Re: [XEN PATCH v1 4/4] x86:hvm: make nestedhvm support optional

[Denis Mukhin <dmkhn@xxxxxxxxx>]

Hi,

On Thursday, March 20th, 2025 at 3:40 AM, Sergiy Kibrik 
<Sergiy_Kibrik@xxxxxxxx> wrote:

> 
> 
> Introduce NESTEDHVM config option that controls nested virtualization in both
> SVM & VMX code. The option is for reduction of dead code on systems that
> aren't intended to run in nested mode.
> 
> Signed-off-by: Sergiy Kibrik Sergiy_Kibrik@xxxxxxxx
> 
> ---
> xen/arch/x86/Kconfig | 5 +++++
> xen/arch/x86/hvm/Makefile | 2 +-
> xen/arch/x86/hvm/svm/Makefile | 2 +-
> xen/arch/x86/hvm/svm/entry.S | 2 ++
> xen/arch/x86/hvm/svm/svm.c | 4 ++++
> xen/arch/x86/hvm/vmx/Makefile | 2 +-
> xen/arch/x86/hvm/vmx/entry.S | 2 ++
> xen/arch/x86/hvm/vmx/vmcs.c | 8 +++++---
> xen/arch/x86/hvm/vmx/vmx.c | 10 +++++++++-
> xen/arch/x86/include/asm/hvm/nestedhvm.h | 10 +++++++++-
> 10 files changed, 39 insertions(+), 8 deletions(-)
> 
> diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig
> index 6e41bc0fb4..bc140d8b77 100644
> --- a/xen/arch/x86/Kconfig
> +++ b/xen/arch/x86/Kconfig
> @@ -144,6 +144,11 @@ config INTEL_VMX
> If your system includes a processor with Intel VT-x support, say Y.
> If in doubt, say Y.
> 
> +config NESTEDHVM
> + bool "Support nested virtualization" if EXPERT
> + depends on HVM
> + default y

There's dedicated Kconfig for HVM build-time configuration on staging at:

  arch/x86/hvm/Kconfig

Suggest plumbing new knob there.

Thanks,
Denis