From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH v2] firmware: qemu_fw_cfg.c: hold ACPI global lock during device access Date: Thu, 17 Mar 2016 14:13:54 +0100 Message-ID: <56EAAD92.10007@redhat.com> References: <20160308183050.GJ2049@HEDWIG.INI.CMU.EDU> <20160316185440-mutt-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20160316185440-mutt-send-email-mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Michael S. Tsirkin" , Gabriel Somlo Cc: Greg KH , robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org, galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, lersek-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, ralf-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org, rmk+kernel-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org, eric-WhKQ6XTQaPysTnJN9+BGXg@public.gmane.org, hanjun.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, zajec5-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, sudeep.holla-5wv7dgnIgG8@public.gmane.org, agross-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org, imammedo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, peter.maydell-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, kraxel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, ehabkost-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org, stefanha-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, revol-GANU6spQydw@public.gmane.org, matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org, rth-hL46jP5Bxq7R7s880joybQ@public.gmane.org List-Id: linux-api@vger.kernel.org On 16/03/2016 17:57, Michael S. Tsirkin wrote: > On Tue, Mar 08, 2016 at 01:30:50PM -0500, Gabriel Somlo wrote: >> Allowing for the future possibility of implementing AML-based >> (i.e., firmware-triggered) access to the QEMU fw_cfg device, >> acquire the global ACPI lock when accessing the device on behalf >> of the guest-side sysfs driver, to prevent any potential race >> conditions. >> >> Suggested-by: Michael S. Tsirkin >> Signed-off-by: Gabriel Somlo > > So this patch makes sense of course. > > > Given the recent discussion on QEMU mailing list, > I think there is an additional patch that we need: > filter the files exposed to userspace by "opt/" prefix. > > This will ensure that we can change all other fw cfg files > at will without breaking guest scripts. That makes no sense, all other fw_cfg files are firmware ABI so we cannot change them anyway. Paolo