Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751160AbdCQN1G (ORCPT ); Fri, 17 Mar 2017 09:27:06 -0400 Received: from mail-it0-f42.google.com ([209.85.214.42]:36891 "EHLO mail-it0-f42.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751082AbdCQN1C (ORCPT ); Fri, 17 Mar 2017 09:27:02 -0400 MIME-Version: 1.0 In-Reply-To: <20170317020951.GA3942@dhcp-128-65.nay.redhat.com> References: <20170308201616.GC8598@vader> <20170309063806.GB17257@dhcp-128-65.nay.redhat.com> <20170309095408.GA17883@vader> <20170313073748.GA6332@dhcp-128-65.nay.redhat.com> <20170316124132.GF6261@codeblueprint.co.uk> <20170317020951.GA3942@dhcp-128-65.nay.redhat.com> From: Ard Biesheuvel Date: Fri, 17 Mar 2017 13:25:33 +0000 Message-ID: Subject: Re: kexec regression since 4.9 caused by efi To: Dave Young Cc: Matt Fleming , Omar Sandoval , Ingo Molnar , "linux-kernel@vger.kernel.org" , kernel-team@fb.com, "kexec@lists.infradead.org" , "linux-efi@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2619 Lines: 63 On 17 March 2017 at 02:09, Dave Young wrote: > On 03/16/17 at 12:41pm, Matt Fleming wrote: >> On Mon, 13 Mar, at 03:37:48PM, Dave Young wrote: >> > >> > Omar, could you try below patch? Looking at the efi_mem_desc_lookup, it is not >> > correct to be used in efi_arch_mem_reserve, if it passed your test, I >> > can rewrite patch log with more background and send it out: >> > >> > for_each_efi_memory_desc(md) { >> > [snip] >> > if (!(md->attribute & EFI_MEMORY_RUNTIME) && >> > md->type != EFI_BOOT_SERVICES_DATA && >> > md->type != EFI_RUNTIME_SERVICES_DATA) { >> > continue; >> > } >> > >> > In above code, it meant to get a md of EFI_MEMORY_RUNTIME of either boot >> > data or runtime data, this is wrong for efi_mem_reserve, because we are >> > reserving boot data which has no EFI_MEMORY_RUNTIME attribute at the >> > running time. Just is happened to work and we did not capture the error. >> >> Wouldn't something like this be simpler? >> >> --- >> >> diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c >> index 30031d5293c4..cdfe8c628959 100644 >> --- a/arch/x86/platform/efi/quirks.c >> +++ b/arch/x86/platform/efi/quirks.c >> @@ -201,6 +201,10 @@ void __init efi_arch_mem_reserve(phys_addr_t addr, u64 size) >> return; >> } >> >> + /* No need to reserve regions that will never be freed. */ >> + if (md.attribute & EFI_MEMORY_RUNTIME) >> + return; >> + > > Matt, I think it should be fine although I think the md type checking in > efi_mem_desc_lookup() is causing confusion and not easy to understand.. > > How about move the if chunk early like below because it seems no need > to sanity check the addr + size any more if the md is still RUNTIME? > > --- linux-x86.orig/arch/x86/platform/efi/quirks.c > +++ linux-x86/arch/x86/platform/efi/quirks.c > @@ -196,6 +196,10 @@ void __init efi_arch_mem_reserve(phys_ad > return; > } > > + /* No need to reserve regions that will never be freed. */ > + if (md.attribute & EFI_MEMORY_RUNTIME) > + return; > + > if (addr + size > md.phys_addr + (md.num_pages << EFI_PAGE_SHIFT)) { > pr_err("Region spans EFI memory descriptors, %pa\n", &addr); > return; > This way, we suppress the error it the region spans multiple descriptors, and only the first one has the runtime attribute. So the two patches are not equivalent. I don't have a strong preference either way, though.