lkml.org 
[lkml]   [2017]   [Mar]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4] tpm_crb: request and relinquish locality 0
On Fri, Mar 24, 2017 at 12:10:30PM +0200, Jarkko Sakkinen wrote:
> This commit adds support for requesting and relinquishing locality 0 in
> tpm_crb for the course of command transmission.
>
> In order to achieve this, two new callbacks are added to struct
> tpm_class_ops:
>
> - request_locality
> - relinquish_locality
>
> With CRB interface you first set either requestAccess or relinquish bit
> from TPM_LOC_CTRL_x register and then wait for locAssigned and
> tpmRegValidSts bits to be set in the TPM_LOC_STATE_x register.
>
> The reason why were are doing this is to make sure that the driver
> will work properly with Intel TXT that uses locality 2. There's no
> explicit guarantee that it would relinquish this locality. In more
> general sense this commit enables tpm_crb to be a well behaving
> citizen in a multi locality environment.
>
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
> v2:
> - TPM driver level calllbacks
> v3:
> - Call ops->relinquish_locality only if ops->request_locality has been
> successful.
> - Do not reserve locality in nested tpm_transmit calls.
> - Check for tpmRegValidSts to make sure that the value in TPM_LOC_STATE_x is
> stable.
> v4:
> - Removed tpm_tis_core changes. It needs to be done separately. It will be
> postponed to 4.13.
> - Store locality to struct tpm_chip while active.
> drivers/char/tpm/tpm-chip.c | 1 +
> drivers/char/tpm/tpm-interface.c | 13 +++++++++++++
> drivers/char/tpm/tpm.h | 3 +++
> drivers/char/tpm/tpm_crb.c | 41 ++++++++++++++++++++++++++++++++++++++++
> include/linux/tpm.h | 3 ++-
> 5 files changed, 60 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
> index aade699..a321bd5 100644
> --- a/drivers/char/tpm/tpm-chip.c
> +++ b/drivers/char/tpm/tpm-chip.c
> @@ -231,6 +231,7 @@ struct tpm_chip *tpm_chip_alloc(struct device *pdev,
> goto out;
> }
>
> + chip->locality = -1;
> return chip;
>
> out:
> diff --git a/drivers/char/tpm/tpm-interface.c b/drivers/char/tpm/tpm-interface.c
> index 95c6f98..1815666 100644
> --- a/drivers/char/tpm/tpm-interface.c
> +++ b/drivers/char/tpm/tpm-interface.c
> @@ -384,6 +384,7 @@ ssize_t tpm_transmit(struct tpm_chip *chip, struct tpm_space *space,
> ssize_t len = 0;
> u32 count, ordinal;
> unsigned long stop;
> + bool need_locality = chip->locality == -1;

This must be set *after* taking the mutex. Otherwise, I think this
should be fine now.

/Jarkko

\
 
 \ /
  Last update: 2017-03-24 11:19    [W:0.099 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site