linux-kernel - Re: [PATCH v7] tpm: cmd_ready command can be issued only after granting locality

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Date:   Mon, 5 Mar 2018 19:51:29 +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 v7] tpm: cmd_ready command can be issued only after
 granting locality

On Mon, Mar 05, 2018 at 01:34:49PM +0200, Tomas Winkler wrote:
> The correct sequence is to first request locality and only after
> that perform cmd_ready handshake, otherwise the hardware will drop
> the subsequent message as from the device point of view the cmd_ready
> handshake wasn't performed. Symmetrically locality has to be relinquished
> only after going idle handshake has completed, this requires that
> go_idle has to poll for the completion and as well locality
> relinquish has to poll for completion so it is not overridden
> in back to back commands flow.
> 
> Two wrapper functions are added (request_locality relinquish_locality)
> to simplify the error handling.
> 
> The issue is only visible on devices that support multiple localities.
> 
> Fixes: 877c57d0d0ca ("tpm_crb: request and relinquish locality 0")
> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>

Tested-by: Jarkko Sakkinen <jarkko.sakkine@...ux.intel.com>
Reviewed-by: Jarkko Sakkinen <jarkko.sakkine@...ux.intel.com>

/Jarkko