linux-kernel - Re: [PATCH v1 03/26] iommu/amd: Don't rely on external callers to enable IOMMU SNP support

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Date: Thu, 4 Jan 2024 11:58:29 +0100
From: Joerg Roedel <jroedel@...e.de>
To: Michael Roth <michael.roth@....com>
Cc: x86@...nel.org, kvm@...r.kernel.org, linux-coco@...ts.linux.dev,
	linux-mm@...ck.org, linux-crypto@...r.kernel.org,
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	thomas.lendacky@....com, hpa@...or.com, ardb@...nel.org,
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	jmattson@...gle.com, luto@...nel.org, dave.hansen@...ux.intel.com,
	slp@...hat.com, pgonda@...gle.com, peterz@...radead.org,
	srinivas.pandruvada@...ux.intel.com, rientjes@...gle.com,
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	ak@...ux.intel.com, tony.luck@...el.com,
	sathyanarayanan.kuppuswamy@...ux.intel.com, alpergun@...gle.com,
	jarkko@...nel.org, ashish.kalra@....com, nikunj.dadhania@....com,
	pankaj.gupta@....com, liam.merwick@...cle.com, zhi.a.wang@...el.com
Subject: Re: [PATCH v1 03/26] iommu/amd: Don't rely on external callers to
 enable IOMMU SNP support

On Sat, Dec 30, 2023 at 10:19:31AM -0600, Michael Roth wrote:
> From: Ashish Kalra <ashish.kalra@....com>
> 
> Currently the expectation is that the kernel will call
> amd_iommu_snp_enable() to perform various checks and set the
> amd_iommu_snp_en flag that the IOMMU uses to adjust its setup routines
> to account for additional requirements on hosts where SNP is enabled.
> 
> This is somewhat fragile as it relies on this call being done prior to
> IOMMU setup. It is more robust to just do this automatically as part of
> IOMMU initialization, so rework the code accordingly.
> 
> There is still a need to export information about whether or not the
> IOMMU is configured in a manner compatible with SNP, so relocate the
> existing amd_iommu_snp_en flag so it can be used to convey that
> information in place of the return code that was previously provided by
> calls to amd_iommu_snp_enable().
> 
> While here, also adjust the kernel messages related to IOMMU SNP
> enablement for consistency/grammar/clarity.
> 
> Suggested-by: Borislav Petkov (AMD) <bp@...en8.de>
> Signed-off-by: Ashish Kalra <ashish.kalra@....com>
> Co-developed-by: Michael Roth <michael.roth@....com>
> Signed-off-by: Michael Roth <michael.roth@....com>

Acked-by: Joerg Roedel <jroedel@...e.de>

-- 
Jörg Rödel
jroedel@...e.de

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