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 12:44:51 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Borislav Petkov <bp@...en8.de>
Cc:     fanc.fnst@...fujitsu.com, 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 08:10:24PM +0100, Borislav Petkov wrote:
> 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() ?
> 
Yes, the kernel boots if I comment out that function and have it return 0.

Guenter

> Chao, pls take a look.
> 
> Thx.
> 
> -- 
> Regards/Gruss,
>     Boris.
> 
> Good mailing practices for 400: avoid top-posting and trim the reply.