[PATCH RFC RESEND 6/6] iommu/riscv: support nested iommu for flushing cache

[Zong Li]

This patch implements cache_invalidate_user operation for the userspace
to flush the hardware caches for a nested domain through iommufd.

Signed-off-by: Zong Li <zong.li at sifive.com>
---
 drivers/iommu/riscv/iommu.c  | 91 ++++++++++++++++++++++++++++++++++++
 include/uapi/linux/iommufd.h |  9 ++++
 2 files changed, 100 insertions(+)

diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c
index 7eda850df475..4dd58fe2242d 100644
--- a/drivers/iommu/riscv/iommu.c
+++ b/drivers/iommu/riscv/iommu.c
@@ -1522,9 +1522,100 @@ static void riscv_iommu_domain_free_nested(struct iommu_domain *domain)
 	kfree(riscv_domain);
 }
 
+static int riscv_iommu_fix_user_cmd(struct riscv_iommu_command *cmd,
+				    unsigned int pscid, unsigned int gscid)
+{
+	u32 opcode = FIELD_GET(RISCV_IOMMU_CMD_OPCODE, cmd->dword0);
+
+	switch (opcode) {
+	case RISCV_IOMMU_CMD_IOTINVAL_OPCODE:
+		u32 func = FIELD_GET(RISCV_IOMMU_CMD_FUNC, cmd->dword0);
+
+		if (func != RISCV_IOMMU_CMD_IOTINVAL_FUNC_GVMA &&
+		    func != RISCV_IOMMU_CMD_IOTINVAL_FUNC_VMA) {
+			pr_warn("The IOTINVAL function: 0x%x is not supported\n",
+				func);
+			return -EOPNOTSUPP;
+		}
+
+		if (func == RISCV_IOMMU_CMD_IOTINVAL_FUNC_GVMA) {
+			cmd->dword0 &= ~RISCV_IOMMU_CMD_FUNC;
+			cmd->dword0 |= FIELD_PREP(RISCV_IOMMU_CMD_FUNC,
+						  RISCV_IOMMU_CMD_IOTINVAL_FUNC_VMA);
+		}
+
+		cmd->dword0 &= ~(RISCV_IOMMU_CMD_IOTINVAL_PSCID |
+				 RISCV_IOMMU_CMD_IOTINVAL_GSCID);
+		riscv_iommu_cmd_inval_set_pscid(cmd, pscid);
+		riscv_iommu_cmd_inval_set_gscid(cmd, gscid);
+		break;
+	case RISCV_IOMMU_CMD_IODIR_OPCODE:
+		/*
+		 * Ensure the device ID is right. We expect that VMM has
+		 * transferred the device ID to host's from guest's.
+		 */
+		break;
+	default:
+		pr_warn("The user command: 0x%x is not supported\n", opcode);
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int riscv_iommu_cache_invalidate_user(struct iommu_domain *domain,
+					     struct iommu_user_data_array *array)
+{
+	struct riscv_iommu_domain *riscv_domain = iommu_domain_to_riscv(domain);
+	struct riscv_iommu_device *iommu;
+	struct riscv_iommu_bond *bond;
+	struct riscv_iommu_command cmd;
+	struct iommu_hwpt_riscv_iommu_invalidate inv_info;
+	int ret, index;
+
+	if (!riscv_domain)
+		return -EINVAL;
+
+	/* Assume attached devices in the domain go through the same IOMMU device */
+	spin_lock(&riscv_domain->lock);
+	list_for_each_entry_rcu(bond, &riscv_domain->bonds, list) {
+		if (bond->dev) {
+			iommu = dev_to_iommu(bond->dev);
+			break;
+		}
+	}
+	spin_unlock(&riscv_domain->lock);
+
+	if (!iommu)
+		return -EINVAL;
+
+	for (index = 0; index < array->entry_num; index++) {
+		ret = iommu_copy_struct_from_user_array(&inv_info, array,
+							IOMMU_HWPT_DATA_RISCV_IOMMU,
+							index, cmd);
+		if (ret)
+			break;
+
+		ret = riscv_iommu_fix_user_cmd((struct riscv_iommu_command *)inv_info.cmd,
+					       riscv_domain->pscid,
+					       riscv_domain->s2->gscid);
+		if (ret == -EOPNOTSUPP)
+			continue;
+
+		riscv_iommu_cmd_send(iommu, (struct riscv_iommu_command *)inv_info.cmd, 0);
+		riscv_iommu_cmd_iofence(&cmd);
+		riscv_iommu_cmd_send(iommu, &cmd, RISCV_IOMMU_QUEUE_TIMEOUT);
+	}
+
+	array->entry_num = index;
+
+	return ret;
+}
+
 static const struct iommu_domain_ops riscv_iommu_nested_domain_ops = {
 	.attach_dev	= riscv_iommu_attach_dev_nested,
 	.free		= riscv_iommu_domain_free_nested,
+	.cache_invalidate_user = riscv_iommu_cache_invalidate_user,
 };
 
 static int
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index e10b6e236647..d93a8f11813d 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -689,6 +689,15 @@ struct iommu_hwpt_vtd_s1_invalidate {
 	__u32 __reserved;
 };
 
+/**
+ * struct iommu_hwpt_riscv_iommu_invalidate - RISCV IOMMU cache invalidation
+ *                                            (IOMMU_HWPT_TYPE_RISCV_IOMMU)
+ * @cmd: An array holds a command for cache invalidation
+ */
+struct iommu_hwpt_riscv_iommu_invalidate {
+	__aligned_u64 cmd[2];
+};
+
 /**
  * struct iommu_hwpt_invalidate - ioctl(IOMMU_HWPT_INVALIDATE)
  * @size: sizeof(struct iommu_hwpt_invalidate)
-- 
2.17.1