Thread (23 messages) 23 messages, 9 authors, 2017-02-02

Re: ibmvtpm byteswapping inconsistency

From: Ashley Lai <hidden>
Date: 2017-01-26 22:58:26
Also in: lkml

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:
quoted
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...
quoted
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
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