linux-kernel - Re: [PATCH 06/25] x86/virt/tdx: Export TDX KeyID information

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Message-ID: <19dcfa1b-08fa-4a0b-9a9d-5df80fa94a41@intel.com>
Date: Fri, 30 Aug 2024 14:18:35 -0700
From: Dave Hansen <dave.hansen@...el.com>
To: "Edgecombe, Rick P" <rick.p.edgecombe@...el.com>,
 "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
 "pbonzini@...hat.com" <pbonzini@...hat.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 06/25] x86/virt/tdx: Export TDX KeyID information

On 8/30/24 12:16, Edgecombe, Rick P wrote:
...>> In other words, should we export the global KeyID, or export a
function
>> to do the flush and then never actually expose the KeyID?
> 
> We could split it into two helpers if we wanted to remove the export of
> tdx_global_keyid. One for global key id and one that only takes TD range key
> ids. Adding more layers is a downside.

I do like the idea of exporting a couple of helpers that are quite hard
to misuse instead of exporting the variable.

> Separate from Dave's question, I wonder if we should open code set_hkid_to_hpa()
> inside tdh_phymem_page_wbinvd(). The signature could change to
> tdh_phymem_page_wbinvd(hpa_t pa, u16 hkid). set_hkid_to_hpa() is very
> lightweight, so I don't think doing it outside the loop is much gain. It makes
> the code cleaner.

Yeah, do what's cleanest.  This is all super cold code.