linux-kernel - Re: [PATCH v19 007/130] x86/virt/tdx: Export SEAMCALL functions

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Message-ID: <e6e8f585-b718-4f53-88f6-89832a1e4b9f@intel.com>
Date: Fri, 15 Mar 2024 13:02:01 +1300
From: "Huang, Kai" <kai.huang@...el.com>
To: <isaku.yamahata@...el.com>, <kvm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: <isaku.yamahata@...il.com>, Paolo Bonzini <pbonzini@...hat.com>,
	<erdemaktas@...gle.com>, Sean Christopherson <seanjc@...gle.com>, Sagi Shahar
	<sagis@...gle.com>, <chen.bo@...el.com>, <hang.yuan@...el.com>,
	<tina.zhang@...el.com>
Subject: Re: [PATCH v19 007/130] x86/virt/tdx: Export SEAMCALL functions

On 26/02/2024 9:25 pm, isaku.yamahata@...el.com wrote:
> From: Kai Huang <kai.huang@...el.com>
> 
> KVM will need to make SEAMCALLs to create and run TDX guests.  Export
> SEAMCALL functions for KVM to use.
> 

Could you also list the reason that we want to expose __seamcall() 
directly, rather than wanting to put some higher level wrappers in the 
TDX host code, and export them?

For example, we can give a summary of the SEAMCALLs (e.g., how many in 
total, and roughly introduce them based on categories) that will be used 
by KVM, and clarify the reasons why we want to just export __seamcall().

E.g., we can say something like this:

TD;LR:

KVM roughly will need to use dozens of SEAMCALLs, and all these are 
logically related to creating and running TDX guests.  It makes more 
sense to just export __seamcall() and let KVM maintain these VM-related 
wrappers rather than having the TDX host code to provide wrappers for 
each SEAMCALL or higher-level abstraction.

Long version:

You give a detailed explanation of SEAMCALLs that will be used by KVM, 
and clarify logically it's better to manage these code in KVM.