linux-kernel - Re: [PATCH v19 039/130] KVM: TDX: initialize VM with TDX specific parameters

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Message-ID: <54f933223d904871d6e10ef8a6c7c5e9c3ab0122.camel@intel.com>
Date: Thu, 11 Apr 2024 19:51:55 +0000
From: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>
To: "Yamahata, Isaku" <isaku.yamahata@...el.com>
CC: "Zhang, Tina" <tina.zhang@...el.com>, "isaku.yamahata@...ux.intel.com"
	<isaku.yamahata@...ux.intel.com>, "seanjc@...gle.com" <seanjc@...gle.com>,
	"Huang, Kai" <kai.huang@...el.com>, "Chen, Bo2" <chen.bo@...el.com>,
	"sagis@...gle.com" <sagis@...gle.com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "Yuan, Hang" <hang.yuan@...el.com>, "Aktas,
 Erdem" <erdemaktas@...gle.com>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>, "Li, Xiaoyao"
	<xiaoyao.li@...el.com>, "isaku.yamahata@...il.com" <isaku.yamahata@...il.com>
Subject: Re: [PATCH v19 039/130] KVM: TDX: initialize VM with TDX specific
 parameters

On Thu, 2024-04-11 at 12:26 -0700, Isaku Yamahata wrote:
> > 
> > So this enables features based on xss support in the passed CPUID, but these
> > features are not
> > dependent xsave. You could have CET without xsave support. And in fact
> > Kernel IBT doesn't use it. To
> > utilize CPUID leafs to configure features, but diverge from the HW meaning
> > seems like asking for
> > trouble.
> 
> TDX module checks the consistency.  KVM can rely on it not to re-implement it.
> The TDX Base Architecture specification describes what check is done.
> Table 11.4: Extended Features Enumeration and Execution Control

The point is that it is an strange interface. Why not take XFAM as a specific
field in struct kvm_tdx_init_vm?