[PATCH v3 02/14] iommu: Report domain nesting info

[Liu Yi L <yi.l.liu@intel.com>]

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.

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.

Cc: Kevin Tian <kevin.tian@intel.com>
CC: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Eric Auger <eric.auger@redhat.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 drivers/iommu/arm-smmu-v3.c | 29 ++++++++++++++++++++--
 drivers/iommu/arm-smmu.c    | 29 ++++++++++++++++++++--
 include/uapi/linux/iommu.h  | 59 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 113 insertions(+), 4 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index f578677..0c45d4d 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -3019,6 +3019,32 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev)
 	return group;
 }
 
+static int arm_smmu_domain_nesting_info(struct arm_smmu_domain *smmu_domain,
+					void *data)
+{
+	struct iommu_nesting_info *info = (struct iommu_nesting_info *) data;
+	u32 size;
+
+	if (!info || smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
+		return -ENODEV;
+
+	size = sizeof(struct iommu_nesting_info);
+
+	/*
+	 * if provided buffer size is not equal to the size, should
+	 * return 0 and also the expected buffer size to caller.
+	 */
+	if (info->size != size) {
+		info->size = size;
+		return 0;
+	}
+
+	/* report an empty iommu_nesting_info for now */
+	memset(info, 0x0, size);
+	info->size = size;
+	return 0;
+}
+
 static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
 				    enum iommu_attr attr, void *data)
 {
@@ -3028,8 +3054,7 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
 	case IOMMU_DOMAIN_UNMANAGED:
 		switch (attr) {
 		case DOMAIN_ATTR_NESTING:
-			*(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED);
-			return 0;
+			return arm_smmu_domain_nesting_info(smmu_domain, data);
 		default:
 			return -ENODEV;
 		}
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 243bc4c..908607d 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -1506,6 +1506,32 @@ static struct iommu_group *arm_smmu_device_group(struct device *dev)
 	return group;
 }
 
+static int arm_smmu_domain_nesting_info(struct arm_smmu_domain *smmu_domain,
+					void *data)
+{
+	struct iommu_nesting_info *info = (struct iommu_nesting_info *) data;
+	u32 size;
+
+	if (!info || smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
+		return -ENODEV;
+
+	size = sizeof(struct iommu_nesting_info);
+
+	/*
+	 * if provided buffer size is not equal to the size, should
+	 * return 0 and also the expected buffer size to caller.
+	 */
+	if (info->size != size) {
+		info->size = size;
+		return 0;
+	}
+
+	/* report an empty iommu_nesting_info for now */
+	memset(info, 0x0, size);
+	info->size = size;
+	return 0;
+}
+
 static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
 				    enum iommu_attr attr, void *data)
 {
@@ -1515,8 +1541,7 @@ static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
 	case IOMMU_DOMAIN_UNMANAGED:
 		switch (attr) {
 		case DOMAIN_ATTR_NESTING:
-			*(int *)data = (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED);
-			return 0;
+			return arm_smmu_domain_nesting_info(smmu_domain, data);
 		default:
 			return -ENODEV;
 		}
diff --git a/include/uapi/linux/iommu.h b/include/uapi/linux/iommu.h
index 1afc661..898c99a 100644
--- a/include/uapi/linux/iommu.h
+++ b/include/uapi/linux/iommu.h
@@ -332,4 +332,63 @@ 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.
+ * @data:	vendor specific cap info.
+ *
+ * +---------------+----------------------------------------------------+
+ * | feature       |  Notes                                             |
+ * +===============+====================================================+
+ * | SYSWIDE_PASID |  Kernel manages PASID in system wide, PASIDs used  |
+ * |               |  in the system should be allocated by host kernel  |
+ * +---------------+----------------------------------------------------+
+ * | BIND_PGTBL    |  bind page tables to host PASID, the PASID could   |
+ * |               |  either be a host PASID passed in bind request or  |
+ * |               |  default PASIDs (e.g. default PASID of aux-domain) |
+ * +---------------+----------------------------------------------------+
+ * | CACHE_INVLD   |  mandatory feature for nesting capable IOMMU       |
+ * +---------------+----------------------------------------------------+
+ *
+ */
+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[];
+};
+
+/*
+ * struct iommu_nesting_info_vtd - Intel VT-d specific nesting info
+ *
+ *
+ * @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.
+ * @ecap_reg:	Describe the extended capabilities as defined in VT-d
+ *		extended capability register.
+ */
+struct iommu_nesting_info_vtd {
+	__u32	flags;
+	__u16	addr_width;
+	__u16	pasid_bits;
+	__u64	cap_reg;
+	__u64	ecap_reg;
+};
+
 #endif /* _UAPI_IOMMU_H */
-- 
2.7.4

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