linux-kernel - Re: [PATCH] crypto: ccp - Retry SEV INIT command in case of integrity check failure.

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Date:   Sat, 19 Oct 2019 01:59:02 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     "Kalra, Ashish" <Ashish.Kalra@....com>
cc:     "Lendacky, Thomas" <Thomas.Lendacky@....com>,
        "Hook, Gary" <Gary.Hook@....com>,
        "herbert@...dor.apana.org.au" <herbert@...dor.apana.org.au>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "allison@...utok.net" <allison@...utok.net>,
        "info@...ux.net" <info@...ux.net>,
        "yamada.masahiro@...ionext.com" <yamada.masahiro@...ionext.com>,
        "Singh, Brijesh" <brijesh.singh@....com>,
        "linux-crypto@...r.kernel.org" <linux-crypto@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>
Subject: Re: [PATCH] crypto: ccp - Retry SEV INIT command in case of integrity
 check failure.

On Thu, 17 Oct 2019, Kalra, Ashish wrote:

> From: Ashish Kalra <ashish.kalra@....com>
> 
> SEV INIT command loads the SEV related persistent data from NVS
> and initializes the platform context. The firmware validates the
> persistent state. If validation fails, the firmware will reset
> the persisent state and return an integrity check failure status.
> 
> At this point, a subsequent INIT command should succeed, so retry
> the command. The INIT command retry is only done during driver
> initialization.
> 
> Additional enums along with SEV_RET_SECURE_DATA_INVALID are added
> to sev_ret_code to maintain continuity and relevance of enum values.
> 
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> ---
>  drivers/crypto/ccp/psp-dev.c | 12 ++++++++++++
>  include/uapi/linux/psp-sev.h |  3 +++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/drivers/crypto/ccp/psp-dev.c b/drivers/crypto/ccp/psp-dev.c
> index 6b17d179ef8a..f9318d4482f2 100644
> --- a/drivers/crypto/ccp/psp-dev.c
> +++ b/drivers/crypto/ccp/psp-dev.c
> @@ -1064,6 +1064,18 @@ void psp_pci_init(void)
>  
>  	/* Initialize the platform */
>  	rc = sev_platform_init(&error);
> +	if (rc && (error == SEV_RET_SECURE_DATA_INVALID)) {
> +		/*
> +		 * INIT command returned an integrity check failure
> +		 * status code, meaning that firmware load and
> +		 * validation of SEV related persistent data has
> +		 * failed and persistent state has been erased.
> +		 * Retrying INIT command here should succeed.
> +		 */
> +		dev_dbg(sp->dev, "SEV: retrying INIT command");
> +		rc = sev_platform_init(&error);
> +	}
> +
>  	if (rc) {
>  		dev_err(sp->dev, "SEV: failed to INIT error %#x\n", error);
>  		return;

Curious why this isn't done in __sev_platform_init_locked() since 
sev_platform_init() can be called when loading the kvm module and the same 
init failure can happen that way.

> diff --git a/include/uapi/linux/psp-sev.h b/include/uapi/linux/psp-sev.h
> index 8654b2442f6a..a8537f4e5e08 100644
> --- a/include/uapi/linux/psp-sev.h
> +++ b/include/uapi/linux/psp-sev.h
> @@ -58,6 +58,9 @@ typedef enum {
>  	SEV_RET_HWSEV_RET_PLATFORM,
>  	SEV_RET_HWSEV_RET_UNSAFE,
>  	SEV_RET_UNSUPPORTED,
> +	SEV_RET_INVALID_PARAM,
> +	SEV_RET_RESOURCE_LIMIT,
> +	SEV_RET_SECURE_DATA_INVALID,
>  	SEV_RET_MAX,
>  } sev_ret_code;
>