Re: [Xen-devel] [PATCH v3 1/3] xen/arm: optee: handle shared buffer translation error

[Julien Grall <julien.grall@xxxxxxx>]

Hi Volodymyr,

On 9/24/19 4:46 PM, Volodymyr Babchuk wrote:
> There is a case possible, when OP-TEE asks guest to allocate shared
> buffer, but Xen for some reason can't translate buffer's addresses. In
> this situation we should do two things:
>
> 1. Tell guest to free allocated buffer, so there will be no memory
> leak for guest.
>
> 2. Tell OP-TEE that buffer allocation failed.
>
> To ask guest to free allocated buffer we should perform the same
> thing, as OP-TEE does - issue RPC request. This is done by filling
> request buffer (luckily we can reuse the same buffer, that OP-TEE used
> to issue original request) and then return to guest with special
> return code.
>
> Then we need to handle next call from guest in a special way: as RPC
> was issued by Xen, not by OP-TEE, it should be handled by Xen.
> Basically, this is the mechanism to preempt OP-TEE mediator.
>
> The same mechanism can be used in the future to preempt mediator
> during translation large (>512 pages) shared buffers.
>
> Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>

Cheers,

--
Julien Grall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel