Re: [libvirt][PATCH v16 5/9] conf: Introduce SGX EPC element into device memory xml

On Fri, Oct 14, 2022 at 01:12:28PM +0200, Michal Prívozník wrote: > On 10/8/22 06:00, Lin Yang wrote:

> > # ./qemu-system-x86_64 -S -nographic -nodefaults -m 128 \ > -machine pc,sgx-epc.0.memdev=memepc0,sgx-epc.0.node=0 \ > -object '{"qom-type":"memory-backend-epc","id":"memepc0","prealloc":true,"size":67108864,"host-nodes":[0],"policy":"bind"}' \ > -monitor stdio > QEMU 7.1.50 monitor - type 'help' for more information > (qemu) info memory-devices > Memory device [sgx-epc]: "" > memaddr: 0x100000000 > size: 67108864 > node: 0 > memdev: /objects/memepc0 > (qemu) info memory_size_summary > base memory: 134217728 > plugged memory: 0 > (qemu) I'm not sure this check is showing us the truth. In backends/hostmem-epc.c, sgx_epc_backend_memory_alloc is opening /dev/sgx_vepc and mmap()ing the requested size from that file. IOW that's clearly in addition to whatever has been mapped as the main RAM. In hw/i386/sgx-epc.c, sgx_epc_md_get_plugged_size is hardcoded to always return 0, which is why 'plugged memory' is reported as zero above. I don't know what it is reporting zero. Is this because the SGX RAM is not accessible to the guest OS as "normal" RAM perhaps, and thus to be reported differently.