linux-kernel - Re: [PATCH 21/25] KVM: x86: Introduce KVM_TDX_GET

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Message-ID: <61e8b41970f0feddef3d6c3114d40ae8e4992784.camel@intel.com>
Date: Tue, 27 Aug 2024 20:40:58 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "kvm@...r.kernel.org" <kvm@...r.kernel.org>, "pbonzini@...hat.com"
	<pbonzini@...hat.com>, "nik.borisov@...e.com" <nik.borisov@...e.com>,
	"seanjc@...gle.com" <seanjc@...gle.com>
CC: "Li, Xiaoyao" <xiaoyao.li@...el.com>, "tony.lindgren@...ux.intel.com"
	<tony.lindgren@...ux.intel.com>, "Huang, Kai" <kai.huang@...el.com>,
	"isaku.yamahata@...il.com" <isaku.yamahata@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 21/25] KVM: x86: Introduce KVM_TDX_GET_CPUID

On Tue, 2024-08-27 at 15:19 +0300, Nikolay Borisov wrote:

> > 
> > But beyond checking for supported features, there are also bug fixes that
> > can
> > affect usability. In the NO_RBP_MOD case we need a specific recent TDX
> > module in
> > order to remove the RBP workaround patches.
> 
> My point was that if having the NO_RPB_MOD implied that the CPUID 
> 0x8000000 configuration capability is also there (not that there is a 
> direct connection between the too but it seems the TDX module isn't 
> being updated that often, I might be wrong of course!), there is no 
> point in having the workaround as NO_RPB_MOD is the minimum required 
> version.

Having NO_RBP_MOD won't imply 0x80000008 configuration capability. We will have
to check for a new feature bit for that. We should wait until it's finalized to
add the code.