linux-kernel - Re: [PATCH V9 02/10] iommu/uapi: Define a mask for bind data

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Message-ID: <c51ba1a1-343d-c458-1529-5f9fb11d13b9@redhat.com>
Date:   Wed, 12 Feb 2020 13:43:43 +0100
From:   Auger Eric <eric.auger@...hat.com>
To:     Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux-foundation.org,
        LKML <linux-kernel@...r.kernel.org>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>,
        David Woodhouse <dwmw2@...radead.org>
Cc:     Yi Liu <yi.l.liu@...el.com>, "Tian, Kevin" <kevin.tian@...el.com>,
        Raj Ashok <ashok.raj@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>,
        Jonathan Cameron <jic23@...nel.org>
Subject: Re: [PATCH V9 02/10] iommu/uapi: Define a mask for bind data

Hi Jacob,

On 1/29/20 7:01 AM, Jacob Pan wrote:
> Memory type related guest PASID bind data can be grouped together for
> one simple check.
Those are flags related to memory type.
> Link: https://lore.kernel.org/linux-iommu/20200109095123.17ed5e6b@jacob-builder/
not sure the link is really helpful.
> 
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> ---
>  include/uapi/linux/iommu.h | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index 4ad3496e5c43..fcafb6401430 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -284,7 +284,10 @@ struct iommu_gpasid_bind_data_vtd {
>  	__u32 pat;
>  	__u32 emt;
>  };
> -
> +#define IOMMU_SVA_VTD_GPASID_EMT_MASK	(IOMMU_SVA_VTD_GPASID_CD | \
> +					 IOMMU_SVA_VTD_GPASID_EMTE | \
> +					 IOMMU_SVA_VTD_GPASID_PCD |  \
> +					 IOMMU_SVA_VTD_GPASID_PWT)
Why EMT rather than MT or MTS?
the spec says:
Those fields are treated as Reserved(0) for implementations not
supporting Memory Type (MTS=0 in Extended Capability Register).

>  /**
>   * struct iommu_gpasid_bind_data - Information about device and guest PASID binding
>   * @version:	Version of this data structure
> 

Thanks

Eric