Messages in this thread | | | Date | Thu, 5 Nov 2020 11:25:22 +0800 | From | Shuo A Liu <> | Subject | Re: [PATCH v5 03/17] x86/acrn: Introduce an API to check if a VM is privileged |
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On Wed 4.Nov'20 at 19:51:57 +0100, Borislav Petkov wrote: >On Wed, Nov 04, 2020 at 11:50:27AM +0800, Shuo A Liu wrote: >> On Tue 3.Nov'20 at 11:25:38 +0100, Borislav Petkov wrote: >> > On Tue, Nov 03, 2020 at 02:27:18PM +0800, Shuo A Liu wrote: >> > > The code just followed KVM style (see kvm_arch_para_features()). >> > >> > Do you see Documentation/virt/kvm/cpuid.rst? >> >> OK. It documents the leaf number. > >It also says > >"Note also that old hosts set eax value to 0x0. This should be >interpreted as if the value was 0x40000001."
Ok.
> >Does this hold true for the acrn HV? The fact that I'm asking about >all those things should give you a hint that documenting the API is >important.
No, acrn HV is always return eax with maximum leaf number.
Let me add the document.
> >> > Now where is yours explaining what your hypervisor is doing? >> >> Currently, it is in arch/x86/include/asm/acrn.h. > >Yeah, you can't expect people to go scrape it from headers though - it >should be concentrated in a doc file. > >> If the leaf numbers be documented explicitly (like kvm), i think i can >> use them as eax of cpuid_eax() directly (back to your first comment). > >Which means, you don't need to do the logical OR-ing which kvm does >because of what I pasted above about eax being 0 on old hosts. Now we're >getting somewhere...
Yes.
> >> cpuid_eax(ACRN_CPUID_FEATURES)... >> >> If you looking at implementation of acrn-hypervisor, you will found the >> leaf number is hardcoded in the hypervisor. So, they also can be >> documented explicitly. > >Ok. > >> OK. I can add a similar cpuid.rst for acrn. > >Yes please. > >> Yes. Fix patches are always welcome. > >Ok, good, the thing is open. You could put that in the doc too, along >with the link so that people can find it.
OK.
Thanks shuo
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