Re: [PATCH 0/2] Map initrd as encrypted when relocating if SME is enabled

[Zelin Deng <zelin.deng@linux.alibaba.com>]

在 2022/11/24 22:26, Tom Lendacky 写道:
> On 11/24/22 03:12, Zelin Deng wrote:
>> I found an issue on SME enabled AMD machine when initrd is relocated if
>> it was located in e820 reserved area.
>> For example key dmesg output:
>> ...
>> [mem 0x000000005aafe000-0x000000006005ffff] reserved //e820 mapping
>> Move RAMDISK from [mem 0x5aafe000-0x5ccd5167] //relocate_initrd()
>> ...
>>
>> Early initrd will be copied by copy_from_early_mem() which will clear
>> encrypted pgprot flag as initrd source address is not in kernel usable
>> area. As initrd has been encrypted at earlier stage, encrypted data is
>> copied, which leads new initrd cannot be unpacked, then rootfs cannot be
>> mounted.
>
> This is actually a bug in Grub where the kernel and initrd was moved 
> out of loader_code/data and into runtime_service_code/data. This 
> commit has since been reverted because it goes against the UEFI 
> specification. It was a small window, but the bad version was picked 
> up by some distros. No need for a kernel change, please update your 
> version of Grub.
>
> Thanks,
> Tom
>
Hi Tom,

Thank you for clarification, I will update my grub and try again.

Thanks,

Zelin Deng

>> dmesg output:
>> ...
>> [   11.296725] Trying to unpack rootfs image as initramfs...
>> [   11.302127] Initramfs unpacking failed: invalid magic at start of 
>> compressed archive
>> ...
>> [   16.698152] /dev/root: Can't open blockdev
>> [   16.702255] VFS: Cannot open root device 
>> "PARTUUID=0ad58d87-05c7-43f8-b147-93140ad315e5" or 
>> unknown-block(0,0): error -6
>> [   16.713114] Please append a correct "root=" boot option; here are 
>> the available partitions:
>> [   16.721462] Kernel panic - not syncing: VFS: Unable to mount root 
>> fs on unknown-block(0,0)
>> [   16.729716] CPU: 9 PID: 1 Comm: swapper/0 Not tainted 
>> 6.1.0-rc5-next-20221114 #3
>> [   16.737099] Hardware name: AMD Corporation DAYTONA_X/DAYTONA_X, 
>> BIOS RYM1008B 01/19/2022
>> [   16.745175] Call Trace:
>> [   16.747623]  <TASK>
>> [   16.749727]  dump_stack_lvl+0x38/0x4c
>> [   16.753393]  panic+0xfb/0x28a
>> [   16.771999]  ? _printk+0x4c/0x52
>> [   16.775224]  mount_block_root+0x143/0x1dd
>> [   16.779237]  prepare_namespace+0x13f/0x16e
>> [   16.783334]  kernel_init_freeable+0x15a/0x164
>> [   16.787687]  ? __pfx_kernel_init+0x10/0x10
>> [   16.791785]  kernel_init+0x1a/0x130
>> [   16.795268]  ret_from_fork+0x29/0x50
>> [   16.798840]  </TASK>
>>
>> To fix this issue, early initrd must be mapped as encrypted when it is
>> being relocated.
>>
>> Zelin Deng (2):
>>    mm/early_ioremap.c: Always build early_memremap_prot() in x86
>>    x86/setup: Preserve _ENC flag when initrd is being relocated
>>
>>   arch/x86/Kconfig                    |  1 +
>>   arch/x86/kernel/setup.c             | 30 ++++++++++++++++++++++++++++-
>>   include/asm-generic/early_ioremap.h |  6 ------
>>   mm/early_ioremap.c                  | 21 --------------------
>>   4 files changed, 30 insertions(+), 28 deletions(-)
>>