From nobody Tue Oct 28 01:56:34 2025 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 151617712336288.41409786849579; Wed, 17 Jan 2018 00:18:43 -0800 (PST) Received: from localhost ([::1]:46606 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ebivc-0004nz-UV for importer@patchew.org; Wed, 17 Jan 2018 03:18:36 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33394) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ebitb-0003qh-Qg for qemu-devel@nongnu.org; Wed, 17 Jan 2018 03:16:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ebitX-0005x2-0P for qemu-devel@nongnu.org; Wed, 17 Jan 2018 03:16:31 -0500 Received: from mga03.intel.com ([134.134.136.65]:44721) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ebitW-0005wC-KZ for qemu-devel@nongnu.org; Wed, 17 Jan 2018 03:16:26 -0500 Received: from orsmga001.jf.intel.com ([10.7.209.18]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Jan 2018 00:16:25 -0800 Received: from hz-desktop.sh.intel.com (HELO localhost) ([10.239.13.35]) by orsmga001.jf.intel.com with ESMTP; 17 Jan 2018 00:16:22 -0800 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,372,1511856000"; d="scan'208";a="23986385" From: Haozhong Zhang To: qemu-devel@nongnu.org Date: Wed, 17 Jan 2018 16:13:23 +0800 Message-Id: <20180117081325.11924-2-haozhong.zhang@intel.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20180117081325.11924-1-haozhong.zhang@intel.com> References: <20180117081325.11924-1-haozhong.zhang@intel.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 134.134.136.65 Subject: [Qemu-devel] [PATCH v3 1/3] util/mmap-alloc: support MAP_SYNC in qemu_ram_mmap() 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 , Xiao Guangrong , mst@redhat.com, dgilbert@redhat.com, Stefan Hajnoczi , Paolo Bonzini , Igor Mammedov , Dan Williams , Eduardo Habkost 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 a file supporting DAX is used as vNVDIMM backend, mmap it with MAP_SYNC flag in addition can guarantee the persistence of guest write to the backend file without other QEMU actions (e.g., periodic fsync() by QEMU). A OnOffAuto parameter 'sync' is added to qemu_ram_mmap(): - If sync =3D=3D ON_OFF_AUTO_ON, qemu_ram_mmap() will try to pass MAP_SYNC to mmap(). It will then fail if the host OS or the backend file do not support MAP_SYNC, or MAP_SYNC is conflict with other flags. - If sync =3D=3D ON_OFF_AUTO_OFF, qemu_ram_mmap() will never pass MAP_SYNC to mmap(). - If sync =3D=3D ON_OFF_AUTO_AUTO, and * if the host OS and the backend file support MAP_SYNC, and MAP_SYNC is not conflict with other flags, qemu_ram_mmap() will work as if sync =3D=3D ON_OFF_AUTO_ON. * otherwise, qemu_ram_mmap() will work as if sync =3D=3D ON_OFF_AUTO_OFF. Signed-off-by: Haozhong Zhang --- exec.c | 2 +- include/qemu/mmap-alloc.h | 3 ++- include/qemu/osdep.h | 18 ++++++++++++++++++ util/mmap-alloc.c | 24 ++++++++++++++++++++++-- util/oslib-posix.c | 2 +- 5 files changed, 44 insertions(+), 5 deletions(-) diff --git a/exec.c b/exec.c index 8fba88ae1c..f4254cb6d3 100644 --- a/exec.c +++ b/exec.c @@ -1646,7 +1646,7 @@ static void *file_ram_alloc(RAMBlock *block, } =20 area =3D qemu_ram_mmap(fd, memory, block->mr->align, - block->flags & RAM_SHARED); + block->flags & RAM_SHARED, ON_OFF_AUTO_OFF); if (area =3D=3D MAP_FAILED) { error_setg_errno(errp, errno, "unable to map backing store for guest RAM"); diff --git a/include/qemu/mmap-alloc.h b/include/qemu/mmap-alloc.h index 50385e3f81..dd5876471f 100644 --- a/include/qemu/mmap-alloc.h +++ b/include/qemu/mmap-alloc.h @@ -7,7 +7,8 @@ size_t qemu_fd_getpagesize(int fd); =20 size_t qemu_mempath_getpagesize(const char *mem_path); =20 -void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared); +void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared, + OnOffAuto sync); =20 void qemu_ram_munmap(void *ptr, size_t size); =20 diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index adb3758275..0ff10cb529 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -372,6 +372,24 @@ void qemu_anon_ram_free(void *ptr, size_t size); # define QEMU_VMALLOC_ALIGN getpagesize() #endif =20 +/* + * MAP_SHARED_VALIDATE and MAP_SYNC were introduced in Linux kernel + * 4.15, so they may not be defined when compiling on older kernels. + */ +#ifdef CONFIG_LINUX +#ifndef MAP_SHARED_VALIDATE +#define MAP_SHARED_VALIDATE 0x3 +#endif +#ifndef MAP_SYNC +#define MAP_SYNC 0x80000 +#endif +#define QEMU_HAS_MAP_SYNC true +#else /* !CONFIG_LINUX */ +#define MAP_SHARED_VALIDATE 0x0 +#define MAP_SYNC 0x0 +#define QEMU_HAS_MAP_SYNC false +#endif /* CONFIG_LINUX */ + #ifdef CONFIG_POSIX struct qemu_signalfd_siginfo { uint32_t ssi_signo; /* Signal number */ diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 2fd8cbcc6f..b42d9719f3 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -73,7 +73,8 @@ size_t qemu_mempath_getpagesize(const char *mem_path) return getpagesize(); } =20 -void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared) +void *qemu_ram_mmap(int fd, size_t size, size_t align, bool shared, + OnOffAuto sync) { /* * Note: this always allocates at least one extra page of virtual addr= ess @@ -97,6 +98,7 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align, bo= ol shared) #endif size_t offset; void *ptr1; + int xflags =3D 0; =20 if (ptr =3D=3D MAP_FAILED) { return MAP_FAILED; @@ -106,13 +108,31 @@ void *qemu_ram_mmap(int fd, size_t size, size_t align= , bool shared) /* Always align to host page size */ assert(align >=3D getpagesize()); =20 + if (!QEMU_HAS_MAP_SYNC || !shared) { + if (sync =3D=3D ON_OFF_AUTO_ON) { + return MAP_FAILED; + } + sync =3D ON_OFF_AUTO_OFF; + } + if (sync !=3D ON_OFF_AUTO_OFF) { + /* MAP_SYNC is only available with MAP_SHARED_VALIDATE. */ + xflags |=3D MAP_SYNC | MAP_SHARED_VALIDATE; + } + offset =3D QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr; + retry_mmap_fd: ptr1 =3D mmap(ptr + offset, size, PROT_READ | PROT_WRITE, MAP_FIXED | (fd =3D=3D -1 ? MAP_ANONYMOUS : 0) | - (shared ? MAP_SHARED : MAP_PRIVATE), + (shared ? MAP_SHARED : MAP_PRIVATE) | xflags, fd, 0); if (ptr1 =3D=3D MAP_FAILED) { + if (sync =3D=3D ON_OFF_AUTO_AUTO) { + xflags &=3D ~(MAP_SYNC | MAP_SHARED_VALIDATE); + sync =3D ON_OFF_AUTO_OFF; + goto retry_mmap_fd; + } + munmap(ptr, total); return MAP_FAILED; } diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 77369c92ce..ecb1c275d2 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -130,7 +130,7 @@ void *qemu_memalign(size_t alignment, size_t size) void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment) { size_t align =3D QEMU_VMALLOC_ALIGN; - void *ptr =3D qemu_ram_mmap(-1, size, align, false); + void *ptr =3D qemu_ram_mmap(-1, size, align, false, ON_OFF_AUTO_OFF); =20 if (ptr =3D=3D MAP_FAILED) { return NULL; --=20 2.14.1