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Tsirkin" To: Marc-Andre Lureau Cc: =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Linux Kernel Mailing List , Baoquan He , Sergio Lopez Pascual , "Somlo, Gabriel" , xiaolong.ye@intel.com Subject: Re: [PATCH v14 9/9] RFC: fw_cfg: do DMA read operation Message-ID: <20180214185818-mutt-send-email-mst@kernel.org> References: <20180214141850.4017-1-marcandre.lureau@redhat.com> <20180214141850.4017-10-marcandre.lureau@redhat.com> <20180214182714-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 14 Feb 2018 17:00:00 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.2]); Wed, 14 Feb 2018 17:00:00 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'mst@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 14, 2018 at 05:52:10PM +0100, Marc-Andre Lureau wrote: > >> @@ -282,8 +320,9 @@ static int fw_cfg_do_platform_probe(struct platform_device *pdev) > >> #endif > >> > >> /* verify fw_cfg device signature */ > >> - fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, 0, FW_CFG_SIG_SIZE); > >> - if (memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) { > >> + if (fw_cfg_read_blob(FW_CFG_SIGNATURE, sig, > >> + 0, FW_CFG_SIG_SIZE, false) < 0 || > >> + memcmp(sig, "QEMU", FW_CFG_SIG_SIZE) != 0) { > >> fw_cfg_io_cleanup(); > >> return -ENODEV; > >> } > > > > Rather than add dead code, how about a promise not to > > fail if dma is disabled? Patch will be smaller then. > > Even with dma disabled, you could have a locking bug which was > silently ignored before and is now taken into account. I see. I'd start with a patch reporting errors to users then. That would be a bugfix and can be merged for this version. > > > >> @@ -466,8 +505,8 @@ static ssize_t fw_cfg_sysfs_read_raw(struct file *filp, struct kobject *kobj, > >> if (count > entry->size - pos) > >> count = entry->size - pos; > >> > >> - fw_cfg_read_blob(entry->select, buf, pos, count); > >> - return count; > >> + /* do not use DMA, virt_to_phys(buf) might not be ok */ > >> + return fw_cfg_read_blob(entry->select, buf, pos, count, false); > >> } > >> > >> static struct bin_attribute fw_cfg_sysfs_attr_raw = { > >> @@ -632,7 +671,12 @@ static int fw_cfg_register_dir_entries(void) > >> struct fw_cfg_file *dir; > >> size_t dir_size; > >> > >> - fw_cfg_read_blob(FW_CFG_FILE_DIR, &files.count, 0, sizeof(files.count)); > >> + ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, &files.count, > >> + 0, sizeof(files.count), false); > >> + if (ret < 0) { > >> + return ret; > >> + } > >> + > >> count = be32_to_cpu(files.count); > >> dir_size = count * sizeof(struct fw_cfg_file); > >> > >> @@ -640,7 +684,11 @@ static int fw_cfg_register_dir_entries(void) > >> if (!dir) > >> return -ENOMEM; > >> > >> - fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, sizeof(files.count), dir_size); > >> + ret = fw_cfg_read_blob(FW_CFG_FILE_DIR, dir, > >> + sizeof(files.count), dir_size, false); > >> + if (ret < 0) { > >> + goto end; > >> + } > >> > >> for (i = 0; i < count; i++) { > >> ret = fw_cfg_register_file(&dir[i]); > >> @@ -648,6 +696,7 @@ static int fw_cfg_register_dir_entries(void) > >> break; > >> } > >> > >> +end: > >> kfree(dir); > >> return ret; > >> } > >> @@ -688,7 +737,10 @@ static int fw_cfg_sysfs_probe(struct platform_device *pdev) > >> goto err_probe; > >> > >> /* get revision number, add matching top-level attribute */ > >> - fw_cfg_read_blob(FW_CFG_ID, &rev, 0, sizeof(rev)); > >> + err = fw_cfg_read_blob(FW_CFG_ID, &rev, 0, sizeof(rev), false); > >> + if (err < 0) { > >> + goto err_probe; > >> + } > >> fw_cfg_rev = le32_to_cpu(rev); > >> err = sysfs_create_file(fw_cfg_top_ko, &fw_cfg_rev_attr.attr); > >> if (err) > >> -- > >> 2.16.1.73.g5832b7e9f2