linux-kernel - Re: [tip:x86/boot] x86/boot: Early parse RSDP and save it in boot

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Date:   Fri, 8 Feb 2019 20:10:24 +0100
From:   Borislav Petkov <bp@...en8.de>
To:     Guenter Roeck <linux@...ck-us.net>, fanc.fnst@...fujitsu.com
Cc:     tglx@...utronix.de, linux-kernel@...r.kernel.org,
        kirill.shutemov@...ux.intel.com, mingo@...hat.com,
        thomas.lendacky@....com, yamada.masahiro@...ionext.com,
        caoj.fnst@...fujitsu.com, jgross@...e.com, mingo@...nel.org,
        keescook@...omium.org, x86@...nel.org, hpa@...or.com,
        linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/boot] x86/boot: Early parse RSDP and save it in
 boot_params

On Fri, Feb 08, 2019 at 11:02:48AM -0800, Guenter Roeck wrote:
> Hi,
> 
> On Fri, Feb 01, 2019 at 03:01:11AM -0800, tip-bot for Chao Fan wrote:
> > Commit-ID:  3a63f70bf4c3a17f5d9c9bf3bc3288a23bdfefce
> > Gitweb:     https://git.kernel.org/tip/3a63f70bf4c3a17f5d9c9bf3bc3288a23bdfefce
> > Author:     Chao Fan <fanc.fnst@...fujitsu.com>
> > AuthorDate: Wed, 23 Jan 2019 19:08:48 +0800
> > Committer:  Borislav Petkov <bp@...e.de>
> > CommitDate: Fri, 1 Feb 2019 11:52:55 +0100
> > 
> > x86/boot: Early parse RSDP and save it in boot_params
> > 
> > The RSDP is needed by KASLR so parse it early and save it in
> > boot_params.acpi_rsdp_addr, before KASLR setup runs.
> > 
> > RSDP is needed by other kernel facilities so have the parsing code
> > built-in instead of a long "depends on" line in Kconfig.
> > 
> >  [ bp:
> >     - Trim commit message and comments
> >     - Add CONFIG_ACPI dependency in the Makefile
> >     - Move ->acpi_rsdp_addr assignment with the rest of boot_params massaging in extract_kernel().
> >  ]
> > 
> 
> This patch causes x86_64 boots with efi32 bios to crash early and hard
> (before any console output is seen).
> 
> Sample qemu command line:
> 
> qemu-system-x86_64 -kernel arch/x86/boot/bzImage -M q35 -cpu SandyBridge \
> 	-no-reboot -snapshot -smp 4 \
> 	-bios OVMF-pure-efi-32.fd \
> 	-m 1G \
> 	-usb -device usb-storage,drive=d0 \
> 	-drive file=rootfs.squashfs,if=none,id=d0,format=raw \
> 	--append 'earlycon=uart8250,io,0x3f8,9600n8 root=/dev/sda rootwait panic=-1 console=ttyS0' \
> 	-nographic
> 
> This is with qemu 3.1, though details other than "-bios OVMF-pure-efi-32.fd"
> don't really matter.
> 
> Files used above are available from https://github.com/groeck/linux-build-test/.
> 
> The patch can not be reverted alone, but
> 
> Revert "x86/boot/KASLR: Limit KASLR to extract the kernel in immovable memory only"
> Revert "x86/boot: Parse SRAT table and count immovable memory regions"
> Revert "x86/boot: Early parse RSDP and save it in boot_params"
> 
> fixes the problem.

Does it per chance at least continue booting if you return 0 and early
from efi_get_rsdp_addr() ?

Chao, pls take a look.

Thx.

-- 
Regards/Gruss,
    Boris.

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