Messages in this thread | | | Subject | Re: [PATCH v8 02/11] x86/tdx: Introduce INTEL_TDX_GUEST config option | From | Dave Hansen <> | Date | Tue, 5 Oct 2021 07:09:59 -0700 |
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On 10/5/21 6:29 AM, Sathyanarayanan Kuppuswamy Natarajan wrote: > On Mon, Oct 4, 2021 at 9:53 PM Randy Dunlap <rdunlap@infradead.org> wrote: >> On 10/4/21 7:51 PM, Kuppuswamy Sathyanarayanan wrote: >>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >>> index 2b2a9639d8ae..c42dd8a2d1f4 100644 >>> --- a/arch/x86/Kconfig >>> +++ b/arch/x86/Kconfig >>> @@ -865,6 +865,20 @@ config ACRN_GUEST >>> IOT with small footprint and real-time features. More details can be >>> found inhttps://projectacrn.org/. >>> >>> +config INTEL_TDX_GUEST >>> + bool "Intel Trusted Domain eXtensions Guest Support" >>> + depends on X86_64 && CPU_SUP_INTEL && PARAVIRT >>> + depends on SECURITY >>> + select X86_X2APIC >> Apparently some Intel CPUs don't have the x2apic feature, since the >> Kconfig help text for X86_X2APIC says: >> >> This enables x2apic support on CPUs that have this feature. >> >> so how is it safe to set/enable/select that kconfig symbol? >> >> Will the x2apic code just safely not work if the h/w feature is >> missing? > For the TDX guest, x2apic will be emulated. So it will exist in our > case. Even if x2apic or TDX guest is not supported by CPU, it will > boot just fine.
This doesn't really explain the "select X86_X2APIC", though.
You just said that TDX doesn't *require* X2APIC. So, why is it being selected? What is the specific connection between TDX and X2APIC?
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