linux-kernel - Re: [PATCH v6 0/9] iommu/amd: Use 128-bit cmpxchg operation to update DTE

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Message-ID: <e617c4ae-c5fb-444a-9649-ffc7d41f79ba@amd.com>
Date: Thu, 31 Oct 2024 16:15:02 +0700
From: "Suthikulpanit, Suravee" <suravee.suthikulpanit@....com>
To: Jason Gunthorpe <jgg@...dia.com>
Cc: linux-kernel@...r.kernel.org, iommu@...ts.linux.dev, joro@...tes.org,
 robin.murphy@....com, vasant.hegde@....com, kevin.tian@...el.com,
 jon.grimm@....com, santosh.shukla@....com, pandoh@...gle.com,
 kumaranand@...gle.com
Subject: Re: [PATCH v6 0/9] iommu/amd: Use 128-bit cmpxchg operation to update
 DTE

On 10/16/2024 9:22 PM, Jason Gunthorpe wrote:
>
> ....
>
> I wanted to see how far this was to being split up neatly like ARM is,
> I came up with this, which seems pretty good to me. This would
> probably be the next step to get to, then you'd lift the individual
> set functions higher up the call chain into their respective attach
> functions.

I like this idea and will look into adopting this code when I submit the 
nested translation stuff (right after this series) since it will affect 
the set_dte_entry().

> .....
> 
> static void set_dte_entry(struct amd_iommu *iommu,
> 			  struct iommu_dev_data *dev_data)
> {
> 	u32 old_domid;
> 	struct dev_table_entry new = {};
> 	struct protection_domain *domain = dev_data->domain;
> 	struct gcr3_tbl_info *gcr3_info = &dev_data->gcr3_info;
> 	struct dev_table_entry *dte = &get_dev_table(iommu)[dev_data->devid];
> 
> 	make_clear_dte(dev_data, dte, &new);
> 	if (gcr3_info && gcr3_info->gcr3_tbl)
> 		set_dte_gcr3_table(iommu, dev_data, &new);
> 	else if (domain->iop.mode == PAGE_MODE_NONE)
> 		set_dte_identity(iommu, dev_data, &new);
> 	else
> 		set_dte_paging(iommu, dev_data, &new);

This will need to be change once we add nested translation support 
because we need to call both set_dte_paging() and set_dte_gcr3().

Thanks,
Suravee