linux-kernel - Re: ibmvtpm byteswapping inconsistency

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Date:   Wed, 1 Feb 2017 23:40:33 -0500
From:   Vicky <honclo@...ux.vnet.ibm.com>
To:     Ashley Lai <ashleydlai@...il.com>
Cc:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        Michal Such??nek <msuchanek@...e.de>,
        Nayna Jain <nayna@...ux.vnet.ibm.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Peter Huewe <peterhuewe@....de>,
        Marcel Selhorst <tpmdd@...horst.net>,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        tpmdd-devel@...ts.sourceforge.net, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: Re: ibmvtpm byteswapping inconsistency


> On Jan 26, 2017, at 5:58 PM, Ashley Lai <ashleydlai@...il.com> wrote:
> 
> Adding Vicky from IBM.
> 
> 
> On 01/26/2017 04:05 PM, Jason Gunthorpe wrote:
>> On Thu, Jan 26, 2017 at 09:22:48PM +0100, Michal Such??nek wrote:
>> 
>>> This is repeated a few times in the driver so I added memset to quiet
>>> gcc and make behavior deterministic in case the unused fields get some
>>> meaning in the future.
>> Yep, reserved certainly needs to be zeroed.. Can you send a patch?
>> memset is overkill...
>> 
>>> However, in tpm_ibmvtpm_send the structure is initialized as
>>> 
>>> 	struct ibmvtpm_crq crq;
>>>         __be64 *word = (__be64 *)&crq;
>>> ...
>>>         crq.valid = (u8)IBMVTPM_VALID_CMD;
>>>         crq.msg = (u8)VTPM_TPM_COMMAND;
>>>         crq.len = cpu_to_be16(count);
>>>         crq.data = cpu_to_be32(ibmvtpm->rtce_dma_handle);
>>> 
>>> and submitted with
>>> 
>>> 	rc = ibmvtpm_send_crq(ibmvtpm->vdev, be64_to_cpu(word[0]),
>>>                               be64_to_cpu(word[1]));
>>> meaning it is swapped twice.
>> No idea, Nayna may know.
>> 
>> My guess is that '__be64 *word' should be 'u64 *word'...
>> 
>> Jason
> 

I don’t think we want ‘word' to be changed back to be of type ‘u64’.   Please see commit 62dfd912ab3b5405b6fe72d0135c37e9648071f1


Vicky