iommufd/selftest: Add some tests for the dmabuf flow

Basic tests of establishing a dmabuf and revoking it. The selftest kernel
side provides a basic small dmabuf for this testing.

Link: https://patch.msgid.link/r/9-v2-b2c110338e3f+5c2-iommufd_dmabuf_jgg@nvidia.com
Reviewed-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

4 files changed, 167 insertions, 0 deletions

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index a2786fee7603..ef2db82e3d7b 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -19,6 +19,8 @@ struct iommu_domain;
 struct iommu_group;
 struct iommu_option;
 struct iommufd_device;
+struct dma_buf_attachment;
+struct dma_buf_phys_vec;
 
 struct iommufd_sw_msi_map {
 	struct list_head sw_msi_item;
@@ -713,6 +715,8 @@ bool iommufd_should_fail(void);
 int __init iommufd_test_init(void);
 void iommufd_test_exit(void);
 bool iommufd_selftest_is_mock_dev(struct device *dev);
+int iommufd_test_dma_buf_iommufd_map(struct dma_buf_attachment *attachment,
+				     struct dma_buf_phys_vec *phys);
 #else
 static inline void iommufd_test_syz_conv_iova_id(struct iommufd_ucmd *ucmd,
 						 unsigned int ioas_id,
@@ -734,5 +738,11 @@ static inline bool iommufd_selftest_is_mock_dev(struct device *dev)
 {
 	return false;
 }
+static inline int
+iommufd_test_dma_buf_iommufd_map(struct dma_buf_attachment *attachment,
+				 struct dma_buf_phys_vec *phys)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 #endif
diff --git a/drivers/iommu/iommufd/iommufd_test.h b/drivers/iommu/iommufd/iommufd_test.h
index 8fc618b2bcf9..9166c39eb0c8 100644
--- a/drivers/iommu/iommufd/iommufd_test.h
+++ b/drivers/iommu/iommufd/iommufd_test.h
@@ -29,6 +29,8 @@ enum {
 	IOMMU_TEST_OP_PASID_REPLACE,
 	IOMMU_TEST_OP_PASID_DETACH,
 	IOMMU_TEST_OP_PASID_CHECK_HWPT,
+	IOMMU_TEST_OP_DMABUF_GET,
+	IOMMU_TEST_OP_DMABUF_REVOKE,
 };
 
 enum {
@@ -176,6 +178,14 @@ struct iommu_test_cmd {
 			__u32 hwpt_id;
 			/* @id is stdev_id */
 		} pasid_check;
+		struct {
+			__u32 length;
+			__u32 open_flags;
+		} dmabuf_get;
+		struct {
+			__s32 dmabuf_fd;
+			__u32 revoked;
+		} dmabuf_revoke;
 	};
 	__u32 last;
 };
diff --git a/drivers/iommu/iommufd/pages.c b/drivers/iommu/iommufd/pages.c
index c73456833d04..dbe51ecb9a20 100644
--- a/drivers/iommu/iommufd/pages.c
+++ b/drivers/iommu/iommufd/pages.c
@@ -1465,6 +1465,10 @@ sym_vfio_pci_dma_buf_iommufd_map(struct dma_buf_attachment *attachment,
 	typeof(&vfio_pci_dma_buf_iommufd_map) fn;
 	int rc;
 
+	rc = iommufd_test_dma_buf_iommufd_map(attachment, phys);
+	if (rc != -EOPNOTSUPP)
+		return rc;
+
 	if (!IS_ENABLED(CONFIG_VFIO_PCI_DMABUF))
 		return -EOPNOTSUPP;
 
diff --git a/drivers/iommu/iommufd/selftest.c b/drivers/iommu/iommufd/selftest.c
index de178827a078..5d14dd0fb37d 100644
--- a/drivers/iommu/iommufd/selftest.c
+++ b/drivers/iommu/iommufd/selftest.c
@@ -5,6 +5,8 @@
  */
 #include <linux/anon_inodes.h>
 #include <linux/debugfs.h>
+#include <linux/dma-buf.h>
+#include <linux/dma-resv.h>
 #include <linux/fault-inject.h>
 #include <linux/file.h>
 #include <linux/iommu.h>
@@ -2031,6 +2033,140 @@ void iommufd_selftest_destroy(struct iommufd_object *obj)
 	}
 }
 
+struct iommufd_test_dma_buf {
+	void *memory;
+	size_t length;
+	bool revoked;
+};
+
+static int iommufd_test_dma_buf_attach(struct dma_buf *dmabuf,
+				       struct dma_buf_attachment *attachment)
+{
+	return 0;
+}
+
+static void iommufd_test_dma_buf_detach(struct dma_buf *dmabuf,
+					struct dma_buf_attachment *attachment)
+{
+}
+
+static struct sg_table *
+iommufd_test_dma_buf_map(struct dma_buf_attachment *attachment,
+			 enum dma_data_direction dir)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static void iommufd_test_dma_buf_unmap(struct dma_buf_attachment *attachment,
+				       struct sg_table *sgt,
+				       enum dma_data_direction dir)
+{
+}
+
+static void iommufd_test_dma_buf_release(struct dma_buf *dmabuf)
+{
+	struct iommufd_test_dma_buf *priv = dmabuf->priv;
+
+	kfree(priv->memory);
+	kfree(priv);
+}
+
+static const struct dma_buf_ops iommufd_test_dmabuf_ops = {
+	.attach = iommufd_test_dma_buf_attach,
+	.detach = iommufd_test_dma_buf_detach,
+	.map_dma_buf = iommufd_test_dma_buf_map,
+	.release = iommufd_test_dma_buf_release,
+	.unmap_dma_buf = iommufd_test_dma_buf_unmap,
+};
+
+int iommufd_test_dma_buf_iommufd_map(struct dma_buf_attachment *attachment,
+				     struct dma_buf_phys_vec *phys)
+{
+	struct iommufd_test_dma_buf *priv = attachment->dmabuf->priv;
+
+	dma_resv_assert_held(attachment->dmabuf->resv);
+
+	if (attachment->dmabuf->ops != &iommufd_test_dmabuf_ops)
+		return -EOPNOTSUPP;
+
+	if (priv->revoked)
+		return -ENODEV;
+
+	phys->paddr = virt_to_phys(priv->memory);
+	phys->len = priv->length;
+	return 0;
+}
+
+static int iommufd_test_dmabuf_get(struct iommufd_ucmd *ucmd,
+				   unsigned int open_flags,
+				   size_t len)
+{
+	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
+	struct iommufd_test_dma_buf *priv;
+	struct dma_buf *dmabuf;
+	int rc;
+
+	len = ALIGN(len, PAGE_SIZE);
+	if (len == 0 || len > PAGE_SIZE * 512)
+		return -EINVAL;
+
+	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->length = len;
+	priv->memory = kzalloc(len, GFP_KERNEL);
+	if (!priv->memory) {
+		rc = -ENOMEM;
+		goto err_free;
+	}
+
+	exp_info.ops = &iommufd_test_dmabuf_ops;
+	exp_info.size = len;
+	exp_info.flags = open_flags;
+	exp_info.priv = priv;
+
+	dmabuf = dma_buf_export(&exp_info);
+	if (IS_ERR(dmabuf)) {
+		rc = PTR_ERR(dmabuf);
+		goto err_free;
+	}
+
+	return dma_buf_fd(dmabuf, open_flags);
+
+err_free:
+	kfree(priv->memory);
+	kfree(priv);
+	return rc;
+}
+
+static int iommufd_test_dmabuf_revoke(struct iommufd_ucmd *ucmd, int fd,
+				      bool revoked)
+{
+	struct iommufd_test_dma_buf *priv;
+	struct dma_buf *dmabuf;
+	int rc = 0;
+
+	dmabuf = dma_buf_get(fd);
+	if (IS_ERR(dmabuf))
+		return PTR_ERR(dmabuf);
+
+	if (dmabuf->ops != &iommufd_test_dmabuf_ops) {
+		rc = -EOPNOTSUPP;
+		goto err_put;
+	}
+
+	priv = dmabuf->priv;
+	dma_resv_lock(dmabuf->resv, NULL);
+	priv->revoked = revoked;
+	dma_buf_move_notify(dmabuf);
+	dma_resv_unlock(dmabuf->resv);
+
+err_put:
+	dma_buf_put(dmabuf);
+	return rc;
+}
+
 int iommufd_test(struct iommufd_ucmd *ucmd)
 {
 	struct iommu_test_cmd *cmd = ucmd->cmd;
@@ -2109,6 +2245,13 @@ int iommufd_test(struct iommufd_ucmd *ucmd)
 		return iommufd_test_pasid_detach(ucmd, cmd);
 	case IOMMU_TEST_OP_PASID_CHECK_HWPT:
 		return iommufd_test_pasid_check_hwpt(ucmd, cmd);
+	case IOMMU_TEST_OP_DMABUF_GET:
+		return iommufd_test_dmabuf_get(ucmd, cmd->dmabuf_get.open_flags,
+					       cmd->dmabuf_get.length);
+	case IOMMU_TEST_OP_DMABUF_REVOKE:
+		return iommufd_test_dmabuf_revoke(ucmd,
+						  cmd->dmabuf_revoke.dmabuf_fd,
+						  cmd->dmabuf_revoke.revoked);
 	default:
 		return -EOPNOTSUPP;
 	}