VMALLOC_ALIGN); diff --git a/include/exec/memory.h b/include/exec/memory.h index e7fdb1b79a..5b51badf6a 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -485,6 +485,8 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr, * @name: Region name, becomes part of RAMBlock name used in migration stream * must be unique within any device * @size: size of the region. + * @align: alignment of the region base address; if 0, the default alignment + * (getpagesize()) will be used. * @share: %true if memory must be mmaped with the MAP_SHARED flag * @path: the path in which to allocate the RAM. * @errp: pointer to Error*, to store an error if it happens. @@ -496,6 +498,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, struct Object *owner, const char *name, uint64_t size, + uint64_t align, bool share, const char *path, Error **errp); diff --git a/memory.c b/memory.c index b2e23c31f4..e3ff978031 100644 --- a/memory.c +++ b/memory.c @@ -1541,6 +1541,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, struct Object *owner, const char *name, uint64_t size, + uint64_t align, bool share, const char *path, Error **errp) @@ -1549,6 +1550,7 @@ void memory_region_init_ram_from_file(MemoryRegion *mr, mr->ram = true; mr->terminates = true; mr->destructor = memory_region_destructor_ram; + mr->align = align; mr->ram_block = qemu_ram_alloc_from_file(size, mr, share, path, errp); mr->dirty_log_mask = tcg_enabled() ? (1 << DIRTY_MEMORY_CODE) : 0; } diff --git a/numa.c b/numa.c index 7151b24d1c..b0fe22a60c 100644 --- a/numa.c +++ b/numa.c @@ -551,7 +551,7 @@ static void allocate_system_memory_nonnuma(MemoryRegion *mr, Object *owner, if (mem_path) { #ifdef __linux__ Error *err = NULL; - memory_region_init_ram_from_file(mr, owner, name, ram_size, false, + memory_region_init_ram_from_file(mr, owner, name, ram_size, 0, false, mem_path, &err); if (err) { error_report_err(err); diff --git a/qemu-options.hx b/qemu-options.hx index e3bf04c83d..6ba454a531 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -4197,7 +4197,7 @@ property must be set. These objects are placed in the @table @option -@item -object memory-backend-file,id=@var{id},size=@var{size},mem-path=@var{dir},share=@var{on|off},discard-data=@var{on|off} +@item -object memory-backend-file,id=@var{id},size=@var{size},mem-path=@var{dir},share=@var{on|off},discard-data=@var{on|off},align=@var{align} Creates a memory file backend object, which can be used to back the guest RAM with huge pages. The @option{id} parameter is a @@ -4216,6 +4216,13 @@ that @option{discard-data} is only an optimization, and QEMU might not discard file contents if it aborts unexpectedly or is terminated using SIGKILL. +The @option{align} option specifies the base address alignment when +QEMU mmap(2) @option{mem-path}, and accepts common suffixes, eg +@option{2M}. Some backend store specified by @option{mem-path} +requires an alignment different than the default one used by QEMU, eg +the device DAX /dev/dax0.0 requires 2M alignment rather than 4K. In +such cases, users can specify the required alignment via this option. + @item -object rng-random,id=@var{id},filename=@var{/dev/random} Creates a random number generator backend which obtains entropy from
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