linux-kernel - Re: [PATCH v19 023/130] KVM: TDX: Initialize the TDX module when loading the KVM intel kernel module

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Date: Tue, 23 Apr 2024 23:29:37 +0000
From: "Huang, Kai" <kai.huang@...el.com>
To: "seanjc@...gle.com" <seanjc@...gle.com>
CC: "Zhang, Tina" <tina.zhang@...el.com>, "Yuan, Hang" <hang.yuan@...el.com>,
	"Chen, Bo2" <chen.bo@...el.com>, "sagis@...gle.com" <sagis@...gle.com>,
	"isaku.yamahata@...il.com" <isaku.yamahata@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "Aktas, Erdem"
	<erdemaktas@...gle.com>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>, "Yamahata, Isaku"
	<isaku.yamahata@...el.com>, "isaku.yamahata@...ux.intel.com"
	<isaku.yamahata@...ux.intel.com>
Subject: Re: [PATCH v19 023/130] KVM: TDX: Initialize the TDX module when
 loading the KVM intel kernel module

On Tue, 2024-04-23 at 22:59 +0000, Huang, Kai wrote:
> > Right, but that doesn't say why the #UD occurred.  The macro dresses it up in
> > TDX_SW_ERROR so that KVM only needs a single parser, but at the end of the day
> > KVM is still only going to see that SEAMCALL hit a #UD.
> 
> Right.  But is there any problem here?  I thought the point was we can
> just use the error code to tell what went wrong.

Oh, I guess I was replying too quickly.  From the spec, #UD happens when

	IF not in VMX operation or inSMM or inSEAM or 
			((IA32_EFER.LMA & CS.L) == 0)
 		THEN #UD;

Are you worried about #UD was caused by other cases rather than "not in
VMX operation"?

But it's quite obvious the other 3 cases are not possible, correct?