linux-kernel - Re: [PATCH v6 5/9] iommu/amd: Modify set_dte

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Message-ID: <20241016140728.GN3559746@nvidia.com>
Date: Wed, 16 Oct 2024 11:07:28 -0300
From: Jason Gunthorpe <jgg@...dia.com>
To: Suravee Suthikulpanit <suravee.suthikulpanit@....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 5/9] iommu/amd: Modify set_dte_entry() to use 256-bit
 DTE helpers

On Wed, Oct 16, 2024 at 05:17:52AM +0000, Suravee Suthikulpanit wrote:
> +	if (dev_data->ats_enabled)
> +		new.data[1] |= DTE_FLAG_IOTLB;
> +	else
> +		new.data[1] &= ~DTE_FLAG_IOTLB;

No need to clear, it is already 0

> -		tmp = DTE_GCR3_VAL_C(gcr3) << DTE_GCR3_SHIFT_C;
> -		flags    |= tmp;
> +	old_domid = READ_ONCE(dte->data[1]) & DEV_DOMID_MASK;
> +	new.data[1] &= ~DEV_DOMID_MASK;
> +	new.data[1] |= domid;

Also no need to clear, it is already zero.

Jason