From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Fleming Subject: Re: [PATCH 4/4] x86, efi: Map runtime services 1:1 Date: Thu, 6 Jun 2013 14:14:39 +0100 Message-ID: <20130606131439.GI30420@console-pimps.org> References: <1370177770-26661-1-git-send-email-bp@alien8.de> <1370177770-26661-5-git-send-email-bp@alien8.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1370177770-26661-5-git-send-email-bp-Gina5bIWoIWzQB+pC5nmwQ@public.gmane.org> Sender: linux-efi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Borislav Petkov Cc: Linux EFI , Matthew Garrett , Jiri Kosina , X86-ML , LKML , Borislav Petkov List-Id: linux-efi@vger.kernel.org On Sun, 02 Jun, at 02:56:10PM, Borislav Petkov wrote: > From: Borislav Petkov > > Due to the braindead design of EFI, we cannot map runtime services more > than once for the duration of a booted system. Thus, if we want to use > EFI runtime services in a kexec'ed kernel, maybe the only possible and > sensible approach would be to map them 1:1 so that when the kexec kernel > loads, it can simply call those addresses without the need for remapping > (which doesn't work anyway). > > Furthermore, this mapping approach could be of help with b0rked EFI > implementations for a different set of reasons. > > This implementation is 64-bit only for now and it boots fine in kvm with > OVMF BIOS. > > Signed-off-by: Borislav Petkov > --- > arch/x86/include/asm/efi.h | 2 + > arch/x86/platform/efi/efi.c | 161 +++++++++++++++++++++++++++++------- > arch/x86/platform/efi/efi_stub_64.S | 48 +++++++++++ > 3 files changed, 180 insertions(+), 31 deletions(-) This patch makes my TunnelMountain machine spin in handle_pte_fault() when triggering one of the "firmware makes references to physical addresses" code paths. I'll try and dig into this tomorrow to figure out what's going on. -- Matt Fleming, Intel Open Source Technology Center