linux-kernel - Re: [PATCH v4 16/16] iommu/amd: Add support for nested domain attach/detach

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Message-ID: <20251023131725.GG262900@nvidia.com>
Date: Thu, 23 Oct 2025 10:17:25 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Suravee Suthikulpanit <suravee.suthikulpanit@....com>
Cc: nicolinc@...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 v4 16/16] iommu/amd: Add support for nested domain
 attach/detach

On Tue, Oct 21, 2025 at 01:43:24AM +0000, Suravee Suthikulpanit wrote:
> +static int nested_attach_device(struct iommu_domain *dom, struct device *dev)
> +{
> +	struct iommu_dev_data *dev_data = dev_iommu_priv_get(dev);
> +	struct amd_iommu *iommu = get_amd_iommu_from_dev_data(dev_data);
> +	int ret = 0;
> +
> +	if (WARN_ON(dom->type != IOMMU_DOMAIN_NESTED))
> +		return -EINVAL;
> +
> +	mutex_lock(&dev_data->mutex);
> +
> +	/* Update device table entry */
> +	set_dte_nested(iommu, dom, dev_data);
> +	amd_iommu_device_flush_dte(dev_data);
> +	amd_iommu_completion_wait(iommu);

The structure is still upside down and it should probably be fixed
rather than duplicate this code (and missing the clone_aliases!)

dev_update_dte() should take in the struct dev_table_entry *:

static void dev_update_dte(struct iommu_dev_data *dev_data,
			   struct dev_table_entry *dte)
{
	struct amd_iommu *iommu = get_amd_iommu_from_dev(dev_data->dev);

	amd_iommu_update_dte256(iommu, dev_data, dte);
	clone_aliases(iommu, dev_data->dev);
	device_flush_dte(dev_data);
	iommu_completion_wait(iommu);
}

And this function should be exported and called instead of open coding
it above.

Rework set_dte_entry() to return new instead of calling
update_dte256().

Jason