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Volodymyr Babchuk authored
Normal World can share a buffer with OP-TEE for two reasons: 1. A client application wants to exchange data with TA 2. OP-TEE asks for shared buffer for internal needs The second case was handled more strictly than necessary: 1. In RPC request OP-TEE asks for buffer 2. NW allocates buffer and provides it via RPC response 3. Xen pins pages and translates data 4. Xen provides buffer to OP-TEE 5. OP-TEE uses it 6. OP-TEE sends request to free the buffer 7. NW frees the buffer and sends the RPC response 8. Xen unpins pages and forgets about the buffer The problem is that Xen should forget about buffer in between stages 6 and 7. I.e. the right flow should be like this: 6. OP-TEE sends request to free the buffer 7. Xen unpins pages and forgets about the buffer 8. NW frees the buffer and sends the RPC response This is because OP-TEE internally frees the buffer before sending the "free SHM buffer" request. So we have no reason to hold reference for this buffer anymore. Moreover, in multiprocessor systems NW have time to reuse the buffer cookie for another buffer. Xen complained about this and denied the new buffer registration. I have seen this issue while running tests on iMX SoC. So, this patch basically corrects that behavior by freeing the buffer earlier, when handling RPC return from OP-TEE. Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Signed-off-by: Stefano Stabellini <stefano.stabellini@xilinx.com> Release-acked-by: Paul Durrant <paul@xen.org>
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