From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34077) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YieuK-0006oR-Ax for qemu-devel@nongnu.org; Thu, 16 Apr 2015 04:12:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YieuG-0000zZ-S5 for qemu-devel@nongnu.org; Thu, 16 Apr 2015 04:12:20 -0400 Received: from mail-wi0-x229.google.com ([2a00:1450:400c:c05::229]:33317) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YieuG-0000zQ-Ld for qemu-devel@nongnu.org; Thu, 16 Apr 2015 04:12:16 -0400 Received: by wiax7 with SMTP id x7so5749861wia.0 for ; Thu, 16 Apr 2015 01:12:16 -0700 (PDT) Sender: Paolo Bonzini Message-ID: <552F6EDC.4040900@redhat.com> Date: Thu, 16 Apr 2015 10:12:12 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1429017160-3583-1-git-send-email-kraxel@redhat.com> <552D259E.405@redhat.com> <1429106337.6219.5.camel@nilsson.home.kraxel.org> In-Reply-To: <1429106337.6219.5.camel@nilsson.home.kraxel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Subject: Re: [Qemu-devel] [PATCH 1/2] q35: implement SMRAM.D_LCK List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gerd Hoffmann Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" On 15/04/2015 15:58, Gerd Hoffmann wrote: > The "A Tour Beyond BIOS Implementing S3 Resume with EDKII" white paper > lists "Lock SMM. This must be done to maintain SMM integrity." as todo > list item for the edk2 resume code path (page 18). > > So it seems to me it is the job of the firmware to re-lock smm after S3 > (and before handing control back to the OS, obviously). Right, however "D_LCK can be set to 1 via a normal configuration space write but can only be cleared by a Full Reset." A Full Reset is the PLTRST# pin, which is asserted by the south bridge during power-up and during CF9h reset. S3 doesn't seem to be included. My reading of the EDK2 whitepaper is that this may vary for other chipsets. Paolo