Re: [PATCH v3 00/16] KVM: x86/tdx: Have TDX handle VMXON during bringup

[dan.j.williams]

Sean Christopherson wrote:
> Assuming I didn't break anything between v2 and v3, I think this is ready to
> rip.  Given the scope of the KVM changes, and that they extend outside of x86,
> my preference is to take this through the KVM tree.  But a stable topic branch
> in tip would work too, though I think we'd want it sooner than later so that
> it can be used as a base. 
> 
> Chao, I deliberately omitted your Tested-by, as I shuffled things around enough
> while splitting up the main patch that I'm not 100% positive I didn't regress
> anything relative to v2.
> 
> 
> The idea here is to extract _only_ VMXON+VMXOFF and EFER.SVME toggling.  AFAIK
> there's no second user of SVM, i.e. no equivalent to TDX, but I wanted to keep
> things as symmetrical as possible.
> 
> TDX isn't a hypervisor, and isn't trying to be a hypervisor. Specifically, TDX
> should _never_ have it's own VMCSes (that are visible to the host; the
> TDX-Module has it's own VMCSes to do SEAMCALL/SEAMRET), and so there is simply
> no reason to move that functionality out of KVM.
> 
> With that out of the way, dealing with VMXON/VMXOFF and EFER.SVME is a fairly
> simple refcounting game.
> 
> v3:
>  - https://lore.kernel.org/all/20251206011054.494190-1-seanjc@xxxxxxxxxx
>  - Split up the move from KVM => virt into smaller patches. [Dan]
>  - Collect reviews. [Dan, Chao, Dave]
>  - Update sample dmesg output and hotplug angle in docs. [Chao]
>  - Add comments in kvm_arch_shutdown() to try and explain the madness. [Dave]
>  - Add a largely superfluous smp_wmb() in kvm_arch_shutdown() to provide a
>    convienent location for documenting the flow. [Dave]
>  - Disable preemption in x86_virt_{get,put}_ref() so that changes in how
>    KVM and/or TDX use the APIs doesn't result in bugs. [Xu]
>  - Add a patch to drop the bogus "IRQs must be disabled" rule in
>    tdx_cpu_enable().
>  - Tag more TDX helpers as __init. [Chao]
>  - Don't treat loading kvm-intel.ko with tdx=1 as fatal if the system doesn't
>    have a TDX-Module available. [Chao]

I went through the rest of the patches, the finer grained splits make
sense. No significant concerns, so for the series:

Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>

...I expect Chao or Yilun to have a chance to offer a Tested-by per your
comment above.