From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Young Subject: Re: [PATCH v5 31/32] x86: Add sysfs support for Secure Memory Encryption Date: Fri, 26 May 2017 10:49:33 +0800 Message-ID: <20170526024933.GA3228@dhcp-128-65.nay.redhat.com> References: <20170418211612.10190.82788.stgit@tlendack-t1.amdoffice.net> <20170418212212.10190.73484.stgit@tlendack-t1.amdoffice.net> <20170518170153.eqiyat5s6q3yeejl@pd.tnic> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20170518170153.eqiyat5s6q3yeejl-fF5Pk5pvG8Y@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Borislav Petkov Cc: linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Brijesh Singh , Toshimitsu Kani , Radim =?utf-8?B?S3LEjW3DocWZ?= , Matt Fleming , x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Alexander Potapenko , "H. Peter Anvin" , Larry Woodman , linux-arch-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Jonathan Corbet , linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kasan-dev-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org, Ingo Molnar , Andrey Ryabinin , Tom Lendacky , Rik van Riel , Arnd Bergmann , Andy Lutomirski , Thomas Gleixner , Dmitry Vyukov , kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Michael S. Tsirkin List-Id: linux-efi@vger.kernel.org Ccing Xunlei he is reading the patches see what need to be done for kdump. There should still be several places to handle to make kdump work. On 05/18/17 at 07:01pm, Borislav Petkov wrote: > On Tue, Apr 18, 2017 at 04:22:12PM -0500, Tom Lendacky wrote: > > Add sysfs support for SME so that user-space utilities (kdump, etc.) can > > determine if SME is active. > > But why do user-space tools need to know that? > > I mean, when we load the kdump kernel, we do it with the first kernel, > with the kexec_load() syscall, AFAICT. And that code does a lot of > things during that init, like machine_kexec_prepare()->init_pgtable() to > prepare the ident mapping of the second kernel, for example. > > What I'm aiming at is that the first kernel knows *exactly* whether SME > is enabled or not and doesn't need to tell the second one through some > sysfs entries - it can do that during loading. > > So I don't think we need any userspace things at all... If kdump kernel can get the SME status from hardware register then this should be not necessary and this patch can be dropped. Thanks Dave