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 <[email protected]>
Acked-by: Julien Grall <[email protected]>
Cheers,
--
Julien Grall
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