Re: [PATCH 5/7] qmp: Add the qmp_query_sgx_capabilities()

[Yang Zhong]

On Thu, Sep 09, 2021 at 11:36:58AM +0200, Philippe Mathieu-Daudé wrote:
> On 9/9/21 4:51 AM, Yang Zhong wrote:
> > On Wed, Sep 08, 2021 at 10:38:59AM +0200, Philippe Mathieu-Daudé wrote:
> >> On 9/8/21 10:19 AM, Yang Zhong wrote:
> >>> Libvirt can use qmp_query_sgx_capabilities() to get the host
> >>> sgx capabilities.
> >>>
> >>> Signed-off-by: Yang Zhong <yang.zhong@intel.com>
> >>> ---
> >>>  hw/i386/sgx.c              | 66 ++++++++++++++++++++++++++++++++++++++
> >>>  include/hw/i386/sgx.h      |  1 +
> >>>  qapi/misc-target.json      | 18 +++++++++++
> >>>  target/i386/monitor.c      |  5 +++
> >>>  tests/qtest/qmp-cmd-test.c |  1 +
> >>>  5 files changed, 91 insertions(+)
> >>
> >>> +SGXInfo *sgx_get_capabilities(Error **errp)
> >>> +{
> >>> +    SGXInfo *info = NULL;
> >>> +    uint32_t eax, ebx, ecx, edx;
> >>> +
> >>> +    int fd = qemu_open_old("/dev/sgx_vepc", O_RDWR);
> >>> +    if (fd < 0) {
> >>> +        error_setg(errp, "SGX is not enabled in KVM");
> >>> +        return NULL;
> >>> +    }
> >>
> >> Is this Linux specific?
> > 
> >   Philippe, The /dev/sgx_vepc node is used for KVM side to expose the SGX
> >   EPC section to guest. Libvirt then use the '-machine none' qemu command 
> >   to query host SGX capabilities(especially for host SGX EPC section size)
> >   to decide how many SGX VMs will be started in server. If this node doesn't
> >   exist, the reason is host can't support SGX or SGX KVM module is not 
> > compiled
> >   in the kernel. thanks!
> 
> Sorry but you didn't answer my question in an obvious way... Yes or no?

  Yes, this is Linux specific. thanks!
  
  Yang