[PATCH v4 02/15] iommu: Report domain nesting info

[Liu Yi L]

IOMMUs that support nesting translation needs report the capability info
to userspace, e.g. the format of first level/stage paging structures.

This patch reports nesting info by DOMAIN_ATTR_NESTING. Caller can get
nesting info after setting DOMAIN_ATTR_NESTING.

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>
---
v3 -> v4:
*) split the SMMU driver changes to be a separate patch
*) move the @addr_width and @pasid_bits from vendor specific
   part to generic part.
*) tweak the description for the @features field of struct
   iommu_nesting_info.
*) add description on the @data[] field of struct iommu_nesting_info

v2 -> v3:
*) remvoe cap/ecap_mask in iommu_nesting_info.
*) reuse DOMAIN_ATTR_NESTING to get nesting info.
*) return an empty iommu_nesting_info for SMMU drivers per Jean'
   suggestion.
---
 include/uapi/linux/iommu.h | 78 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)

diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
index 1afc661..1bfc032 100644
--- a/include/uapi/linux/iommu.h
+++ b/include/uapi/linux/iommu.h
@@ -332,4 +332,82 @@ struct iommu_gpasid_bind_data {
 	} vendor;
 };
 
+/*
+ * struct iommu_nesting_info - Information for nesting-capable IOMMU.
+ *				user space should check it before using
+ *				nesting capability.
+ *
+ * @size:	size of the whole structure
+ * @format:	PASID table entry format, the same definition with
+ *		@format of struct iommu_gpasid_bind_data.
+ * @features:	supported nesting features.
+ * @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.
+ * @data:	vendor specific cap info. data[] structure type can be deduced
+ *		from @format field.
+ *
+ * +===============+======================================================+
+ * | feature       |  Notes                                               |
+ * +===============+======================================================+
+ * | SYSWIDE_PASID |  PASIDs are managed in system-wide, instead of per   |
+ * |               |  device. When a device is assigned to userspace or   |
+ * |               |  VM, proper uAPI (userspace driver framework uAPI,   |
+ * |               |  e.g. VFIO) must be used to allocate/free PASIDs for |
+ * |               |  the assigned device.                                |
+ * +---------------+------------------------------------------------------+
+ * | BIND_PGTBL    |  The owner of the first level/stage page table must  |
+ * |               |  explicitly bind the page table to associated PASID  |
+ * |               |  (either the one specified in bind request or the    |
+ * |               |  default PASID of iommu domain), through userspace   |
+ * |               |  driver framework uAPI (e.g. VFIO_IOMMU_NESTING_OP). |
+ * +---------------+------------------------------------------------------+
+ * | CACHE_INVLD   |  The owner of the first level/stage page table must  |
+ * |               |  explicitly invalidate the IOMMU cache through uAPI  |
+ * |               |  provided by userspace driver framework (e.g. VFIO)  |
+ * |               |  according to vendor-specific requirement when       |
+ * |               |  changing the page table.                            |
+ * +---------------+------------------------------------------------------+
+ *
+ * @data[] types defined for @format:
+ * +================================+=====================================+
+ * | @format                        | @data[]                             |
+ * +================================+=====================================+
+ * | IOMMU_PASID_FORMAT_INTEL_VTD   | struct iommu_nesting_info_vtd       |
+ * +--------------------------------+-------------------------------------+
+ *
+ */
+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;
+	__u16	addr_width;
+	__u16	pasid_bits;
+	__u32	padding;
+	__u8	data[];
+};
+
+/*
+ * struct iommu_nesting_info_vtd - Intel VT-d specific nesting info
+ *
+ *
+ * @flags:	VT-d specific flags. Currently reserved for future
+ *		extension.
+ * @cap_reg:	Describe basic capabilities as defined in VT-d capability
+ *		register.
+ * @ecap_reg:	Describe the extended capabilities as defined in VT-d
+ *		extended capability register.
+ */
+struct iommu_nesting_info_vtd {
+	__u32	flags;
+	__u32	padding;
+	__u64	cap_reg;
+	__u64	ecap_reg;
+};
+
 #endif /* _UAPI_IOMMU_H */
-- 
2.7.4