Re: [PATCH v4 10/19] x86/virt: KVM: Move VMXOFF helpers into KVM VMX

[Huang, Kai]

On Fri, 2023-07-28 at 17:08 +0800, Xu, Yilun wrote:
> On 2023-07-21 at 13:18:50 -0700, Sean Christopherson wrote:
> > Now that VMX is disabled in emergencies via the virt callbacks, move the
> > VMXOFF helpers into KVM, the only remaining user.
> 
> Not sure if it's too early to mention.
> 
> Intel TDX Connect could be a future user, it is the TDX extension for
> device security. 
> 
> TDX uses SEAMCALL to interact with TDX Module, and SEAMCALL execution
> requires VMXON. This is also true for TDX Connect. But TDX Connect
> covers more controls out of KVM scope, like PCI IDE, SPDM, IOMMU.
> IOW, other driver modules may use SEAMCALLs and in turn use VMXON/OFF
> for TDX Connect.
> 
> I'm wondering if then we should again move VMXON/OFF helpers back to
> virtext.h
> 
> Or, could we just keep vmxoff unchanged now?
> 

I'd say we should just proceed with Sean's this patch.  Moving VMXON/VMXOFF out
from KVM needs additional things besides keeping the basic vmxon()/vmxoff()
functions at core-x86 in order to handle multiple callers from multiple kernel
components.  And vmxon()/vmxoff() aren't necessary to be in virtext.h either,
depending on the implementation.  Let's handle that when we need that in the
future.