Re: [PATCH v7 2/9] vmx: spp: Add control flags for Sub-Page Protection(SPP)

[Paolo Bonzini]

On 21/11/19 16:34, Yang Weijiang wrote:
> On Thu, Nov 21, 2019 at 11:04:51AM +0100, Paolo Bonzini wrote:
>> On 19/11/19 09:49, Yang Weijiang wrote:
>>> @@ -228,6 +228,7 @@
>>>  #define X86_FEATURE_FLEXPRIORITY	( 8*32+ 2) /* Intel FlexPriority */
>>>  #define X86_FEATURE_EPT			( 8*32+ 3) /* Intel Extended Page Table */
>>>  #define X86_FEATURE_VPID		( 8*32+ 4) /* Intel Virtual Processor ID */
>>> +#define X86_FEATURE_SPP			( 8*32+ 5) /* Intel EPT-based Sub-Page Write Protection */
>>
>> Please do not include X86_FEATURE_SPP.  In general I don't like the VMX
>> features word, but apart from that SPP is not a feature that affects all
>> VMs in the same way as EPT or FlexPriority.
>>
> So what's a friendly way to let a user check if SPP feature is there?

QEMU for example ships with a program called vmxcap (though it requires
root).  We also could write a program to analyze the KVM capabilities
and print them, and put it in tools/kvm.

Thanks,

Paolo