linux-kernel - Re: [PATCH v2 1/2] crypto: ccp - Initialize PSP when reading psp data file failed

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Message-ID: <8feee515-8d60-dc84-4c9f-6723481e8dac@google.com>
Date:   Tue, 16 Aug 2022 14:25:02 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Jacky Li <jackyli@...gle.com>
cc:     Brijesh Singh <brijesh.singh@....com>,
        Tom Lendacky <thomas.lendacky@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>,
        Marc Orr <marcorr@...gle.com>, Alper Gun <alpergun@...gle.com>,
        Peter Gonda <pgonda@...gle.com>, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] crypto: ccp - Initialize PSP when reading psp
 data file failed

On Tue, 16 Aug 2022, Jacky Li wrote:

> Currently the OS fails the PSP initialization when the file specified at
> 'init_ex_path' does not exist or has invalid content. However the SEV
> spec just requires users to allocate 32KB of 0xFF in the file, which can
> be taken care of by the OS easily.
> 
> To improve the robustness during the PSP init, leverage the retry
> mechanism and continue the init process:
> 
> Before the first INIT_EX call, if the content is invalid or missing,
> continue the process by feeding those contents into PSP instead of
> aborting. PSP will then override it with 32KB 0xFF and return
> SEV_RET_SECURE_DATA_INVALID status code. In the second INIT_EX call,
> this 32KB 0xFF content will then be fed and PSP will write the valid
> data to the file.
> 
> In order to do this, sev_read_init_ex_file should only be called once
> for the first INIT_EX call. Calling it again for the second INIT_EX call
> will cause the invalid file content overwriting the valid 32KB 0xFF data
> provided by PSP in the first INIT_EX call.
> 
> Co-developed-by: Peter Gonda <pgonda@...gle.com>
> Signed-off-by: Peter Gonda <pgonda@...gle.com>
> Signed-off-by: Jacky Li <jackyli@...gle.com>
> Reported-by: Alper Gun <alpergun@...gle.com>

Acked-by: David Rientjes <rientjes@...gle.com>