linux-kernel - Re: [PATCH v5 13/14] iommu/amd: Refactor logic to program the host page table in DTE

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Message-ID: <aRZNw3OFePohDLTI@Asurada-Nvidia>
Date: Thu, 13 Nov 2025 13:29:39 -0800
From: Nicolin Chen <nicolinc@...dia.com>
To: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
CC: <jgg@...dia.com>, <linux-kernel@...r.kernel.org>, <robin.murphy@....com>,
	<will@...nel.org>, <joro@...tes.org>, <kevin.tian@...el.com>,
	<jsnitsel@...hat.com>, <vasant.hegde@....com>, <iommu@...ts.linux.dev>,
	<santosh.shukla@....com>, <sairaj.arunkodilkar@....com>, <jon.grimm@....com>,
	<prashanthpra@...gle.com>, <wvw@...gle.com>, <wnliu@...gle.com>,
	<gptran@...gle.com>, <kpsingh@...gle.com>, <joao.m.martins@...cle.com>,
	<alejandro.j.jimenez@...cle.com>
Subject: Re: [PATCH v5 13/14] iommu/amd: Refactor logic to program the host
 page table in DTE

On Thu, Nov 13, 2025 at 01:19:16PM -0800, Nicolin Chen wrote:
> On Wed, Nov 12, 2025 at 06:25:05PM +0000, Suravee Suthikulpanit wrote:
> >  	else {
> > @@ -2097,35 +2115,29 @@ static void set_dte_entry(struct amd_iommu *iommu,
> >  						       &pt_info);
> >  			}
> >  
> > -			new.data[0] |= __sme_set(pt_info.host_pt_root) |
> > -				       (pt_info.mode & DEV_ENTRY_MODE_MASK)
> > -					       << DEV_ENTRY_MODE_SHIFT;
> > +			pt_info.host_pt_root = __sme_set(pt_info.host_pt_root);
> >  		}
> >  	}
> 
> And this __IOMMU_DOMAIN_PAGING path seems to be used by v1 only.
> So, it could be squashed into amd_iommu_set_dte_v1(). This could
> tidy set_dte_entry() further.

Having looked at PATCH-14, I realized that amd_iommu_set_dte_v1()
is shared with the nesting pathway.

So perhaps:
	else if (domain->domain.type & __IOMMU_DOMAIN_PAGING &&
		 domain->pd_mode == PD_MODE_V1) {
		struct pt_iommu_amdv1_hw_info pt_info;

		....; // <--move here
		amd_iommu_set_dte_v1(dev_data, domain, domid, &pt_info, &new)
	} else

Nicolin