From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753123AbeDFNXd (ORCPT ); Fri, 6 Apr 2018 09:23:33 -0400 Received: from mx2.suse.de ([195.135.220.15]:58182 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752848AbeDFNXc (ORCPT ); Fri, 6 Apr 2018 09:23:32 -0400 Date: Fri, 06 Apr 2018 15:23:30 +0200 Message-ID: From: Takashi Iwai To: Stuart Hayes Cc: linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: [PATCH v4] dell_rbu: make firmware payload memory uncachable In-Reply-To: References: User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 06 Apr 2018 15:12:21 +0200, Stuart Hayes wrote: > > The dell_rbu driver takes firmware update payloads and puts them in memory so > the system BIOS can find them after a reboot. This sometimes fails (though > rarely), because the memory containing the payload is in the CPU cache but > never gets written back to main memory before the system is rebooted (CPU > cache contents are lost on reboot). > > With this patch, the payload memory will be changed to uncachable to ensure > that the payload is actually in main memory before the system is rebooted. > > Signed-off-by: Stuart Hayes Looks good to me. Reviewed-by: Takashi Iwai Andrew, could you pick this one? The driver seems to have no maintainer. thanks, Takashi > --- > v2 Added include, removed extra parentheses > v3 Corrected formatting and include line > v4 Moved set_memory_uc() outside the while loop so that the memory is > definitely allocated before it is set to uncachable > > This driver has no maintainer. > > > diff --git a/drivers/firmware/dell_rbu.c b/drivers/firmware/dell_rbu.c > index 2f452f1f7c8a..53f27a6e2d76 100644 > --- a/drivers/firmware/dell_rbu.c > +++ b/drivers/firmware/dell_rbu.c > @@ -45,6 +45,7 @@ > #include > #include > #include > +#include > > MODULE_AUTHOR("Abhay Salunke "); > MODULE_DESCRIPTION("Driver for updating BIOS image on DELL systems"); > @@ -181,6 +182,11 @@ static int create_packet(void *data, size_t length) > packet_data_temp_buf = NULL; > } > } > + /* > + * set to uncachable or it may never get written back before reboot > + */ > + set_memory_uc((unsigned long)packet_data_temp_buf, 1 << ordernum); > + > spin_lock(&rbu_data.lock); > > newpacket->data = packet_data_temp_buf; > @@ -349,6 +355,8 @@ static void packet_empty_list(void) > * to make sure there are no stale RBU packets left in memory > */ > memset(newpacket->data, 0, rbu_data.packetsize); > + set_memory_wb((unsigned long)newpacket->data, > + 1 << newpacket->ordernum); > free_pages((unsigned long) newpacket->data, > newpacket->ordernum); > kfree(newpacket); >