From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120] helo=us-smtp-1.mimecast.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1ilZVJ-0003qG-Lw for kexec@lists.infradead.org; Sun, 29 Dec 2019 14:25:16 +0000 Date: Sun, 29 Dec 2019 22:24:53 +0800 From: Dave Young Subject: Re: [PATCH] x86/efi: update e820 about reserved EFI boot services data to fix kexec breakage Message-ID: <20191229142453.GA18486@dhcp-128-65.nay.redhat.com> References: <20191204075233.GA10520@dhcp-128-65.nay.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Dan Williams Cc: Michael Weiser , linux-efi , Ard Biesheuvel , X86 ML , kexec@lists.infradead.org, Linux Kernel Mailing List , Ingo Molnar , Borislav Petkov , "Eric W. Biederman" , Dan Williams , "H. Peter Anvin" , Thomas Gleixner Hi Dan, On 12/28/19 at 10:13pm, Dan Williams wrote: > On Sat, Dec 28, 2019 at 12:54 PM Dan Williams > wrote: > > > > On Tue, Dec 3, 2019 at 11:53 PM Dave Young wrote: > > > > > > Michael Weiser reported he got below error during a kexec rebooting: > > > esrt: Unsupported ESRT version 2904149718861218184. > > > > > > The ESRT memory stays in EFI boot services data, and it was reserved > > > in kernel via efi_mem_reserve(). The initial purpose of the reservation > > > is to reuse the EFI boot services data across kexec reboot. For example > > > the BGRT image data and some ESRT memory like Michael reported. > > > > > > But although the memory is reserved it is not updated in X86 e820 table. > > > And kexec_file_load iterate system ram in io resource list to find places > > > for kernel, initramfs and other stuff. In Michael's case the kexec loaded > > > initramfs overwritten the ESRT memory and then the failure happened. > > > > > > Since kexec_file_load depends on the e820 to be updated, just fix this > > > by updating the reserved EFI boot services memory as reserved type in e820. > > > > > > Originally any memory descriptors with EFI_MEMORY_RUNTIME attribute are > > > bypassed in the reservation code path because they are assumed as reserved. > > > But the reservation is still needed for multiple kexec reboot. > > > And it is the only possible case we come here thus just drop the code > > > chunk then everything works without side effects. > > > > > > On my machine the ESRT memory sits in an EFI runtime data range, it does > > > not trigger the problem, but I successfully tested with BGRT instead. > > > both kexec_load and kexec_file_load work and kdump works as well. > > > > > > Signed-off-by: Dave Young > > > --- > > > arch/x86/platform/efi/quirks.c | 6 ++---- > > > 1 file changed, 2 insertions(+), 4 deletions(-) > > > > > > --- linux-x86.orig/arch/x86/platform/efi/quirks.c > > > +++ linux-x86/arch/x86/platform/efi/quirks.c > > > @@ -260,10 +260,6 @@ 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; > > > - > > > size += addr % EFI_PAGE_SIZE; > > > size = round_up(size, EFI_PAGE_SIZE); > > > addr = round_down(addr, EFI_PAGE_SIZE); > > > @@ -293,6 +289,8 @@ void __init efi_arch_mem_reserve(phys_ad > > > early_memunmap(new, new_size); > > > > > > efi_memmap_install(new_phys, num_entries); > > > + e820__range_update(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVED); > > > + e820__update_table(e820_table); > > > } > > > > > > /* > > > > > > > Bisect says this change (commit af1648984828) is triggering a > > regression, likely not urgent, in my testing of the new efi_fake_mem= > > facility to allow memory to be marked "soft reserved" via the kernel > > command line (commit 199c84717612 x86/efi: Add efi_fake_mem support > > for EFI_MEMORY_SP). The following command line triggers the crash > > signature below: > > > > efi_fake_mem=4G@9G:0x40000,4G@13G:0x40000 > > > > However, this command line works ok: > > > > efi_fake_mem=8G@9G:0x40000 > > > > So, something about multiple efi_fake_mem statements interacts badly > > with this change. Nothing obvious occurs to me at the moment, I'll > > keep debugging, but wanted to highlight this in the meantime in case > > someone else sees a deeper issue or the root cause. > > Still looking, but this failure does not seem to be specific to the > "soft reservation" changes. Any update to the efi memmap that pushes > it over a page boundary triggers this failure. I.e. I can fix the > problem by over-allocating the efi memmap and then page aligning the > result. __early_ioremap "should" be handling this case, but it appears > something else is messing this up. I seems can not reproduce the bug, but maybe my vm setup is different. Can you do some debugging about the efi_memmap_insert function see if something wrong happened, maybe happens when memcpy to some new allocated buffer via memblock_alloc, just some guess. Thanks Dave _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec