From patchwork Wed Feb 13 07:14:01 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 1041011 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=209.51.188.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 43zrjM0Ln9z9s7T for ; Wed, 13 Feb 2019 18:28:22 +1100 (AEDT) Received: from localhost ([127.0.0.1]:52303 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gtoxv-0007AQ-G4 for incoming@patchwork.ozlabs.org; Wed, 13 Feb 2019 02:28:19 -0500 Received: from eggs.gnu.org ([209.51.188.92]:37346) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gtoxW-00070L-UB for qemu-devel@nongnu.org; Wed, 13 Feb 2019 02:27:56 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gtokD-00055T-1b for qemu-devel@nongnu.org; Wed, 13 Feb 2019 02:14:10 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58598) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gtokC-000552-PO for qemu-devel@nongnu.org; Wed, 13 Feb 2019 02:14:08 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AA2A066983; Wed, 13 Feb 2019 07:14:07 +0000 (UTC) Received: from localhost (unknown [10.64.242.79]) by smtp.corp.redhat.com (Postfix) with ESMTP id 87C775C1B2; Wed, 13 Feb 2019 07:14:03 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Wed, 13 Feb 2019 15:14:01 +0800 Message-Id: <20190213071401.11544-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Wed, 13 Feb 2019 07:14:08 +0000 (UTC) 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 v2] hostmem-file: reject invalid pmem file sizes 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 , Stefan Weil , Zhang Yi , Stefan Hajnoczi , Igor Mammedov Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" Guests started with NVDIMMs larger than the underlying host file produce confusing errors inside the guest. This happens because the guest accesses pages beyond the end of the file. Check the pmem file size on startup and print a clear error message if the size is invalid. Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1669053 Cc: Haozhong Zhang Cc: Zhang Yi Cc: Eduardo Habkost Cc: Igor Mammedov Signed-off-by: Stefan Hajnoczi --- v2: * Propagate qemu_get_pmem_size() errors [Igor] include/qemu/osdep.h | 13 ++++++++++ backends/hostmem-file.c | 22 +++++++++++++++++ util/oslib-posix.c | 53 +++++++++++++++++++++++++++++++++++++++++ util/oslib-win32.c | 5 ++++ 4 files changed, 93 insertions(+) diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h index 840af09cb0..303d315c5d 100644 --- a/include/qemu/osdep.h +++ b/include/qemu/osdep.h @@ -570,6 +570,19 @@ 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); +/** + * 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 files 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 ba601ce940..d62689179b 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -46,6 +46,28 @@ file_backend_memory_alloc(HostMemoryBackend *backend, Error **errp) gchar *name; #endif + /* + * Verify pmem file size since starting a guest with an incorrect size + * leads to confusing failures inside the guest. + */ + if (fb->is_pmem && fb->mem_path) { + Error *local_err = NULL; + uint64_t size; + + size = 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; + } + } + if (!backend->size) { error_setg(errp, "can't create backend with size 0"); return; diff --git a/util/oslib-posix.c b/util/oslib-posix.c index 37c5854b9c..10d90d1783 100644 --- a/util/oslib-posix.c +++ b/util/oslib-posix.c @@ -500,6 +500,59 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus, } } +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 = NULL; + char *subsystem = NULL; + char *size_path = NULL; + char *size_str = NULL; + uint64_t ret = 0; + + subsystem_path = g_strdup_printf("/sys/dev/char/%d:%d/subsystem", + major(st.st_rdev), minor(st.st_rdev)); + subsystem = 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", filename); + goto devdax_err; + } + + size_path = 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 = 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) { diff --git a/util/oslib-win32.c b/util/oslib-win32.c index b4c17f5dfa..bd633afab6 100644 --- a/util/oslib-win32.c +++ b/util/oslib-win32.c @@ -560,6 +560,11 @@ void os_mem_prealloc(int fd, char *area, size_t memory, int smp_cpus, } } +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) {