linux-kernel - Re: [PATCH v2 3/4] x86/sev: Fix broken SNP support with KVM module built-in

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Message-ID: <Z50IQyFzuMQRihhF@google.com>
Date: Fri, 31 Jan 2025 10:34:47 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Ashish Kalra <ashish.kalra@....com>
Cc: pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, 
	dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com, 
	thomas.lendacky@....com, john.allen@....com, herbert@...dor.apana.org.au, 
	davem@...emloft.net, joro@...tes.org, suravee.suthikulpanit@....com, 
	will@...nel.org, robin.murphy@....com, michael.roth@....com, 
	dionnaglaze@...gle.com, nikunj@....com, ardb@...nel.org, 
	kevinloughlin@...gle.com, Neeraj.Upadhyay@....com, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org, 
	linux-coco@...ts.linux.dev, iommu@...ts.linux.dev
Subject: Re: [PATCH v2 3/4] x86/sev: Fix broken SNP support with KVM module built-in

On Thu, Jan 30, 2025, Ashish Kalra wrote:
> On 1/30/2025 7:41 PM, Sean Christopherson wrote:
> > On Fri, Jan 31, 2025, Ashish Kalra wrote:
> >> -nosnp:
> >> -	cc_platform_clear(CC_ATTR_HOST_SEV_SNP);
> >> -	return -ENOSYS;
> >>  }
> >>  
> >> -/*
> >> - * This must be called after the IOMMU has been initialized.
> >> - */
> >> -device_initcall(snp_rmptable_init);
> > 
> > There's the wee little problem that snp_rmptable_init() is never called as of
> > this patch.  Dropping the device_initcall() needs to happen in the same patch
> > that wires up the IOMMU code to invoke snp_rmptable_init().
> 
> The issue with that is the IOMMU and x86 maintainers are different, so i
> believe that we will need to split the dropping of device_initcall() in
> platform code and the code to wire up the IOMMU driver to invoke
> snp_rmptable_init(), to get the patch merged in different trees ?

No, that's pure insanity and not how patches that touch multiple subsystems are
handled.  This all goes through one tree, with Acks from the necessary parties.