Re: [RFC PATCH 1/4] tee: Re-enable vmalloc page support for shared memory

[Arnaud POULIQUEN <arnaud.pouliquen@foss.st.com>]

On 5/26/23 14:37, Christoph Hellwig wrote:
> On Wed, May 24, 2023 at 04:01:14PM +0200, Arnaud POULIQUEN wrote:
>>> As per the discussion back then: don't just blindly do the same dumb
>>> thing again and fix the interfae to actually pass in a page array,
>>> or iov_iter or an actually useful container that fits.
>>>
>>
>> I suppose your are speaking about this discussion:
>> https://lore.kernel.org/all/20221002002326.946620-3-ira.weiny@intel.com/
> 
> Yes.
> 
>>
>> If I'm not mistaken, I should modify at tee_shm_register_kernel_buf API and
>> register_shm_helper inernal function, right?
>>
> 
>> What about having equivalent of shm_get_kernel_pages in an external helper (to
>> defined where to put it), could it be an alternative of the upadate of the
>> tee_shm API?
> 
> I think the fundamentally right thing is to pass an iov_iter to
> register_shm_helper, and then use the new as of 6.3
> iov_iter_extract_pages helper to extract the pages from that.  For
> the kernel users you can then simply pass down an ITER_BVEC iter
> that you can fill with vmalloc pages if you want.
> 

Thanks for the advice!

Regards,
Arnaud