Re: [XEN PATCH v1 15/15] x86/hvm: make AMD-V and Intel VT-x support configurable

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 16/04/2024 7:50 am, Sergiy Kibrik wrote:
> From: Xenia Ragiadakou <burzalodowa@gmail.com>
>
> Provide the user with configuration control over the cpu virtualization support
> in Xen by making SVM and VMX options user selectable.
>
> To preserve the current default behavior, both options depend on HVM and
> default to Y.
>
> To prevent users from unknowingly disabling virtualization support, make the
> controls user selectable only if EXPERT is enabled.
> Also make INTEL_IOMMU/AMD_IOMMU options dependant on VMX/SVM options.

Everything else seems ok, but there's no inherent dependency between
VMX/SVM and IOMMUs.  There are certain features (HAP/IOMMU pagetable
sharing, posted interrupts) which do depend on both, but the vast
majority of functionality is independent.

It would be a legitimate config (although getting less plausible, these
days) to have PV && IOMMU && !HVM.

Furthermore, randconfig will do a better job without such restrictions
in place.

~Andrew