linux-kernel - Re: [RFC PATCH 09/12] KVM: TDX: Fold tdx_mem_page_record_premap

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Message-ID: <aLDNzk-QaAlfff0C@google.com>
Date: Thu, 28 Aug 2025 14:44:46 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Rick P Edgecombe <rick.p.edgecombe@...el.com>
Cc: Yan Y Zhao <yan.y.zhao@...el.com>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>, 
	"pbonzini@...hat.com" <pbonzini@...hat.com>, Vishal Annapurve <vannapurve@...gle.com>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"michael.roth@....com" <michael.roth@....com>, Ira Weiny <ira.weiny@...el.com>
Subject: Re: [RFC PATCH 09/12] KVM: TDX: Fold tdx_mem_page_record_premap_cnt()
 into its sole caller

On Thu, Aug 28, 2025, Rick P Edgecombe wrote:
> It's unfortunate we didn't have the gmem mmap() support then. Otherwise we could
> have just encrypted it in place.

Yeah, hindsight is definitely 20/20 on that front.  Though I suspect that we'd
never have landed anything if we tried to go straight to support mmap().

> Otherwise, I'm really glad to see these cleanups/scrutiny. I kind of got the
> impression that you wanted to see less TDX churn for a bit.

Heh, believe me, I'm not exactly ecstatic to dive into this.  But, I don't want
to just ignore it, because some of these quirks/warts are already getting in the
way of new development, and if I/we delay such clean ups, the pain is only going
to get worse (and the total cost will be much higher).

Fatigue is a bit of a problem for me, but the biggest issue really is just lack
of cycles (the quick feedback and testing y'all are providing helps tremendously
on that front).  And lack of cycles should be mitigated to some extent as I
(re)familiarize myself with the code; I recognized most of the concepts, but
there are definitely a few places where I'm completely lost, and that makes
reviewing things like dynamic PAMT and hugepage support excrutiatingly slow.

> The fact is, the TDX base support still needs more work like this.

IMO, the most important things to address are cases where the design choices we
made turned out to be suboptimal, i.e. where the behavior itself is problematic.
Code cleanups are definitely welcome too, but my priority is polishing the core
design.