linux-kernel - Re: [PATCH V5] efi/tpm: Fix the issue where the CC platforms event log header can't be correctly identified

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Message-ID: <f43764cd-597b-487f-878b-a071df12f414@126.com>
Date: Sat, 12 Jul 2025 11:24:25 +0800
From: Ge Yang <yangge1116@....com>
To: James Bottomley <James.Bottomley@...senPartnership.com>, ardb@...nel.org
Cc: jarkko@...nel.org, sathyanarayanan.kuppuswamy@...ux.intel.com,
 ilias.apalodimas@...aro.org, jgg@...pe.ca, linux-efi@...r.kernel.org,
 linux-kernel@...r.kernel.org, stable@...r.kernel.org, liuzixing@...on.cn
Subject: Re: [PATCH V5] efi/tpm: Fix the issue where the CC platforms event
 log header can't be correctly identified



在 2025/7/12 11:03, James Bottomley 写道:
> On Sat, 2025-07-12 at 10:55 +0800, yangge1116@....com wrote:
>> From: Ge Yang <yangge1116@....com>
>>
>> Since commit d228814b1913 ("efi/libstub: Add get_event_log() support
>> for CC platforms") reuses TPM2 support code for the CC platforms,
>> when launching a TDX virtual machine with coco measurement enabled,
>> the following error log is generated:
>>
>> [Firmware Bug]: Failed to parse event in TPM Final Events Log
>>
>> Call Trace:
>> efi_config_parse_tables()
>>    efi_tpm_eventlog_init()
>>      tpm2_calc_event_log_size()
>>        __calc_tpm2_event_size()
>>
>> The pcr_idx value in the Intel TDX log header is 1, causing the
>> function __calc_tpm2_event_size() to fail to recognize the log
>> header, ultimately leading to the "Failed to parse event in TPM Final
>> Events Log" error.
>>
>> According to UEFI Specification 2.10, Section 38.4.1: For TDX, TPM
>> PCR 0 maps to MRTD, so the log header uses TPM PCR 1 instead.
> 
> This isn't a justification ... Intel just screwed up.  Whatever the
> UEFI spec says about PCR mapping, the log spec the TCG produces
> requires the header event to have a pcrIndex of 0 and, since it isn't
> recorded in a PCR, it doesn't matter what the mapping is.
> 
> Just say Intel misread the spec and wrongly sets pcrIndex to 1 in the
> header and since they did this, we fear others might, so we're relaxing
> the header check.
> 

OK, thanks.


> Regards,
> 
> James