From patchwork Mon Nov 5 08:29:47 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Zhang, Yi" X-Patchwork-Id: 10667579 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 9683813A4 for ; Mon, 5 Nov 2018 08:32:17 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 864C229320 for ; Mon, 5 Nov 2018 08:32:17 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 7A5CF29329; Mon, 5 Nov 2018 08:32:17 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id C023129320 for ; Mon, 5 Nov 2018 08:32:16 +0000 (UTC) Received: from localhost ([::1]:33803 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gJaIy-0002aM-1n for patchwork-qemu-devel@patchwork.kernel.org; Mon, 05 Nov 2018 03:32:16 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:44786) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gJaHL-0000mB-3C for qemu-devel@nongnu.org; Mon, 05 Nov 2018 03:30:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gJaHG-00076d-4I for qemu-devel@nongnu.org; Mon, 05 Nov 2018 03:30:35 -0500 Received: from mga12.intel.com ([192.55.52.136]:25515) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gJaHA-0006Pg-EF for qemu-devel@nongnu.org; Mon, 05 Nov 2018 03:30:26 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 05 Nov 2018 00:30:22 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,467,1534834800"; d="scan'208";a="247044084" Received: from linux.intel.com ([10.54.29.200]) by orsmga004.jf.intel.com with ESMTP; 05 Nov 2018 00:30:22 -0800 Received: from dazhang1-ssd.sh.intel.com (unknown [10.239.48.128]) by linux.intel.com (Postfix) with ESMTP id 2518A58041B; Mon, 5 Nov 2018 00:30:19 -0800 (PST) From: Zhang Yi To: xiaoguangrong.eric@gmail.com, dan.j.williams@intel.com, stefanha@redhat.com, pbonzini@redhat.com, yu.c.zhang@linux.intel.com Date: Mon, 5 Nov 2018 16:29:47 +0800 Message-Id: X-Mailer: git-send-email 2.7.4 In-Reply-To: References: X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 192.55.52.136 Subject: [Qemu-devel] [PATCH v5 7/7] hostmem-file: add 'sync' 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: imammedo@redhat.com, Zhang Yi , qemu-devel@nongnu.org, ehabkost@redhat.com, mst@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP This option controls whether QEMU mmap(2) the memory backend file with MAP_SYNC flag, which can fully guarantee the guest write persistence to the backend, if MAP_SYNC flag is supported by the host kernel (Linux kernel 4.15 and later) and the backend is a file supporting DAX (e.g., file on ext4/xfs file system mounted with '-o dax'). It can take one of following values: - on: try to pass MAP_SYNC to mmap(2); if MAP_SYNC is not supported or 'share=off', QEMU will abort - off: never pass MAP_SYNC to mmap(2) - auto (default): if MAP_SYNC is supported and 'share=on', work as if 'sync=on'; otherwise, work as if 'sync=off' Signed-off-by: Haozhong Zhang Signed-off-by: Zhang Yi --- backends/hostmem-file.c | 39 +++++++++++++++++++++++++++++++++++++++ docs/nvdimm.txt | 20 +++++++++++++++++++- include/exec/memory.h | 8 ++++++++ qemu-options.hx | 22 +++++++++++++++++++++- 4 files changed, 87 insertions(+), 2 deletions(-) diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index 0dd7a90..73cf181 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -16,6 +16,7 @@ #include "sysemu/hostmem.h" #include "sysemu/sysemu.h" #include "qom/object_interfaces.h" +#include "qapi/qapi-visit.h" /* hostmem-file.c */ /** @@ -36,6 +37,7 @@ struct HostMemoryBackendFile { uint64_t align; bool discard_data; bool is_pmem; + OnOffAuto sync; }; static void @@ -62,6 +64,7 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) path, backend->size, fb->align, (backend->share ? RAM_SHARED : 0) | + qemu_ram_sync_flags(fb->sync) | (fb->is_pmem ? RAM_PMEM : 0), fb->mem_path, errp); g_free(path); @@ -136,6 +139,39 @@ static void file_memory_backend_set_align(Object *o, Visitor *v, error_propagate(errp, local_err); } +static void file_memory_backend_get_sync( + Object *obj, Visitor *v, const char *name, void *opaque, Error **errp) +{ + HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj); + OnOffAuto value = fb->sync; + + visit_type_OnOffAuto(v, name, &value, errp); +} + +static void file_memory_backend_set_sync( + Object *obj, Visitor *v, const char *name, void *opaque, Error **errp) +{ + HostMemoryBackend *backend = MEMORY_BACKEND(obj); + HostMemoryBackendFile *fb = MEMORY_BACKEND_FILE(obj); + Error *local_err = NULL; + OnOffAuto value; + + if (host_memory_backend_mr_inited(backend)) { + error_setg(&local_err, "cannot change property '%s' of %s", + name, object_get_typename(obj)); + goto out; + } + + visit_type_OnOffAuto(v, name, &value, &local_err); + if (local_err) { + goto out; + } + fb->sync = value; + + out: + error_propagate(errp, local_err); +} + static bool file_memory_backend_get_pmem(Object *o, Error **errp) { return MEMORY_BACKEND_FILE(o)->is_pmem; @@ -203,6 +239,9 @@ file_backend_class_init(ObjectClass *oc, void *data) object_class_property_add_bool(oc, "pmem", file_memory_backend_get_pmem, file_memory_backend_set_pmem, &error_abort); + object_class_property_add(oc, "sync", "OnOffAuto", + file_memory_backend_get_sync, file_memory_backend_set_sync, + NULL, NULL, &error_abort); } static void file_backend_instance_finalize(Object *o) diff --git a/docs/nvdimm.txt b/docs/nvdimm.txt index 5f158a6..3d89174 100644 --- a/docs/nvdimm.txt +++ b/docs/nvdimm.txt @@ -142,11 +142,29 @@ backend of vNVDIMM: Guest Data Persistence ---------------------- +vNVDIMM is designed and implemented to guarantee the guest data +persistence on the backends even on the host crash and power +failures. However, there are still some requirements and limitations +as explained below. + Though QEMU supports multiple types of vNVDIMM backends on Linux, -currently the only one that can guarantee the guest write persistence +if MAP_SYNC is not supported by the host kernel and the backends, +the only backend that can guarantee the guest write persistence is the device DAX on the real NVDIMM device (e.g., /dev/dax0.0), to which all guest access do not involve any host-side kernel cache. +mmap(2) flag MAP_SYNC is added since Linux kernel 4.15. On such +systems, QEMU can mmap(2) the backend with MAP_SYNC, which can +guarantee the guest write persistence to vNVDIMM. Besides the host +kernel support, enabling MAP_SYNC in QEMU also requires: + + - the backend is a file supporting DAX, e.g., a file on an ext4 or + xfs file system mounted with '-o dax', + + - 'sync' option of memory-backend-file is not 'off', and + + - 'share' option of memory-backend-file is 'on'. + When using other types of backends, it's suggested to set 'unarmed' option of '-device nvdimm' to 'on', which sets the unarmed flag of the guest NVDIMM region mapping structure. This unarmed flag indicates diff --git a/include/exec/memory.h b/include/exec/memory.h index c74c467..b398abb 100644 --- a/include/exec/memory.h +++ b/include/exec/memory.h @@ -26,6 +26,7 @@ #include "qom/object.h" #include "qemu/rcu.h" #include "hw/qdev-core.h" +#include "qapi/error.h" #define RAM_ADDR_INVALID (~(ram_addr_t)0) @@ -136,6 +137,13 @@ typedef struct IOMMUNotifier IOMMUNotifier; #define RAM_SYNC (RAM_SYNC_ON_OFF_AUTO_ON | RAM_SYNC_ON_OFF_AUTO_AUTO) +static inline uint64_t qemu_ram_sync_flags(OnOffAuto v) +{ + return v == ON_OFF_AUTO_OFF ? RAM_SYNC_ON_OFF_AUTO_OFF : + v == ON_OFF_AUTO_ON ? RAM_SYNC_ON_OFF_AUTO_ON : + RAM_SYNC_ON_OFF_AUTO_AUTO; +} + static inline void iommu_notifier_init(IOMMUNotifier *n, IOMMUNotify fn, IOMMUNotifierFlag flags, hwaddr start, hwaddr end, diff --git a/qemu-options.hx b/qemu-options.hx index 08f8516..77e8810 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -3928,7 +3928,7 @@ 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},merge=@var{on|off},dump=@var{on|off},prealloc=@var{on|off},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave},align=@var{align} +@item -object memory-backend-file,id=@var{id},size=@var{size},mem-path=@var{dir},share=@var{on|off},discard-data=@var{on|off},merge=@var{on|off},dump=@var{on|off},prealloc=@var{on|off},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave},align=@var{align},sync=@var{on|off|auto} Creates a memory file backend object, which can be used to back the guest RAM with huge pages. @@ -4003,6 +4003,26 @@ If @option{pmem} is set to 'on', QEMU will take necessary operations to guarantee the persistence of its own writes to @option{mem-path} (e.g. in vNVDIMM label emulation and live migration). +The @option{sync} option specifies whether QEMU mmap(2) @option{mem-path} +with MAP_SYNC flag, which can guarantee the guest write persistence to +@option{mem-path} even on the host crash and power failures. MAP_SYNC +requires supports from both the host kernel (since Linux kernel 4.15) +and @option{mem-path} (only files supporting DAX). It can take one of +following values: + +@table @option +@item @var{on} +try to pass MAP_SYNC to mmap(2); if MAP_SYNC is not supported or +@option{share}=@var{off}, QEMU will abort + +@item @var{off} +never pass MAP_SYNC to mmap(2) + +@item @var{auto} (default) +if MAP_SYNC is supported and @option{share}=@var{on}, work as if +@option{sync}=@var{on}; otherwise, work as if @option{sync}=@var{off} +@end table + @item -object memory-backend-ram,id=@var{id},merge=@var{on|off},dump=@var{on|off},share=@var{on|off},prealloc=@var{on|off},size=@var{size},host-nodes=@var{host-nodes},policy=@var{default|preferred|bind|interleave} Creates a memory backend object, which can be used to back the guest RAM.