From patchwork Tue Feb 12 02:52:41 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Hajnoczi X-Patchwork-Id: 1040333 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 43z6fw3dY7z9s5c for ; Tue, 12 Feb 2019 13:53:39 +1100 (AEDT) Received: from localhost ([127.0.0.1]:60164 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gtOCS-00015l-7G for incoming@patchwork.ozlabs.org; Mon, 11 Feb 2019 21:53:32 -0500 Received: from eggs.gnu.org ([209.51.188.92]:37868) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gtOC1-00015T-4k for qemu-devel@nongnu.org; Mon, 11 Feb 2019 21:53:06 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gtOBz-0002Dz-TG for qemu-devel@nongnu.org; Mon, 11 Feb 2019 21:53:05 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42222) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gtOBz-0002CD-K9 for qemu-devel@nongnu.org; Mon, 11 Feb 2019 21:53:03 -0500 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1BF964902D; Tue, 12 Feb 2019 02:53:02 +0000 (UTC) Received: from localhost (unknown [10.64.242.24]) by smtp.corp.redhat.com (Postfix) with ESMTP id ED0EB10027DC; Tue, 12 Feb 2019 02:52:57 +0000 (UTC) From: Stefan Hajnoczi To: qemu-devel@nongnu.org Date: Tue, 12 Feb 2019 10:52:41 +0800 Message-Id: <20190212025241.5330-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Tue, 12 Feb 2019 02:53:02 +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] 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 Reviewed-by: Pankaj Gupta --- include/qemu/osdep.h | 13 ++++++++++ backends/hostmem-file.c | 16 +++++++++++++ util/oslib-posix.c | 53 +++++++++++++++++++++++++++++++++++++++++ util/oslib-win32.c | 5 ++++ 4 files changed, 87 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..325ab4aad9 100644 --- a/backends/hostmem-file.c +++ b/backends/hostmem-file.c @@ -46,6 +46,22 @@ 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) { + uint64_t size; + + size = qemu_get_pmem_size(fb->mem_path, NULL); + if (size && 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) {