Re: [PATCH v14 08/15] qemu: Get SGX capabilities form QMP
On 8/22/22 06:34, Yang, Lin A wrote:
@Michal, do you have any updated for v14 patches? If yes, I can rework on
top of your changes and submit for review.
https://gitlab.com/MichalPrivoznik/libvirt/-/commits/sgx_rework
<https://gitlab.com/MichalPrivoznik/libvirt/-/commits/sgx_rework> ?
It's sgx_rework_v2 but it hasn't worked all Peter's suggestion in, yet.
Anyway, I've experimented with plain QEMU a bit (I think Peter asked
this somewhere in the review) and the way SGX works is by using a memory
that QEMU already has, e.g.:
./qemu-system-x86_64 \
-S \
-machine
pc-q35-6.2,usb=off,dump-guest-core=off,sgx-epc.0.memdev=memepc0,sgx-epc.0.node=0,sgx-epc.1.memdev=memepc1,sgx-epc.1.node=0
\
-accel tcg \
-cpu qemu64 \
-m 128 \
-device virtio-balloon-pci,id=balloon0 \
-object
'{"qom-type":"memory-backend-epc","id":"memepc0","prealloc":true,"size":67108864}'
\
-object
'{"qom-type":"memory-backend-epc","id":"memepc1","prealloc":true,"size":167}'
\
-qmp stdio
{"QMP": {"version": {"qemu": {"micro": 93,
"minor": 0, "major": 7}, "package":
"v7.1.0-rc3-30-g08eb7aa318"}, "capabilities": ["oob"]}}
{"execute":"qmp_capabilities"}
{"return": {}}
{"execute":"query-memory-size-summary"}
{"return": {"base-memory": 134217728, "plugged-memory": 0}}
{"execute":"query-balloon"}
{"return": {"actual": 134217728}}
{"execute":"query-memory-devices"}
{"return": [{"type": "sgx-epc", "data":
{"memdev": "/objects/memepc0", "memaddr": 4294967296,
"size": 67108864, "node": 0}}, {"type": "sgx-epc",
"data": {"memdev": "/objects/memepc1", "memaddr":
4362076160, "size": 167, "node": 0}}]}
{"execute":"query-memdev"}
{"return": [{"share": true, "reserve": true,
"prealloc": true, "host-nodes": [], "size": 167,
"merge": false, "dump": false, "policy":
"default", "id": "memepc1"}, {"share": false,
"reserve": true, "prealloc": false, "host-nodes": [],
"size": 134217728, "merge": true, "dump": false,
"policy": "default", "id": "pc.ram"},
{"share": true, "reserve": true, "prealloc": true,
"host-nodes": [], "size": 67108864, "merge": false,
"dump": false, "policy": "default", "id":
"memepc0"}]}
IOW, it looks like memory-backend-epc does not add any additional memory (like other
backends do). Therefore I'm not sure whether <memory/> device is the right
element to represent this, but I don't have a good alternative either.
Feel free to take my patches and rework them as I'll be traveling in near future and
might not get enough time to work on this.
Michal