On Thu, 11 Jun 2020 05:15:21 -0700
Liu Yi L <yi.l.liu@xxxxxxxxx> wrote:
> IOMMUs that support nesting translation needs report the capability info
> to userspace, e.g. the format of first level/stage paging structures.
>
> Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> CC: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Cc: Eric Auger <eric.auger@xxxxxxxxxx>
> Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> Cc: Joerg Roedel <joro@xxxxxxxxxx>
> Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
> ---
> @Jean, Eric: as nesting was introduced for ARM, but looks like no actual
> user of it. right? So I'm wondering if we can reuse DOMAIN_ATTR_NESTING
> to retrieve nesting info? how about your opinions?
>
> include/linux/iommu.h | 1 +
> include/uapi/linux/iommu.h | 34 ++++++++++++++++++++++++++++++++++
> 2 files changed, 35 insertions(+)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 78a26ae..f6e4b49 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -126,6 +126,7 @@ enum iommu_attr {
> DOMAIN_ATTR_FSL_PAMUV1,
> DOMAIN_ATTR_NESTING, /* two stages of translation */
> DOMAIN_ATTR_DMA_USE_FLUSH_QUEUE,
> + DOMAIN_ATTR_NESTING_INFO,
> DOMAIN_ATTR_MAX,
> };
>
> diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
> index 303f148..02eac73 100644
> --- a/include/uapi/linux/iommu.h
> +++ b/include/uapi/linux/iommu.h
> @@ -332,4 +332,38 @@ struct iommu_gpasid_bind_data {
> };
> };
>
> +struct iommu_nesting_info {
> + __u32 size;
> + __u32 format;
> + __u32 features;
> +#define IOMMU_NESTING_FEAT_SYSWIDE_PASID (1 << 0)
> +#define IOMMU_NESTING_FEAT_BIND_PGTBL (1 << 1)
> +#define IOMMU_NESTING_FEAT_CACHE_INVLD (1 << 2)
> + __u32 flags;
> + __u8 data[];
> +};
> +
> +/*
> + * @flags: VT-d specific flags. Currently reserved for future
> + * extension.
> + * @addr_width: The output addr width of first level/stage translation
> + * @pasid_bits: Maximum supported PASID bits, 0 represents no PASID
> + * support.
> + * @cap_reg: Describe basic capabilities as defined in VT-d capability
> + * register.
> + * @cap_mask: Mark valid capability bits in @cap_reg.
> + * @ecap_reg: Describe the extended capabilities as defined in VT-d
> + * extended capability register.
> + * @ecap_mask: Mark the valid capability bits in @ecap_reg.
Please explain this a little further, why do we need to tell userspace
about cap/ecap register bits that aren't valid through this interface?
Thanks,
Alex
> + */
> +struct iommu_nesting_info_vtd {
> + __u32 flags;
> + __u16 addr_width;
> + __u16 pasid_bits;
> + __u64 cap_reg;
> + __u64 cap_mask;
> + __u64 ecap_reg;
> + __u64 ecap_mask;
> +};
> +
> #endif /* _UAPI_IOMMU_H */
