linux-kernel - Re: [PATCH v3 13/25] KVM: TDX: Fold tdx_mem_page_record_premap

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Message-ID: <aPuqYz3ly5a3__mf@google.com>
Date: Fri, 24 Oct 2025 09:33:39 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Binbin Wu <binbin.wu@...ux.intel.com>
Cc: Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, 
	Tianrui Zhao <zhaotianrui@...ngson.cn>, Bibo Mao <maobibo@...ngson.cn>, 
	Huacai Chen <chenhuacai@...nel.org>, Madhavan Srinivasan <maddy@...ux.ibm.com>, 
	Anup Patel <anup@...infault.org>, Paul Walmsley <pjw@...nel.org>, 
	Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
	Christian Borntraeger <borntraeger@...ux.ibm.com>, Janosch Frank <frankja@...ux.ibm.com>, 
	Claudio Imbrenda <imbrenda@...ux.ibm.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	"Kirill A. Shutemov" <kas@...nel.org>, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, kvm@...r.kernel.org, loongarch@...ts.linux.dev, 
	linux-mips@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, 
	kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org, 
	x86@...nel.org, linux-coco@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	Ira Weiny <ira.weiny@...el.com>, Kai Huang <kai.huang@...el.com>, 
	Michael Roth <michael.roth@....com>, Yan Zhao <yan.y.zhao@...el.com>, 
	Vishal Annapurve <vannapurve@...gle.com>, Rick Edgecombe <rick.p.edgecombe@...el.com>, 
	Ackerley Tng <ackerleytng@...gle.com>
Subject: Re: [PATCH v3 13/25] KVM: TDX: Fold tdx_mem_page_record_premap_cnt()
 into its sole caller

On Fri, Oct 24, 2025, Binbin Wu wrote:
> 
> 
> On 10/17/2025 8:32 AM, Sean Christopherson wrote:
> > Fold tdx_mem_page_record_premap_cnt() into tdx_sept_set_private_spte() as
> > providing a one-off helper for effectively three lines of code is at best a
> > wash, and splitting the code makes the comment for smp_rmb()  _extremely_
> > confusing as the comment talks about reading kvm->arch.pre_fault_allowed
> > before kvm_tdx->state, but the immediately visible code does the exact
> > opposite.
> > 
> > Opportunistically rewrite the comments to more explicitly explain who is
> > checking what, as well as _why_ the ordering matters.
> > 
> > No functional change intended.
> > 
> > Reviewed-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
> > Signed-off-by: Sean Christopherson <seanjc@...gle.com>
> 
> Reviewed-by: Binbin Wu <binbin.wu@...ux.intel.com>
> 
> One nit below.
> 
> [...]
> > +	/*
> > +	 * If the TD isn't finalized/runnable, then userspace is initializing
> > +	 * the VM image via KVM_TDX_INIT_MEM_REGION.  Increment the number of
> > +	 * pages that need to be mapped and initialized via TDH.MEM.PAGE.ADD.
> > +	 * KVM_TDX_FINALIZE_VM checks the counter to ensure all mapped pages
>                                                                    ^
>                                                 Nit: Is pre-mapped better?

Yeah, updated (and then it gets deleted a few commits later :-) ).