From nobody Tue Feb 10 15:29:35 2026 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) client-ip=208.118.235.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 208.118.235.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (208.118.235.17 [208.118.235.17]) by mx.zohomail.com with SMTPS id 1511757512820641.2668577946721; Sun, 26 Nov 2017 20:38:32 -0800 (PST) Received: from localhost ([::1]:59145 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eJBBT-0000vF-93 for importer@patchew.org; Sun, 26 Nov 2017 23:38:19 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:43879) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eJB9l-0007pM-IX for qemu-devel@nongnu.org; Sun, 26 Nov 2017 23:36:35 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eJB9g-0004wR-Q4 for qemu-devel@nongnu.org; Sun, 26 Nov 2017 23:36:33 -0500 Received: from mga06.intel.com ([134.134.136.31]:29419) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eJB9g-0004w1-Df for qemu-devel@nongnu.org; Sun, 26 Nov 2017 23:36:28 -0500 Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga104.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Nov 2017 20:36:27 -0800 Received: from hz-desktop.sh.intel.com (HELO localhost) ([10.239.159.142]) by orsmga003.jf.intel.com with ESMTP; 26 Nov 2017 20:36:24 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.44,462,1505804400"; d="scan'208";a="6602666" From: Haozhong Zhang To: qemu-devel@nongnu.org Date: Mon, 27 Nov 2017 12:35:15 +0800 Message-Id: <20171127043517.22441-2-haozhong.zhang@intel.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20171127043517.22441-1-haozhong.zhang@intel.com> References: <20171127043517.22441-1-haozhong.zhang@intel.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 134.134.136.31 Subject: [Qemu-devel] [PATCH v3 1/3] hostmem-file: add "align" option X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Haozhong Zhang , Eduardo Habkost , Peter Crosthwaite , Stefan Hajnoczi , Xiao Guangrong , Paolo Bonzini , Igor Mammedov , Dan Williams , Richard Henderson Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail: RSF_0 Z_629925259 SPT_0 Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 --- backends/hostmem-file.c | 41 ++++++++++++++++++++++++++++++++++++++++- docs/nvdimm.txt | 16 ++++++++++++++++ exec.c | 8 +++++++- include/exec/memory.h | 3 +++ memory.c | 2 ++ numa.c | 2 +- 6 files changed, 69 insertions(+), 3 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; }; =20 static void @@ -58,7 +59,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Err= or **errp) path =3D 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(Objec= t *o, bool value, MEMORY_BACKEND_FILE(o)->discard_data =3D value; } =20 +static void file_memory_backend_get_align(Object *o, Visitor *v, + const char *name, void *opaque, + Error **errp) +{ + HostMemoryBackendFile *fb =3D MEMORY_BACKEND_FILE(o); + uint64_t val =3D 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 =3D MEMORY_BACKEND(o); + HostMemoryBackendFile *fb =3D MEMORY_BACKEND_FILE(o); + Error *local_err =3D 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 =3D val; + + out: + error_propagate(errp, local_err); +} + static void file_backend_unparent(Object *obj) { HostMemoryBackend *backend =3D 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); } =20 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 >=3D 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=3Dmem1,share=3Don,mem-path=3D/dev/dax0.0,s= ize=3D4G,align=3D2M + -device nvdimm,id=3Dnvdimm1,memdev=3Dmem1 diff --git a/exec.c b/exec.c index 03238a3449..90440efecd 100644 --- a/exec.c +++ b/exec.c @@ -1600,7 +1600,13 @@ static void *file_ram_alloc(RAMBlock *block, void *area; =20 block->page_size =3D qemu_fd_getpagesize(fd); - block->mr->align =3D block->page_size; + if (block->mr->align % block->page_size) { + error_setg(errp, "aligment 0x%" PRIx64 + " must be multiples of page size 0x%" PRIx64, + block->mr->align, block->page_size); + return NULL; + } + block->mr->align =3D MAX(block->page_size, block->mr->align); #if defined(__s390x__) if (kvm_enabled()) { block->mr->align =3D MAX(block->mr->align, QEMU_VMALLOC_ALIGN); diff --git a/include/exec/memory.h b/include/exec/memory.h index 5ed4042f87..a1be8b06d3 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -465,6 +465,8 @@ void memory_region_init_resizeable_ram(MemoryRegion *mr, * @name: Region name, becomes part of RAMBlock name used in migration str= eam * must be unique within any device * @size: size of the region. + * @align: alignment of the region base address; if 0, the default alignme= nt + * (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. @@ -476,6 +478,7 @@ 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 e26e5a3b1d..2c80656e39 100644 --- a/memory.c +++ b/memory.c @@ -1570,6 +1570,7 @@ void memory_region_init_ram_from_file(MemoryRegion *m= r, struct Object *owner, const char *name, uint64_t size, + uint64_t align, bool share, const char *path, Error **errp) @@ -1578,6 +1579,7 @@ void memory_region_init_ram_from_file(MemoryRegion *m= r, mr->ram =3D true; mr->terminates =3D true; mr->destructor =3D memory_region_destructor_ram; + mr->align =3D align; mr->ram_block =3D qemu_ram_alloc_from_file(size, mr, share, path, errp= ); mr->dirty_log_mask =3D 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 =3D 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, fal= se, mem_path, &err); if (err) { error_report_err(err); --=20 2.14.1