linux-kernel - Re: [PATCH v18 032/121] KVM: x86/mmu: introduce config for PRIVATE KVM MMU

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Date: Mon, 12 Feb 2024 15:18:14 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: isaku.yamahata@...el.com
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	isaku.yamahata@...il.com, erdemaktas@...gle.com, 
	Sean Christopherson <seanjc@...gle.com>, Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>, 
	chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com
Subject: Re: [PATCH v18 032/121] KVM: x86/mmu: introduce config for PRIVATE
 KVM MMU

On Tue, Jan 23, 2024 at 12:55 AM <isaku.yamahata@...el.com> wrote:
>
> From: Isaku Yamahata <isaku.yamahata@...el.com>
>
> To keep the case of non TDX intact, introduce a new config option for
> private KVM MMU support.  At the moment, this is synonym for
> CONFIG_INTEL_TDX_HOST && CONFIG_KVM_INTEL.  The config makes it clear
> that the config is only for x86 KVM MMU.

Better, just put this as:

config KVM_MMU_PRIVATE
    bool

but also add a reverse dependency to KVM_INTEL:

config KVM_INTEL
     tristate "KVM for Intel (and compatible) processors support"
     depends on KVM && IA32_FEAT_CTL
     select KVM_MMU_PRIVATE if INTEL_TDX_HOST
     ...

This matches the usage of kvm-intel-$(INTEL_TDX_HOST) in the Makefile.

Paolo

> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
>  arch/x86/kvm/Kconfig | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
> index cd3de7b9a665..fa00abb9ab39 100644
> --- a/arch/x86/kvm/Kconfig
> +++ b/arch/x86/kvm/Kconfig
> @@ -189,4 +189,8 @@ config KVM_MAX_NR_VCPUS
>           the memory footprint of each KVM guest, regardless of how many vCPUs are
>           created for a given VM.
>
> +config KVM_MMU_PRIVATE
> +       def_bool y
> +       depends on INTEL_TDX_HOST && KVM_INTEL
> +
>  endif # VIRTUALIZATION
> --
> 2.25.1
>