From: joeyli Subject: Re: [PATCH 11/18] Hibernate: introduced RSA key-pair to verify signature of snapshot Date: Thu, 05 Sep 2013 21:28:57 +0800 Message-ID: <1378387737.6193.75.camel__11042.2406382442$1378387729$gmane$org@linux-s257.site> References: <1377169317-5959-1-git-send-email-jlee@suse.com> <1377169317-5959-12-git-send-email-jlee@suse.com> <20130905085348.GJ28598@console-pimps.org> <1378376016.6193.71.camel@linux-s257.site> <20130905103158.GM28598@console-pimps.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org, linux-pm@vger.kernel.org, linux-crypto@vger.kernel.org, opensuse-kernel@opensuse.org, David Howells , "Rafael J. Wysocki" , Matthew Garrett , Len Brown , Pavel Machek , Josh Boyer , Vojtech Pavlik , Matt Fleming , James Bottomley , Greg KH , JKosina@suse.com, Rusty Russell , Herbert Xu , "David S. Miller" , "H. Peter Anvin" , Michal Marek , Gary Lin , Vivek Goyal , Takashi Iwai To: Matt Fleming Return-path: In-Reply-To: <20130905103158.GM28598@console-pimps.org> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org =E6=96=BC =E5=9B=9B=EF=BC=8C2013-09-05 =E6=96=BC 11:31 +0100=EF=BC=8CMa= tt Fleming =E6=8F=90=E5=88=B0=EF=BC=9A > On Thu, 05 Sep, at 06:13:36PM, joeyli wrote: > > This S4WakeKey is a VOLATILE variable that could not modify by > > SetVariable() at runtime. So, it's read only even through efivars.=20 > >=20 > > Does it what your concern? > =20 > No, the UEFI spec probibits certain runtime functions from being > executed concurrently on separate cpus and the spinlock used in the > efivars code ensures that we adhere to that restriction. See table 31= in > section 7.1 of the UEFI 2.4 spec for the list of services that are > non-reentrant. >=20 > The problem isn't that we want to avoid simultaneous access to > S4WakeKey, it's that we can't invoke any of the variable runtime serv= ice > functions concurrently. >=20 I see! I will use efivar api to access EFI variable. Thanks a lot! Joey Lee