linux-kernel - Re: [PATCH v4] crypto: ccp: Sanitize sev_platform

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Message-ID: <ddbb4b2f-3eb8-64da-bce9-3cfd66d7729a@amd.com>
Date:   Tue, 10 Jan 2023 08:41:33 -0600
From:   Tom Lendacky <thomas.lendacky@....com>
To:     Jarkko Sakkinen <jarkko@...fian.com>,
        Brijesh Singh <brijesh.singh@....com>,
        John Allen <john.allen@....com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        "David S. Miller" <davem@...emloft.net>
Cc:     "open list:AMD CRYPTOGRAPHIC COPROCESSOR (CCP) DRIVER - SE..." 
        <linux-crypto@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] crypto: ccp: Sanitize sev_platform_init() error
 messages

On 1/9/23 21:35, Jarkko Sakkinen wrote:
> The following functions end up calling sev_platform_init() or
> __sev_platform_init_locked():
> 
> * sev_guest_init()
> * sev_ioctl_do_pek_csr
> * sev_ioctl_do_pdh_export()
> * sev_ioctl_do_pek_import()
> * sev_ioctl_do_pek_pdh_gen()
> * sev_pci_init()
> 
> However, only sev_pci_init() prints out the failed command error code, and
> even there, the error message does not specify which SEV command failed.
> 
> Address this by printing out the SEV command errors inside
> __sev_platform_init_locked(), and differentiate between DF_FLUSH, INIT and
> INIT_EX commands.  As a side-effect, @error can be removed from the
> parameter list.
> 
> This extra information is particularly useful if firmware loading and/or
> initialization is going to be made more robust, e.g. by allowing firmware
> loading to be postponed.
> ---
> v4:
> * Sorry, v3 was malformed. Here's a proper patch.
> 
> v3:
> * Address Tom Lendacky's feedback:
>    https://lore.kernel.org/kvm/8bf6f179-eee7-fd86-7892-cdcd76e0762a@amd.com/
> 
> v2:
> * Address David Rientjes's feedback:
>    https://lore.kernel.org/all/6a16bbe4-4281-fb28-78c4-4ec44c8aa679@google.com/
> * Remove @error.
> * Remove "SEV_" prefix: it is obvious from context so no need to make klog
>    line longer.
> 
> Signed-off-by: Jarkko Sakkinen <jarkko@...fian.com>
> ---
>   drivers/crypto/ccp/sev-dev.c | 17 ++++++++++-------
>   1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
> index 06fc7156c04f..bdc43e75c78b 100644
> --- a/drivers/crypto/ccp/sev-dev.c
> +++ b/drivers/crypto/ccp/sev-dev.c
> @@ -476,19 +476,23 @@ static int __sev_platform_init_locked(int *error)
>   		dev_err(sev->dev, "SEV: retrying INIT command because of SECURE_DATA_INVALID error. Retrying once to reset PSP SEV state.");
>   		rc = init_function(&psp_ret);
>   	}
> -	if (error)
> +	if (rc) {
> +		dev_err(sev->dev, "SEV: %s failed error %#x",
> +			sev_init_ex_buffer ? "CMD_INIT_EX" : "CMD_INIT", psp_ret);
>   		*error = psp_ret;

If I'm not mistaken, error can be NULL, that's why the "if (error)" was 
present. So that should be kept and even filled in on success. So please 
leave it the way it was and just add the message to the "if (rc)" section.

> -
> -	if (rc)
>   		return rc;
> +	}
>   
>   	sev->state = SEV_STATE_INIT;
>   
>   	/* Prepare for first SEV guest launch after INIT */
>   	wbinvd_on_all_cpus();
> -	rc = __sev_do_cmd_locked(SEV_CMD_DF_FLUSH, NULL, error);
> -	if (rc)
> +	rc = __sev_do_cmd_locked(SEV_CMD_DF_FLUSH, NULL, &psp_ret);

Same here, add:

	if (error)
		*error = psp_ret;

Thanks,
Tom

> +	if (rc) {
> +		dev_err(sev->dev, "SEV: CMD_DF_FLUSH failed error %#x", psp_ret);
> +		*error = psp_ret;
>   		return rc;
> +	}
>   
>   	dev_dbg(sev->dev, "SEV firmware initialized\n");
>   
> @@ -1337,8 +1341,7 @@ void sev_pci_init(void)
>   	/* Initialize the platform */
>   	rc = sev_platform_init(&error);
>   	if (rc)
> -		dev_err(sev->dev, "SEV: failed to INIT error %#x, rc %d\n",
> -			error, rc);
> +		dev_err(sev->dev, "SEV: failed to INIT rc %d\n", rc);
>   
>   	return;
>