linux-kernel - Re: ibmvtpm byteswapping inconsistency

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Message-ID: <024dadba-a75c-ab59-9d12-a9bea81f9bda@gmail.com>
Date:   Thu, 26 Jan 2017 16:58:15 -0600
From:   Ashley Lai <ashleydlai@...il.com>
To:     Jason Gunthorpe <jgunthorpe@...idianresearch.com>,
        Michal Such??nek <msuchanek@...e.de>,
        Nayna Jain <nayna@...ux.vnet.ibm.com>,
        honclo@...ux.vnet.ibm.com
Cc:     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

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