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.t...@intel.com>
CC: Jacob Pan <jacob.jun....@linux.intel.com>
Cc: Alex Williamson <alex.william...@redhat.com>
Cc: Eric Auger <eric.au...@redhat.com>
Cc: Jean-Philippe Brucker <jean-phili...@linaro.org>
Cc: Joerg Roedel <j...@8bytes.org>
Cc: Lu Baolu <baolu...@linux.intel.com>
Signed-off-by: Liu Yi L <yi.l....@intel.com>
Signed-off-by: Jacob Pan <jacob.jun....@linux.intel.com>
---
@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.
+ */
+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 */
-- 
2.7.4

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