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 11:02:48 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     tglx@...utronix.de, linux-kernel@...r.kernel.org,
        kirill.shutemov@...ux.intel.com, bp@...e.de,
        fanc.fnst@...fujitsu.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
Cc:     linux-tip-commits@...r.kernel.org
Subject: Re: [tip:x86/boot] x86/boot: Early parse RSDP and save it in
 boot_params

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.

Bisect log attached below.

Guenter

---
# bad: [a46228f6598a191e25ca160870f20c3cd1743d13] Add linux-next specific files for 20190208
# good: [8834f5600cf3c8db365e18a3d5cac2c2780c81e5] Linux 5.0-rc5
git bisect start 'HEAD' 'v5.0-rc5'
# good: [d5ee02f33ec5ade9c9afb9d45bfc4f5cb1375e58] Merge remote-tracking branch 'spi-nor/spi-nor/next'
git bisect good d5ee02f33ec5ade9c9afb9d45bfc4f5cb1375e58
# good: [f34bff29873986d260d7a491fb6f543d12fbe7cd] Merge remote-tracking branch 'devicetree/for-next'
git bisect good f34bff29873986d260d7a491fb6f543d12fbe7cd
# bad: [68182cb929ec6a676655887cbfb12b09662c1e5b] Merge remote-tracking branch 'icc/icc-next'
git bisect bad 68182cb929ec6a676655887cbfb12b09662c1e5b
# bad: [0a5c6189664123753c298d90dec3a5a6b907f06f] Merge remote-tracking branch 'driver-core/driver-core-next'
git bisect bad 0a5c6189664123753c298d90dec3a5a6b907f06f
# bad: [e2a43b09bfc24369719437b5f8f703c5d7003af2] Merge remote-tracking branch 'tip/auto-latest'
git bisect bad e2a43b09bfc24369719437b5f8f703c5d7003af2
# good: [ba1ef96ac73d2a9851dc64d0a991ac8699aa6a22] Merge branch 'timers/core'
git bisect good ba1ef96ac73d2a9851dc64d0a991ac8699aa6a22
# good: [473a78a7bbeb7c77b81b596095f59ce4fbbd49dc] spi-atmel: support inter-word delay
git bisect good 473a78a7bbeb7c77b81b596095f59ce4fbbd49dc
# bad: [132dc31173c99bd252f6a54e3a9fba90f7417a43] Merge branch 'x86/cleanups'
git bisect bad 132dc31173c99bd252f6a54e3a9fba90f7417a43
# bad: [6eb09d138a331121740a4cf7458ab317979d9a17] Merge branch 'x86/boot'
git bisect bad 6eb09d138a331121740a4cf7458ab317979d9a17
# good: [e2c403557ebbcd1f0052e1ae51cfaff596cf259d] Merge branch 'x86/asm'
git bisect good e2c403557ebbcd1f0052e1ae51cfaff596cf259d
# good: [33f0df8d843deb9ec24116dcd79a40ca0ea8e8a9] x86/boot: Search for RSDP in the EFI tables
git bisect good 33f0df8d843deb9ec24116dcd79a40ca0ea8e8a9
# bad: [3a63f70bf4c3a17f5d9c9bf3bc3288a23bdfefce] x86/boot: Early parse RSDP and save it in boot_params
git bisect bad 3a63f70bf4c3a17f5d9c9bf3bc3288a23bdfefce
# good: [93a209aaaad495d7d0bc9b6186a4495934f70402] x86/boot: Search for RSDP in memory
git bisect good 93a209aaaad495d7d0bc9b6186a4495934f70402
# first bad commit: [3a63f70bf4c3a17f5d9c9bf3bc3288a23bdfefce] x86/boot: Early parse RSDP and save it in boot_params