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 1iconm-0006Yc-As for kexec@lists.infradead.org; Thu, 05 Dec 2019 10:56:08 +0000 Date: Thu, 5 Dec 2019 18:55:45 +0800 From: Dave Young Subject: Re: [PATCH] x86/efi: update e820 about reserved EFI boot services data to fix kexec breakage Message-ID: <20191205105545.GA6710@dhcp-128-65.nay.redhat.com> References: <20191204075233.GA10520@dhcp-128-65.nay.redhat.com> <20191204075917.GA10587@dhcp-128-65.nay.redhat.com> <20191204101412.GD114697@gmail.com> MIME-Version: 1.0 In-Reply-To: <20191204101412.GD114697@gmail.com> Content-Disposition: inline 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: Ingo Molnar Cc: Michael Weiser , linux-efi@vger.kernel.org, Ard Biesheuvel , x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Ingo Molnar , Borislav Petkov , "Eric W. Biederman" , "H. Peter Anvin" , Thomas Gleixner On 12/04/19 at 11:14am, Ingo Molnar wrote: > > * Dave Young wrote: > > > On 12/04/19 at 03:52pm, 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. > > > > s/overwritten/overwrote :) If need a repost please let me know.. > > > > > > > > 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 > > > So I edited this to: > > From: Dave Young > > Michael Weiser reported he got this 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 the X86 E820 table, > and kexec_file_load() iterates system RAM in the IO resource list to find places > for kernel, initramfs and other stuff. In Michael's case the kexec loaded > initramfs overwrote the ESRT memory and then the failure happened. > > Since kexec_file_load() depends on the E820 table being 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 reboots, > 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. > Thanks for the amending, also thank all for the review and test. Dave _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec