Messages in this thread | | | Subject | Re: [PATCH 1/7] hyperv: Detect Nested virtualization support for SVM | From | Vineeth Pillai <> | Date | Thu, 8 Apr 2021 09:15:47 -0400 |
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Hi Vitaly,
On 4/8/21 7:06 AM, Vitaly Kuznetsov wrote: > - if (ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) { > + /* > + * AMD does not need enlightened VMCS as VMCB is already a > + * datastructure in memory. > Well, VMCS is also a structure in memory, isn't it? It's just that we > don't have a 'clean field' concept for it and we can't use normal memory > accesses.
Yes, you are right. I was referring to the fact that we cant use normal memory accesses, but is a bit mis-worded.
> >> We need to get the nested >> + * features if SVM is enabled. >> + */ >> + if (boot_cpu_has(X86_FEATURE_SVM) || >> + ms_hyperv.hints & HV_X64_ENLIGHTENED_VMCS_RECOMMENDED) { > Do I understand correctly that we can just look at CPUID.0x40000000.EAX > and in case it is >= 0x4000000A we can read HYPERV_CPUID_NESTED_FEATURES > leaf? I'd suggest we do that intead then. I agree, that is a better way to consolidate both the cases. Will change it in the next iteration. Probably the above code comment is not needed when we consolidate the cases here.
Thanks, Vineeth
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