From nobody Sat Nov 8 08:05:04 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=linux.intel.com Return-Path: Received: from lists.gnu.org (209.51.188.17 [209.51.188.17]) by mx.zohomail.com with SMTPS id 1549590275421696.6989062442769; Thu, 7 Feb 2019 17:44:35 -0800 (PST) Received: from localhost ([127.0.0.1]:49554 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1grvDR-0002my-9x for importer@patchew.org; Thu, 07 Feb 2019 20:44:29 -0500 Received: from eggs.gnu.org ([209.51.188.92]:60737) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1grvA2-0000mX-9J for qemu-devel@nongnu.org; Thu, 07 Feb 2019 20:40:59 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1grvA0-000563-Dg for qemu-devel@nongnu.org; Thu, 07 Feb 2019 20:40:58 -0500 Received: from mga12.intel.com ([192.55.52.136]:39253) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1grv9z-0004xR-Dm for qemu-devel@nongnu.org; Thu, 07 Feb 2019 20:40:56 -0500 Received: from orsmga007.jf.intel.com ([10.7.209.58]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 07 Feb 2019 17:40:26 -0800 Received: from dazhang1-ssd.sh.intel.com (HELO localhost) ([10.239.48.91]) by orsmga007.jf.intel.com with ESMTP; 07 Feb 2019 17:40:24 -0800 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.58,346,1544515200"; d="scan'208";a="113283279" From: "Zhang, Yi" To: xiaoguangrong.eric@gmail.com, stefanha@redhat.com, pbonzini@redhat.com, pagupta@redhat.com, yu.c.zhang@linux.intel.com, richardw.yang@linux.intel.com, mst@redhat.com, ehabkost@redhat.com Date: Fri, 8 Feb 2019 18:11:11 +0800 Message-Id: <5d07bf7e9a3e576f5a87e81d786e8886fb2bb551.1549555521.git.yi.z.zhang@linux.intel.com> 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 V13 4/5] 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: imammedo@redhat.com, dan.j.williams@intel.com, qemu-devel@nongnu.org, Zhang Yi Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" From: Zhang Yi When a file supporting DAX is used as vNVDIMM backend, mmap it with MAP_SYNC flag in addition which can ensure file system metadata synced in each guest writes to the backend file, without other QEMU actions (e.g., periodic fsync() by QEMU). Current, We have below different possible use cases: 1. pmem=3Don is set, shared=3Don is set, MAP_SYNC supported: a: backend is a dax supporting file. - MAP_SYNC will active. b: backend is not a dax supporting file. - mmap will trigger a warning. then MAP_SYNC flag will be ignored 2. The rest of cases: - we will never pass the MAP_SYNC to mmap2 Signed-off-by: Haozhong Zhang Signed-off-by: Zhang Yi --- util/mmap-alloc.c | 45 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 44 insertions(+), 1 deletion(-) diff --git a/util/mmap-alloc.c b/util/mmap-alloc.c index 97bbeed..2f21efd 100644 --- a/util/mmap-alloc.c +++ b/util/mmap-alloc.c @@ -10,6 +10,13 @@ * later. See the COPYING file in the top-level directory. */ =20 +#ifdef CONFIG_LINUX +#include +#else /* !CONFIG_LINUX */ +#define MAP_SYNC 0x0 +#define MAP_SHARED_VALIDATE 0x0 +#endif /* CONFIG_LINUX */ + #include "qemu/osdep.h" #include "qemu/mmap-alloc.h" #include "qemu/host-utils.h" @@ -101,6 +108,8 @@ void *qemu_ram_mmap(int fd, #else void *ptr =3D mmap(0, total, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE, -= 1, 0); #endif + int mmap_flags; + int map_sync_flags =3D 0; size_t offset; void *ptr1; =20 @@ -111,13 +120,47 @@ void *qemu_ram_mmap(int fd, assert(is_power_of_2(align)); /* Always align to host page size */ assert(align >=3D getpagesize()); + mmap_flags =3D shared ? MAP_SHARED : MAP_PRIVATE; + if (shared && is_pmem) { + map_sync_flags =3D MAP_SYNC | MAP_SHARED_VALIDATE; + mmap_flags |=3D map_sync_flags; + } =20 offset =3D QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr; ptr1 =3D mmap(ptr + offset, size, PROT_READ | PROT_WRITE, MAP_FIXED | (fd =3D=3D -1 ? MAP_ANONYMOUS : 0) | - (shared ? MAP_SHARED : MAP_PRIVATE), + mmap_flags, fd, 0); + + + if (ptr1 =3D=3D MAP_FAILED && map_sync_flags) { + if (errno =3D=3D ENOTSUP) { + char *proc_link, *file_name; + int len; + proc_link =3D g_strdup_printf("/proc/self/fd/%d", fd); + file_name =3D g_malloc0(PATH_MAX); + len =3D readlink(proc_link, file_name, PATH_MAX - 1); + if (len < 0) { + len =3D 0; + } + file_name[len] =3D '\0'; + fprintf(stderr, "Warning: requesting persistence across crashe= s " + "for backend file %s failed. Proceeding without " + "persistence, data might become corrupted in case of h= ost " + "crash.\n", file_name); + g_free(proc_link); + g_free(file_name); + } + /* if map failed with MAP_SHARED_VALIDATE | MAP_SYNC, + * we will remove these flags to handle compatibility. + */ + ptr1 =3D mmap(ptr + offset, size, PROT_READ | PROT_WRITE, + MAP_FIXED | + (fd =3D=3D -1 ? MAP_ANONYMOUS : 0) | + MAP_SHARED, + fd, 0); + } if (ptr1 =3D=3D MAP_FAILED) { munmap(ptr, total); return MAP_FAILED; --=20 2.7.4