linux-kernel - Re: [PATCH 1/3 RESEND] tpm: add longer timeouts for creation commands.

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Date:   Mon, 5 Mar 2018 14:56:42 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Tomas Winkler <tomas.winkler@...el.com>
Cc:     Jason Gunthorpe <jgg@...pe.ca>,
        Alexander Usyskin <alexander.usyskin@...el.com>,
        linux-integrity@...r.kernel.org,
        linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3 RESEND] tpm: add longer timeouts for creation
 commands.

On Sun, Mar 04, 2018 at 02:12:03PM +0200, Tomas Winkler wrote:
> TPM2_CC_Create(0x153) and TPM2_CC_CreatePrimary (0x131) involve generation
> of crypto keys which can be a computationally intensive task.
> The timeout is set to 3min.
> 
> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>

Where is the cover letter? Please send separate patches if they are
unrelated *or* add a cover letter that describes what they do as a
whole.

I will not review the next version if it does not have cover letter
describing the high level change and containing the change log.

> ---
>  drivers/char/tpm/tpm-interface.c |  4 ++++
>  drivers/char/tpm/tpm.h           | 27 ++++++++++++++++-----------
>  drivers/char/tpm/tpm2-cmd.c      |  8 +++++---
>  3 files changed, 25 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 85bdfa8c3348..c0aa9d11ec7a 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -699,6 +699,10 @@ int tpm_get_timeouts(struct tpm_chip *chip)
>  		    msecs_to_jiffies(TPM2_DURATION_MEDIUM);
>  		chip->duration[TPM_LONG] =
>  		    msecs_to_jiffies(TPM2_DURATION_LONG);
> +		chip->duration[TPM_LONG_LONG] =
> +		    msecs_to_jiffies(TPM2_DURATION_LONG_LONG);
> +		chip->duration[TPM_UNDEFINED] =
> +		    msecs_to_jiffies(TPM2_DURATION_DEFAULT);
>  
>  		chip->flags |= TPM_CHIP_FLAG_HAVE_TIMEOUTS;
>  		return 0;
> diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
> index f895fba4e20d..192ba68b39c2 100644
> --- a/drivers/char/tpm/tpm.h
> +++ b/drivers/char/tpm/tpm.h
> @@ -67,7 +67,9 @@ enum tpm_duration {
>  	TPM_SHORT = 0,
>  	TPM_MEDIUM = 1,
>  	TPM_LONG = 2,
> -	TPM_UNDEFINED,
> +	TPM_LONG_LONG = 3,
> +	TPM_UNDEFINED = 4,
> +	TPM_DURATION_MAX,

This is starting to rotten to become unmaintainable.

Here is what I suggest to move forward:

* Have essentially two duration types:
  1. Default
  2. Long
  'default' is the old long duration i.e. two seconds. 'long' is a

We should probably have two durations:

enum tpm_duration {
	TPM_DURATION_DEFAULT = 2000,
	TPM_DURATION_LONG = 300000,
};

These would be both for TPM 1.2 and TPM 2.0. Instead of having
table for every ordinal there should be a small tables describing
commands that require long timeout.

> -		duration = 2 * 60 * HZ;
> +		duration = msecs_to_jiffies(TPM2_DURATION_DEFAULT);

NAK for this change.

/Jarkko