From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17391C3A5A4 for ; Fri, 30 Aug 2019 09:32:51 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E369921726 for ; Fri, 30 Aug 2019 09:32:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E369921726 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:57508 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3dH0-0005hx-46 for qemu-devel@archiver.kernel.org; Fri, 30 Aug 2019 05:32:50 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:42955) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1i3dFT-0005Fm-Sv for qemu-devel@nongnu.org; Fri, 30 Aug 2019 05:31:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1i3dFN-0003LB-0c for qemu-devel@nongnu.org; Fri, 30 Aug 2019 05:31:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44394) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1i3dFJ-0003BQ-2s for qemu-devel@nongnu.org; Fri, 30 Aug 2019 05:31:06 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 649DC10C6979; Fri, 30 Aug 2019 09:31:00 +0000 (UTC) Received: from localhost (unknown [10.36.118.88]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8847160F86; Fri, 30 Aug 2019 09:30:57 +0000 (UTC) From: Stefan Hajnoczi To: Date: Fri, 30 Aug 2019 10:30:56 +0100 Message-Id: <20190830093056.12572-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.65]); Fri, 30 Aug 2019 09:31:00 +0000 (UTC) Content-Transfer-Encoding: quoted-printable X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH] memory: fetch pmem size in get_file_size() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Haozhong Zhang , Eduardo Habkost , Stefan Weil , Junyan He , Stefan Hajnoczi , Igor Mammedov , Paolo Bonzini , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Neither stat(2) nor lseek(2) report the size of Linux devdax pmem character device nodes. Commit 314aec4a6e06844937f1677f6cba21981005f389 ("hostmem-file: reject invalid pmem file sizes") added code to hostmem-file.c to fetch the size from sysfs and compare against the user-provided size=3DNUM parameter: if (backend->size > size) { error_setg(errp, "size property %" PRIu64 " is larger than " "pmem file \"%s\" size %" PRIu64, backend->size, fb->mem_path, size); return; } It turns out that exec.c:qemu_ram_alloc_from_fd() already has an equivalent size check but it skips devdax pmem character devices because lseek(2) returns 0: if (file_size > 0 && file_size < size) { error_setg(errp, "backing store %s size 0x%" PRIx64 " does not match 'size' option 0x" RAM_ADDR_FMT, mem_path, file_size, size); return NULL; } This patch moves the devdax pmem file size code into get_file_size() so that we check the memory size in a single place: qemu_ram_alloc_from_fd(). This simplifies the code and makes it more general. This also fixes the problem that hostmem-file only checks the devdax pmem file size when the pmem=3Don parameter is given. An unchecked size=3DNUM parameter can lead to SIGBUS in QEMU so we must always fetch the file size for Linux devdax pmem character device nodes. Signed-off-by: Stefan Hajnoczi --- Note that this patch conflicts with "[PATCH] hostmem-file: fix pmem file size check" but it obsoletes that patch, so the conflict can be resolved simply by taking this patch instead of the older one. include/qemu/osdep.h | 13 ---------- backends/hostmem-file.c | 22 ----------------- exec.c | 34 +++++++++++++++++++++++++- util/oslib-posix.c | 54 ----------------------------------------- util/oslib-win32.c | 6 ----- 5 files changed, 33 insertions(+), 96 deletions(-) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index af2b91f0b8..c7d242f476 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -570,19 +570,6 @@ void qemu_set_tty_echo(int fd, bool echo); void os_mem_prealloc(int fd, char *area, size_t sz, int smp_cpus, Error **errp); =20 -/** - * qemu_get_pmem_size: - * @filename: path to a pmem file - * @errp: pointer to a NULL-initialized error object - * - * Determine the size of a persistent memory file. Besides supporting f= iles on - * DAX file systems, this function also supports Linux devdax character - * devices. - * - * Returns: the size or 0 on failure - */ -uint64_t qemu_get_pmem_size(const char *filename, Error **errp); - /** * qemu_get_pid_name: * @pid: pid of a process diff --git a/backends/hostmem-file.c b/backends/hostmem-file.c index 29e55c9195..be64020746 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -58,28 +58,6 @@ file_backend_memory_alloc(HostMemoryBackend *backend, = Error **errp) return; } =20 - /* - * Verify pmem file size since starting a guest with an incorrect si= ze - * leads to confusing failures inside the guest. - */ - if (fb->is_pmem) { - Error *local_err =3D NULL; - uint64_t size; - - size =3D qemu_get_pmem_size(fb->mem_path, &local_err); - if (!size) { - error_propagate(errp, local_err); - return; - } - - if (backend->size > size) { - error_setg(errp, "size property %" PRIu64 " is larger than " - "pmem file \"%s\" size %" PRIu64, backend->size, - fb->mem_path, size); - return; - } - } - backend->force_prealloc =3D mem_prealloc; name =3D host_memory_backend_get_name(backend); memory_region_init_ram_from_file(&backend->mr, OBJECT(backend), diff --git a/exec.c b/exec.c index 1df966d17a..80150420a8 100644 --- a/exec.c +++ b/exec.c @@ -1814,7 +1814,39 @@ long qemu_maxrampagesize(void) #ifdef CONFIG_POSIX static int64_t get_file_size(int fd) { - int64_t size =3D lseek(fd, 0, SEEK_END); + int64_t size; +#if defined(__linux__) + struct stat st; + + if (fstat(fd, &st) < 0) { + return -errno; + } + + /* Special handling for devdax character devices */ + if (S_ISCHR(st.st_mode)) { + g_autofree char *subsystem_path =3D NULL; + g_autofree char *subsystem =3D NULL; + + subsystem_path =3D g_strdup_printf("/sys/dev/char/%d:%d/subsyste= m", + major(st.st_rdev), minor(st.st_= rdev)); + subsystem =3D g_file_read_link(subsystem_path, NULL); + + if (subsystem && g_str_has_suffix(subsystem, "/dax")) { + g_autofree char *size_path =3D NULL; + g_autofree char *size_str =3D NULL; + + size_path =3D g_strdup_printf("/sys/dev/char/%d:%d/size", + major(st.st_rdev), minor(st.st_rdev)= ); + + if (g_file_get_contents(size_path, &size_str, NULL, NULL)) { + return g_ascii_strtoll(size_str, NULL, 0); + } + } + } +#endif /* defined(__linux__) */ + + /* st.st_size may be zero for special files yet lseek(2) works */ + size =3D lseek(fd, 0, SEEK_END); if (size < 0) { return -errno; } diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 5fda67dedf..f8693384fc 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -514,60 +514,6 @@ void os_mem_prealloc(int fd, char *area, size_t memo= ry, int smp_cpus, } } =20 -uint64_t qemu_get_pmem_size(const char *filename, Error **errp) -{ - struct stat st; - - if (stat(filename, &st) < 0) { - error_setg(errp, "unable to stat pmem file \"%s\"", filename); - return 0; - } - -#if defined(__linux__) - /* Special handling for devdax character devices */ - if (S_ISCHR(st.st_mode)) { - char *subsystem_path =3D NULL; - char *subsystem =3D NULL; - char *size_path =3D NULL; - char *size_str =3D NULL; - uint64_t ret =3D 0; - - subsystem_path =3D g_strdup_printf("/sys/dev/char/%d:%d/subsyste= m", - major(st.st_rdev), minor(st.st_= rdev)); - subsystem =3D g_file_read_link(subsystem_path, NULL); - if (!subsystem) { - error_setg(errp, "unable to read subsystem for pmem file \"%= s\"", - filename); - goto devdax_err; - } - - if (!g_str_has_suffix(subsystem, "/dax")) { - error_setg(errp, "pmem file \"%s\" is not a dax device", fil= ename); - goto devdax_err; - } - - size_path =3D g_strdup_printf("/sys/dev/char/%d:%d/size", - major(st.st_rdev), minor(st.st_rdev)= ); - if (!g_file_get_contents(size_path, &size_str, NULL, NULL)) { - error_setg(errp, "unable to read size for pmem file \"%s\"", - size_path); - goto devdax_err; - } - - ret =3D g_ascii_strtoull(size_str, NULL, 0); - -devdax_err: - g_free(size_str); - g_free(size_path); - g_free(subsystem); - g_free(subsystem_path); - return ret; - } -#endif /* defined(__linux__) */ - - return st.st_size; -} - char *qemu_get_pid_name(pid_t pid) { char *name =3D NULL; diff --git a/util/oslib-win32.c b/util/oslib-win32.c index 9583fb4ca4..c62cd4328c 100644 --- a/util/oslib-win32.c +++ b/util/oslib-win32.c @@ -562,12 +562,6 @@ void os_mem_prealloc(int fd, char *area, size_t memo= ry, int smp_cpus, } } =20 -uint64_t qemu_get_pmem_size(const char *filename, Error **errp) -{ - error_setg(errp, "pmem support not available"); - return 0; -} - char *qemu_get_pid_name(pid_t pid) { /* XXX Implement me */ --=20 2.21.0