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

[Philippe Mathieu-Daudé]

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?