[RFC PATCH 06/11] iommu/riscv: Add domain_alloc_paging_flags for second-stage domain

[fangyu.yu@linux.alibaba.com]

From: Fangyu Yu <fangyu.yu@linux.alibaba.com>

Replace .domain_alloc_paging with .domain_alloc_paging_flags so callers
can pass allocation flags to select the appropriate page-table type.

When IOMMU_HWPT_ALLOC_NEST_PARENT or IOMMU_HWPT_ALLOC_DIRTY_TRACKING is
set in @flags, allocate a second-stage (iohgatp) domain.

When @flags is 0 the behaviour is identical to the previous
domain_alloc_paging: first-stage (iosatp) domain.

Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
---
 drivers/iommu/riscv/iommu.c | 66 ++++++++++++++++++++++++++++---------
 1 file changed, 51 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index 5dadf6d09139..0c13430ecc7f 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -1255,23 +1255,50 @@ static const struct iommu_domain_ops riscv_iommu_paging_domain_ops = {
 	.flush_iotlb_all = riscv_iommu_iotlb_flush_all,
 };
 
-static struct iommu_domain *riscv_iommu_alloc_paging_domain(struct device *dev)
+static struct iommu_domain *riscv_iommu_domain_alloc_paging_flags(
+		struct device *dev, u32 flags,
+		const struct iommu_user_data *user_data)
 {
+	const bool second_stage = flags &
+		(IOMMU_HWPT_ALLOC_NEST_PARENT | IOMMU_HWPT_ALLOC_DIRTY_TRACKING);
 	struct pt_iommu_riscv_64_cfg cfg = {};
 	struct riscv_iommu_domain *domain;
 	struct riscv_iommu_device *iommu;
 	int ret;
 
+	if (user_data)
+		return ERR_PTR(-EOPNOTSUPP);
+
 	iommu = dev_to_iommu(dev);
-	if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV57) {
-		cfg.common.hw_max_vasz_lg2 = 57;
-	} else if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV48) {
-		cfg.common.hw_max_vasz_lg2 = 48;
-	} else if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV39) {
-		cfg.common.hw_max_vasz_lg2 = 39;
+
+	if (second_stage) {
+		/*
+		 * Second-stage (iohgatp) page table for KVM VFIO device
+		 * pass-through and dirty tracking. The GPA space is 2 bits
+		 * wider than the corresponding first-stage VA space (x4 root
+		 * page table), so hw_max_vasz_lg2 values are 41/50/59.
+		 */
+		if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV57X4) {
+			cfg.common.hw_max_vasz_lg2 = 59;
+		} else if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV48X4) {
+			cfg.common.hw_max_vasz_lg2 = 50;
+		} else if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV39X4) {
+			cfg.common.hw_max_vasz_lg2 = 41;
+		} else {
+			dev_err(dev, "cannot find supported second-stage page table mode\n");
+			return ERR_PTR(-ENODEV);
+		}
 	} else {
-		dev_err(dev, "cannot find supported page table mode\n");
-		return ERR_PTR(-ENODEV);
+		if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV57) {
+			cfg.common.hw_max_vasz_lg2 = 57;
+		} else if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV48) {
+			cfg.common.hw_max_vasz_lg2 = 48;
+		} else if (iommu->caps & RISCV_IOMMU_CAPABILITIES_SV39) {
+			cfg.common.hw_max_vasz_lg2 = 39;
+		} else {
+			dev_err(dev, "cannot find supported page table mode\n");
+			return ERR_PTR(-ENODEV);
+		}
 	}
 	cfg.common.hw_max_oasz_lg2 = 56;
 
@@ -1291,11 +1318,20 @@ static struct iommu_domain *riscv_iommu_alloc_paging_domain(struct device *dev)
 	domain->riscvpt.iommu.nid = dev_to_node(iommu->dev);
 	domain->domain.ops = &riscv_iommu_paging_domain_ops;
 
-	domain->pscid = ida_alloc_range(&riscv_iommu_pscids, 1,
-					RISCV_IOMMU_MAX_PSCID, GFP_KERNEL);
-	if (domain->pscid < 0) {
-		riscv_iommu_free_paging_domain(&domain->domain);
-		return ERR_PTR(-ENOMEM);
+	if (second_stage) {
+		domain->gscid = ida_alloc_range(&riscv_iommu_gscids, 1,
+						RISCV_IOMMU_MAX_GSCID, GFP_KERNEL);
+		if (domain->gscid < 0) {
+			riscv_iommu_free_paging_domain(&domain->domain);
+			return ERR_PTR(-ENOMEM);
+		}
+	} else {
+		domain->pscid = ida_alloc_range(&riscv_iommu_pscids, 1,
+						RISCV_IOMMU_MAX_PSCID, GFP_KERNEL);
+		if (domain->pscid < 0) {
+			riscv_iommu_free_paging_domain(&domain->domain);
+			return ERR_PTR(-ENOMEM);
+		}
 	}
 
 	ret = pt_iommu_riscv_64_init(&domain->riscvpt, &cfg, GFP_KERNEL);
@@ -1439,7 +1475,7 @@ static const struct iommu_ops riscv_iommu_ops = {
 	.identity_domain = &riscv_iommu_identity_domain,
 	.blocked_domain = &riscv_iommu_blocking_domain,
 	.release_domain = &riscv_iommu_blocking_domain,
-	.domain_alloc_paging = riscv_iommu_alloc_paging_domain,
+	.domain_alloc_paging_flags = riscv_iommu_domain_alloc_paging_flags,
 	.device_group = riscv_iommu_device_group,
 	.probe_device = riscv_iommu_probe_device,
 	.release_device	= riscv_iommu_release_device,
-- 
2.50.1