Re: RFC: sgx-epc is not listed in machine type help

[Yang Zhong <yang.zhong@intel.com>]

On Thu, Apr 28, 2022 at 02:56:50PM +0200, Jinpu Wang wrote:
> On Thu, Apr 28, 2022 at 2:32 PM Yang Zhong <yang.zhong@intel.com> wrote:
> >
> > On Thu, Apr 28, 2022 at 02:18:54PM +0200, Jinpu Wang wrote:
> > > On Thu, Apr 28, 2022 at 2:05 PM Yang Zhong <yang.zhong@intel.com> wrote:
> > > >
> > > > On Thu, Apr 28, 2022 at 01:59:33PM +0200, Jinpu Wang wrote:
> > > > > Hi Yang, hi Paolo,
> > > > >
> > > > > We noticed sgx-epc machine type is not listed in the output of
> > > > > "qemu-system-x86_64 -M ?",
> > > snip
> > > > >
> > > > >
> > > > > I think this would cause confusion to users, is there a reason behind this?
> > > > >
> > > >
> > > >   No specific machine type for SGX, and SGX is only supported in Qemu PC and Q35 platform.
> > > Hi Yang,
> > >
> > > Thanks for your quick reply. Sorry for the stupid question.
> > > The information I've got from intel or the help sample from
> > > https://www.qemu.org/docs/master/system/i386/sgx.html, We need to
> > > specify commands something like this to run SGX-EPC guest:
> > > qemu-system-x86-64 -m 2G -nographic -enable-kvm -cpu
> > > host,+sgx-provisionkey  -object
> > > memory-backend-epc,id=mem1,size=512M,prealloc=on -M
> > > sgx-epc.0.memdev=mem1,sgx-epc.0.node=0 /tmp/volume-name.img
> > >
> > > Do you mean internally QEMU is converting -M sgx-epc to PC or Q35, can
> > > I choose which one to use?
> > >
> >
> >   Qemu will replace object with compound key, in that time, Paolo asked me
> >   to use "-M sgx-epc..." to replace "-object sgx-epc..." from Qemu command line.
> >
> >   So the "-M sgx-epc..." will get sgx-epc's parameters from hash key, and
> >   do not covert sgx-epc to PC or Q35.
> >
> >   SGX is only one Intel cpu feature, and no dedicated SGX Qemu machine type for SGX.
> >
> >   Another compound key example:
> >   "-M pc,smp.cpus=4,smp.cores=1,smp.threads=1"
> >
> >   Yang
> ah, ok. thx for the sharing.
> so if I specify "-M pc -M sgx-epc.." it will be the explicit way to
> choose PC machine type with sgx feature.
> and "-M q35 -M sgx-epc.." qemu will use Q35 machine type?

  The below command is okay,
  "-M pc,sgx-epc.." or "-M q35,sgx-epc.."

  Yang

> >
> >
> > > Thanks!
> > > Jinpu