linux-kernel - Re: [PATCH v2 3/7] KVM: x86/tdx: Do VMXON and TDX-Module initialization during subsys init

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Message-ID: <aTdchSmOBo60vbZT@google.com>
Date: Mon, 8 Dec 2025 15:17:25 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: dan.j.williams@...el.com
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	Kiryl Shutsemau <kas@...nel.org>, Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org, 
	linux-coco@...ts.linux.dev, kvm@...r.kernel.org, 
	Chao Gao <chao.gao@...el.com>
Subject: Re: [PATCH v2 3/7] KVM: x86/tdx: Do VMXON and TDX-Module
 initialization during subsys init

On Sat, Dec 06, 2025, dan.j.williams@...el.com wrote:
> Sean Christopherson wrote:
> Given this routine now has nothing to do...
> 
> > +	 * TDX-specific cpuhp callback to disallow offlining the last CPU in a
> > +	 * packing while KVM is running one or more TDs.  Reclaiming HKIDs
> > +	 * requires doing PAGE.WBINVD on every package, i.e. offlining all CPUs
> > +	 * of a package would prevent reclaiming the HKID.
> >  	 */
> > +	r = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "kvm/cpu/tdx:online",
> > +			      tdx_online_cpu, tdx_offline_cpu);
> 
> ...the @startup param can be NULL. That also saves some grep pain no
> more multiple implementations of a "tdx_online_cpu".
> 
> Along those lines, should tdx_offline_cpu() become
> kvm_tdx_offline_cpu()?
> 
> [..]
> >  /*
> >   * Add a memory region as a TDX memory block.  The caller must make sure
> > @@ -1156,67 +1194,50 @@ static int init_tdx_module(void)
> >  	goto out_put_tdxmem;
> >  }
> >  
> > -static int __tdx_enable(void)
> > +static int tdx_enable(void)
> 
> Almost commented about this being able to be __init now, but then I see
> you have a combo patch for that later.
> 
> With or without the additional tdx_{on,off}line_cpu fixups:

I think the fixups you're looking for are in patch 5, "/virt/tdx: KVM: Consolidate
TDX CPU hotplug handling", or did I misunderstand?