[PATCH 00/11] iommufd: Enable noiommu mode for cdev

[PATCH 00/11] iommufd: Enable noiommu mode for cdev

[Jacob Pan]

VFIO's unsafe_noiommu_mode has long provided a way for userspace drivers
to operate on platforms lacking a hardware IOMMU. Today, IOMMUFD also
supports No-IOMMU mode for group-based devices under vfio_compat mode.
However, IOMMUFD's native character device (cdev) does not yet support
No-IOMMU mode, which is the purpose of this patch.

In summary, we have:

|-------------------------+------+---------------|
| Device access mode      | VFIO | IOMMUFD       |
|-------------------------+------+---------------|
| group /dev/vfio/$GROUP  | Yes  | Yes           |
|-------------------------+------+---------------|
| cdev /dev/vfio/devices/ | No   | This patch    |
|-------------------------+------+---------------|

Beyond enabling cdev for IOMMUFD, this patch also addresses the following
deficiencies in the current No-IOMMU mode suggested by Jason[1]:
- Devices operating under No-IOMMU mode are limited to device-level UAPI
  access, without container or IOAS-level capabilities. Consequently,
  user-space drivers lack structured mechanisms for page pinning and often
  resort to mlock(), which is less robust than pin_user_pages() used for
  devices backed by a physical IOMMU. For example, mlock() does not prevent
  page migration.
- There is no architectural mechanism for obtaining physical addresses for
  DMA. As a workaround, user-space drivers frequently rely on /proc/pagemap
  tricks or hardcoded values.

By allowing noiommu device access to IOMMUFD IOAS and HWPT objects, this
patch brings No-IOMMU mode closer to full citizenship within the IOMMU
subsystem. In addition to addressing the two deficiencies mentioned above,
the expectation is that it will also enable No-IOMMU devices to seamlessly
participate in live update sessions via KHO [2].

Furthermore, these devices will use the IOMMUFD-based ownership checking model for
VFIO_DEVICE_PCI_HOT_RESET, eliminating the need for an iommufd_access object
as required in a previous attempt [3].

ChangeLog:

Since RFC[4]:
- Abandoned dummy iommu driver approach as patch 1-3 absorbed the
  changes into iommufd.

[1] https://lore.kernel.org/linux-iommu/20250603175403.GA407344@nvidia.com/
[2] https://lore.kernel.org/linux-pci/20251027134430.00007e46@linux.microsoft.com/
[3] https://lore.kernel.org/kvm/20230522115751.326947-1-yi.l.liu@intel.com/
[4] https://lore.kernel.org/linux-iommu/20251201173012.18371-1-jacob.pan@linux.microsoft.com/

Thanks,

Jacob

Jacob Pan (8):
  iommufd: Add an ioctl IOMMU_IOAS_GET_PA to query PA from IOVA
  vfio: Allow null group for noiommu without containers
  vfio: Introduce and set noiommu flag on vfio_device
  vfio: Update noiommu device detection logic for cdev
  vfio: Enable cdev noiommu mode under iommufd
  vfio:selftest: Handle VFIO noiommu cdev
  selftests/vfio: Add iommufd noiommu mode selftest for cdev
  Doc: Update VFIO NOIOMMU mode

Jason Gunthorpe (3):
  iommufd: Support a HWPT without an iommu driver for noiommu
  iommufd: Move igroup allocation to a function
  iommufd: Allow binding to a noiommu device

 Documentation/driver-api/vfio.rst             |  44 +-
 drivers/iommu/iommufd/Makefile                |   1 +
 drivers/iommu/iommufd/device.c                | 161 ++++--
 drivers/iommu/iommufd/hw_pagetable.c          |  11 +-
 drivers/iommu/iommufd/hwpt_noiommu.c          |  91 +++
 drivers/iommu/iommufd/io_pagetable.c          |  39 ++
 drivers/iommu/iommufd/ioas.c                  |  22 +
 drivers/iommu/iommufd/iommufd_private.h       |   5 +
 drivers/iommu/iommufd/main.c                  |   3 +
 drivers/vfio/Kconfig                          |   6 +-
 drivers/vfio/group.c                          |  35 +-
 drivers/vfio/iommufd.c                        |   7 -
 drivers/vfio/vfio.h                           |  34 +-
 drivers/vfio/vfio_main.c                      |  22 +-
 include/linux/vfio.h                          |  10 +
 include/uapi/linux/iommufd.h                  |  25 +
 tools/testing/selftests/vfio/Makefile         |   1 +
 .../selftests/vfio/lib/vfio_pci_device.c      |  25 +-
 .../vfio/vfio_iommufd_noiommu_test.c          | 540 ++++++++++++++++++
 19 files changed, 990 insertions(+), 92 deletions(-)
 create mode 100644 drivers/iommu/iommufd/hwpt_noiommu.c
 create mode 100644 tools/testing/selftests/vfio/vfio_iommufd_noiommu_test.c

-- 
2.34.1

[PATCH 01/11] iommufd: Support a HWPT without an iommu driver for noiommu

[Jacob Pan]

From: Jason Gunthorpe <jgg@nvidia.com>

Create just a little part of a real iommu driver, enough to
slot in under the dev_iommu_ops() and allow iommufd to call
domain_alloc_paging_flags() and fail everything else.

This allows explicitly creating a HWPT under an IOAS.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 drivers/iommu/iommufd/Makefile          |  1 +
 drivers/iommu/iommufd/hw_pagetable.c    | 11 ++-
 drivers/iommu/iommufd/hwpt_noiommu.c    | 91 +++++++++++++++++++++++++
 drivers/iommu/iommufd/iommufd_private.h |  2 +
 4 files changed, 103 insertions(+), 2 deletions(-)
 create mode 100644 drivers/iommu/iommufd/hwpt_noiommu.c

diff --git a/drivers/iommu/iommufd/Makefile b/drivers/iommu/iommufd/Makefile
index 71d692c9a8f4..2b1a020b14a6 100644
--- a/drivers/iommu/iommufd/Makefile
+++ b/drivers/iommu/iommufd/Makefile
@@ -10,6 +10,7 @@ iommufd-y := \
 	vfio_compat.o \
 	viommu.o
 
+iommufd-$(CONFIG_VFIO_NOIOMMU) += hwpt_noiommu.o
 iommufd-$(CONFIG_IOMMUFD_TEST) += selftest.o
 
 obj-$(CONFIG_IOMMUFD) += iommufd.o
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index fe789c2dc0c9..37316d77277d 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -8,6 +8,13 @@
 #include "../iommu-priv.h"
 #include "iommufd_private.h"
 
+static const struct iommu_ops *get_iommu_ops(struct iommufd_device *idev)
+{
+	if (IS_ENABLED(CONFIG_VFIO_NOIOMMU) && !idev->igroup->group)
+		return &iommufd_noiommu_ops;
+	return dev_iommu_ops(idev->dev);
+}
+
 static void __iommufd_hwpt_destroy(struct iommufd_hw_pagetable *hwpt)
 {
 	if (hwpt->domain)
@@ -114,7 +121,7 @@ iommufd_hwpt_paging_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 				IOMMU_HWPT_ALLOC_DIRTY_TRACKING |
 				IOMMU_HWPT_FAULT_ID_VALID |
 				IOMMU_HWPT_ALLOC_PASID;
-	const struct iommu_ops *ops = dev_iommu_ops(idev->dev);
+	const struct iommu_ops *ops = get_iommu_ops(idev);
 	struct iommufd_hwpt_paging *hwpt_paging;
 	struct iommufd_hw_pagetable *hwpt;
 	int rc;
@@ -229,7 +236,7 @@ iommufd_hwpt_nested_alloc(struct iommufd_ctx *ictx,
 			  struct iommufd_device *idev, u32 flags,
 			  const struct iommu_user_data *user_data)
 {
-	const struct iommu_ops *ops = dev_iommu_ops(idev->dev);
+	const struct iommu_ops *ops = get_iommu_ops(idev);
 	struct iommufd_hwpt_nested *hwpt_nested;
 	struct iommufd_hw_pagetable *hwpt;
 	int rc;
diff --git a/drivers/iommu/iommufd/hwpt_noiommu.c b/drivers/iommu/iommufd/hwpt_noiommu.c
new file mode 100644
index 000000000000..0aa99f581ca3
--- /dev/null
+++ b/drivers/iommu/iommufd/hwpt_noiommu.c
@@ -0,0 +1,91 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
+ */
+#include <linux/iommu.h>
+#include <linux/generic_pt/iommu.h>
+#include "iommufd_private.h"
+
+static const struct iommu_domain_ops noiommu_amdv1_ops;
+
+struct noiommu_domain {
+	union {
+		struct iommu_domain domain;
+		struct pt_iommu_amdv1 amdv1;
+	};
+	spinlock_t lock;
+};
+PT_IOMMU_CHECK_DOMAIN(struct noiommu_domain, amdv1.iommu, domain);
+
+static void noiommu_change_top(struct pt_iommu *iommu_table,
+			       phys_addr_t top_paddr, unsigned int top_level)
+{
+}
+
+static spinlock_t *noiommu_get_top_lock(struct pt_iommu *iommupt)
+{
+	struct noiommu_domain *domain =
+		container_of(iommupt, struct noiommu_domain, amdv1.iommu);
+
+	return &domain->lock;
+}
+
+static const struct pt_iommu_driver_ops noiommu_driver_ops = {
+	.get_top_lock = noiommu_get_top_lock,
+	.change_top = noiommu_change_top,
+};
+
+static struct iommu_domain *
+noiommu_alloc_paging_flags(struct device *dev, u32 flags,
+			   const struct iommu_user_data *user_data)
+{
+	struct pt_iommu_amdv1_cfg cfg = {};
+	struct noiommu_domain *dom;
+	int rc;
+
+	if (flags || user_data)
+		return ERR_PTR(-EOPNOTSUPP);
+
+	cfg.common.hw_max_vasz_lg2 = 64;
+	cfg.common.hw_max_oasz_lg2 = 52;
+	cfg.starting_level = 2;
+	cfg.common.features =
+		(BIT(PT_FEAT_DYNAMIC_TOP) | BIT(PT_FEAT_AMDV1_ENCRYPT_TABLES) |
+		 BIT(PT_FEAT_AMDV1_FORCE_COHERENCE));
+
+	dom = kzalloc(sizeof(*dom), GFP_KERNEL);
+	if (!dom)
+		return ERR_PTR(-ENOMEM);
+
+	spin_lock_init(&dom->lock);
+	dom->amdv1.iommu.nid = NUMA_NO_NODE;
+	dom->amdv1.iommu.driver_ops = &noiommu_driver_ops;
+	dom->domain.ops = &noiommu_amdv1_ops;
+
+	/* Use mock page table which is based on AMDV1 */
+	rc = pt_iommu_amdv1_init(&dom->amdv1, &cfg, GFP_KERNEL);
+	if (rc) {
+		kfree(dom);
+		return ERR_PTR(rc);
+	}
+
+	return &dom->domain;
+}
+
+static void noiommu_domain_free(struct iommu_domain *iommu_domain)
+{
+	struct noiommu_domain *domain =
+		container_of(iommu_domain, struct noiommu_domain, domain);
+
+	pt_iommu_deinit(&domain->amdv1.iommu);
+	kfree(domain);
+}
+
+static const struct iommu_domain_ops noiommu_amdv1_ops = {
+	IOMMU_PT_DOMAIN_OPS(amdv1),
+	.free = noiommu_domain_free,
+};
+
+struct iommu_ops iommufd_noiommu_ops = {
+	.domain_alloc_paging_flags = noiommu_alloc_paging_flags,
+};
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 6ac1965199e9..9c18c5eb1899 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -464,6 +464,8 @@ static inline void iommufd_hw_pagetable_put(struct iommufd_ctx *ictx,
 	refcount_dec(&hwpt->obj.users);
 }
 
+extern struct iommu_ops iommufd_noiommu_ops;
+
 struct iommufd_attach;
 
 struct iommufd_group {
-- 
2.34.1

[PATCH 02/11] iommufd: Move igroup allocation to a function

[Jacob Pan]

From: Jason Gunthorpe <jgg@nvidia.com>

So it can be reused in the next patch which allows binding to noiommu
device.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 drivers/iommu/iommufd/device.c | 48 +++++++++++++++++++++-------------
 1 file changed, 30 insertions(+), 18 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 344d620cdecc..54d73016468f 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -30,8 +30,9 @@ static void iommufd_group_release(struct kref *kref)
 
 	WARN_ON(!xa_empty(&igroup->pasid_attach));
 
-	xa_cmpxchg(&igroup->ictx->groups, iommu_group_id(igroup->group), igroup,
-		   NULL, GFP_KERNEL);
+	if (igroup->group)
+		xa_cmpxchg(&igroup->ictx->groups, iommu_group_id(igroup->group),
+			   igroup, NULL, GFP_KERNEL);
 	iommu_group_put(igroup->group);
 	mutex_destroy(&igroup->lock);
 	kfree(igroup);
@@ -56,6 +57,30 @@ static bool iommufd_group_try_get(struct iommufd_group *igroup,
 	return kref_get_unless_zero(&igroup->ref);
 }
 
+static struct iommufd_group *iommufd_alloc_group(struct iommufd_ctx *ictx,
+						 struct iommu_group *group)
+{
+	struct iommufd_group *new_igroup;
+
+	new_igroup = kzalloc(sizeof(*new_igroup), GFP_KERNEL);
+	if (!new_igroup)
+		return ERR_PTR(-ENOMEM);
+
+	kref_init(&new_igroup->ref);
+	mutex_init(&new_igroup->lock);
+	xa_init(&new_igroup->pasid_attach);
+	new_igroup->sw_msi_start = PHYS_ADDR_MAX;
+	/* group reference moves into new_igroup */
+	new_igroup->group = group;
+
+	/*
+	 * The ictx is not additionally refcounted here becase all objects using
+	 * an igroup must put it before their destroy completes.
+	 */
+	new_igroup->ictx = ictx;
+	return new_igroup;
+}
+
 /*
  * iommufd needs to store some more data for each iommu_group, we keep a
  * parallel xarray indexed by iommu_group id to hold this instead of putting it
@@ -87,25 +112,12 @@ static struct iommufd_group *iommufd_get_group(struct iommufd_ctx *ictx,
 	}
 	xa_unlock(&ictx->groups);
 
-	new_igroup = kzalloc_obj(*new_igroup);
-	if (!new_igroup) {
+	new_igroup = iommufd_alloc_group(ictx, group);
+	if (IS_ERR(new_igroup)) {
 		iommu_group_put(group);
-		return ERR_PTR(-ENOMEM);
+		return new_igroup;
 	}
 
-	kref_init(&new_igroup->ref);
-	mutex_init(&new_igroup->lock);
-	xa_init(&new_igroup->pasid_attach);
-	new_igroup->sw_msi_start = PHYS_ADDR_MAX;
-	/* group reference moves into new_igroup */
-	new_igroup->group = group;
-
-	/*
-	 * The ictx is not additionally refcounted here becase all objects using
-	 * an igroup must put it before their destroy completes.
-	 */
-	new_igroup->ictx = ictx;
-
 	/*
 	 * We dropped the lock so igroup is invalid. NULL is a safe and likely
 	 * value to assume for the xa_cmpxchg algorithm.
-- 
2.34.1

[PATCH 03/11] iommufd: Allow binding to a noiommu device

[Jacob Pan]

From: Jason Gunthorpe <jgg@nvidia.com>

Allow iommufd to bind devices without an IOMMU (noiommu mode) by creating
a dummy IOMMU group for such devices and skipping hwpt operations.

This enables noiommu devices to operate through the same iommufd API as IOMMU-
capable devices.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 drivers/iommu/iommufd/device.c | 113 ++++++++++++++++++++++-----------
 1 file changed, 76 insertions(+), 37 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 54d73016468f..c38d3efa3d6f 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -23,6 +23,11 @@ struct iommufd_attach {
 	struct xarray device_array;
 };
 
+static bool is_vfio_noiommu(struct iommufd_device *idev)
+{
+	return !device_iommu_mapped(idev->dev) || !idev->dev->iommu;
+}
+
 static void iommufd_group_release(struct kref *kref)
 {
 	struct iommufd_group *igroup =
@@ -205,32 +210,17 @@ void iommufd_device_destroy(struct iommufd_object *obj)
 	struct iommufd_device *idev =
 		container_of(obj, struct iommufd_device, obj);
 
-	iommu_device_release_dma_owner(idev->dev);
+	if (!is_vfio_noiommu(idev))
+		iommu_device_release_dma_owner(idev->dev);
 	iommufd_put_group(idev->igroup);
 	if (!iommufd_selftest_is_mock_dev(idev->dev))
 		iommufd_ctx_put(idev->ictx);
 }
 
-/**
- * iommufd_device_bind - Bind a physical device to an iommu fd
- * @ictx: iommufd file descriptor
- * @dev: Pointer to a physical device struct
- * @id: Output ID number to return to userspace for this device
- *
- * A successful bind establishes an ownership over the device and returns
- * struct iommufd_device pointer, otherwise returns error pointer.
- *
- * A driver using this API must set driver_managed_dma and must not touch
- * the device until this routine succeeds and establishes ownership.
- *
- * Binding a PCI device places the entire RID under iommufd control.
- *
- * The caller must undo this with iommufd_device_unbind()
- */
-struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
-					   struct device *dev, u32 *id)
+static int iommufd_bind_iommu(struct iommufd_device *idev)
 {
-	struct iommufd_device *idev;
+	struct iommufd_ctx *ictx = idev->ictx;
+	struct device *dev = idev->dev;
 	struct iommufd_group *igroup;
 	int rc;
 
@@ -239,11 +229,11 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
 	 * to restore cache coherency.
 	 */
 	if (!device_iommu_capable(dev, IOMMU_CAP_CACHE_COHERENCY))
-		return ERR_PTR(-EINVAL);
+		return -EINVAL;
 
-	igroup = iommufd_get_group(ictx, dev);
+	igroup = iommufd_get_group(idev->ictx, dev);
 	if (IS_ERR(igroup))
-		return ERR_CAST(igroup);
+		return PTR_ERR(igroup);
 
 	/*
 	 * For historical compat with VFIO the insecure interrupt path is
@@ -269,21 +259,66 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
 	if (rc)
 		goto out_group_put;
 
+	/* igroup refcount moves into iommufd_device */
+	idev->igroup = igroup;
+	return 0;
+
+out_group_put:
+	iommufd_put_group(igroup);
+	return rc;
+}
+
+/**
+ * iommufd_device_bind - Bind a physical device to an iommu fd
+ * @ictx: iommufd file descriptor
+ * @dev: Pointer to a physical device struct
+ * @id: Output ID number to return to userspace for this device
+ *
+ * A successful bind establishes an ownership over the device and returns
+ * struct iommufd_device pointer, otherwise returns error pointer.
+ *
+ * A driver using this API must set driver_managed_dma and must not touch
+ * the device until this routine succeeds and establishes ownership.
+ *
+ * Binding a PCI device places the entire RID under iommufd control.
+ *
+ * The caller must undo this with iommufd_device_unbind()
+ */
+struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
+					   struct device *dev, u32 *id)
+{
+	struct iommufd_device *idev;
+	int rc;
+
 	idev = iommufd_object_alloc(ictx, idev, IOMMUFD_OBJ_DEVICE);
-	if (IS_ERR(idev)) {
-		rc = PTR_ERR(idev);
-		goto out_release_owner;
-	}
+	if (IS_ERR(idev))
+		return idev;
 	idev->ictx = ictx;
-	if (!iommufd_selftest_is_mock_dev(dev))
-		iommufd_ctx_get(ictx);
 	idev->dev = dev;
 	idev->enforce_cache_coherency =
 		device_iommu_capable(dev, IOMMU_CAP_ENFORCE_CACHE_COHERENCY);
+
+	if (!is_vfio_noiommu(idev)) {
+		rc = iommufd_bind_iommu(idev);
+		if (rc)
+			return ERR_PTR(rc);
+	} else {
+		struct iommufd_group *igroup;
+
+		/*
+		 * Create a dummy igroup, lots of stuff expects ths igroup to be
+		 * present, but a NULL igroup->group is OK
+		 */
+		igroup = iommufd_alloc_group(ictx, NULL);
+		if (IS_ERR(igroup))
+			return ERR_CAST(igroup);
+		idev->igroup = igroup;
+	}
+
+	if (!iommufd_selftest_is_mock_dev(dev))
+		iommufd_ctx_get(ictx);
 	/* The calling driver is a user until iommufd_device_unbind() */
 	refcount_inc(&idev->obj.users);
-	/* igroup refcount moves into iommufd_device */
-	idev->igroup = igroup;
 
 	/*
 	 * If the caller fails after this success it must call
@@ -295,11 +330,6 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
 	*id = idev->obj.id;
 	return idev;
 
-out_release_owner:
-	iommu_device_release_dma_owner(dev);
-out_group_put:
-	iommufd_put_group(igroup);
-	return ERR_PTR(rc);
 }
 EXPORT_SYMBOL_NS_GPL(iommufd_device_bind, "IOMMUFD");
 
@@ -513,6 +543,9 @@ static int iommufd_hwpt_attach_device(struct iommufd_hw_pagetable *hwpt,
 	struct iommufd_attach_handle *handle;
 	int rc;
 
+	if (is_vfio_noiommu(idev))
+		return 0;
+
 	if (!iommufd_hwpt_compatible_device(hwpt, idev))
 		return -EINVAL;
 
@@ -560,6 +593,9 @@ static void iommufd_hwpt_detach_device(struct iommufd_hw_pagetable *hwpt,
 {
 	struct iommufd_attach_handle *handle;
 
+	if (is_vfio_noiommu(idev))
+		return;
+
 	handle = iommufd_device_get_attach_handle(idev, pasid);
 	if (pasid == IOMMU_NO_PASID)
 		iommu_detach_group_handle(hwpt->domain, idev->igroup->group);
@@ -578,6 +614,9 @@ static int iommufd_hwpt_replace_device(struct iommufd_device *idev,
 	struct iommufd_attach_handle *handle, *old_handle;
 	int rc;
 
+	if (is_vfio_noiommu(idev))
+		return 0;
+
 	if (!iommufd_hwpt_compatible_device(hwpt, idev))
 		return -EINVAL;
 
@@ -653,7 +692,7 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 		goto err_release_devid;
 	}
 
-	if (attach_resv) {
+	if (attach_resv && !is_vfio_noiommu(idev)) {
 		rc = iommufd_device_attach_reserved_iova(idev, hwpt_paging);
 		if (rc)
 			goto err_release_devid;
-- 
2.34.1

[PATCH 04/11] iommufd: Add an ioctl IOMMU_IOAS_GET_PA to query PA from IOVA

[Jacob Pan]

To support no-IOMMU mode where userspace drivers perform unsafe DMA
using physical addresses, introduce a new API to retrieve the
physical address of a user-allocated DMA buffer that has been mapped to
an IOVA via IOAS. The mapping is backed by mock I/O page tables maintained
by generic IOMMUPT framework.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 drivers/iommu/iommufd/io_pagetable.c    | 39 +++++++++++++++++++++++++
 drivers/iommu/iommufd/ioas.c            | 22 ++++++++++++++
 drivers/iommu/iommufd/iommufd_private.h |  3 ++
 drivers/iommu/iommufd/main.c            |  3 ++
 include/uapi/linux/iommufd.h            | 25 ++++++++++++++++
 5 files changed, 92 insertions(+)

diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c
index ee003bb2f647..f5ef5b4fb4af 100644
--- a/drivers/iommu/iommufd/io_pagetable.c
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -849,6 +849,45 @@ int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova,
 	return iopt_unmap_iova_range(iopt, iova, iova_last, unmapped);
 }
 
+int iopt_get_phys(struct io_pagetable *iopt, unsigned long iova, u64 *paddr,
+		  u64 *length)
+{
+	struct iopt_area *area;
+	int rc = 0;
+
+	if (!IS_ENABLED(CONFIG_VFIO_NOIOMMU))
+		return -EOPNOTSUPP;
+
+	down_read(&iopt->iova_rwsem);
+	area = iopt_area_iter_first(iopt, iova, iova);
+	if (!area || !area->pages) {
+		rc = -ENOENT;
+		goto unlock_exit;
+	}
+
+	if (!area->storage_domain ||
+	    area->storage_domain->owner != &iommufd_noiommu_ops) {
+		rc = -EOPNOTSUPP;
+		goto unlock_exit;
+	}
+
+	*paddr = iommu_iova_to_phys(area->storage_domain, iova);
+	if (!*paddr) {
+		rc = -EINVAL;
+		goto unlock_exit;
+	}
+	/*
+	 * TBD: we can return contiguous IOVA length so that userspace can
+	 * keep searching for next physical address.
+	 */
+	*length = PAGE_SIZE;
+
+unlock_exit:
+	up_read(&iopt->iova_rwsem);
+
+	return rc;
+}
+
 int iopt_unmap_all(struct io_pagetable *iopt, unsigned long *unmapped)
 {
 	/* If the IOVAs are empty then unmap all succeeds */
diff --git a/drivers/iommu/iommufd/ioas.c b/drivers/iommu/iommufd/ioas.c
index fed06c2b728e..03b394f2fc32 100644
--- a/drivers/iommu/iommufd/ioas.c
+++ b/drivers/iommu/iommufd/ioas.c
@@ -375,6 +375,28 @@ int iommufd_ioas_unmap(struct iommufd_ucmd *ucmd)
 	return rc;
 }
 
+int iommufd_ioas_get_pa(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_ioas_get_pa *cmd = ucmd->cmd;
+	struct iommufd_ioas *ioas;
+	int rc;
+
+	ioas = iommufd_get_ioas(ucmd->ictx, cmd->ioas_id);
+	if (IS_ERR(ioas))
+		return PTR_ERR(ioas);
+
+	rc = iopt_get_phys(&ioas->iopt, cmd->iova, &cmd->out_phys,
+			   &cmd->out_length);
+	if (rc)
+		goto out_put;
+
+	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
+out_put:
+	iommufd_put_object(ucmd->ictx, &ioas->obj);
+
+	return rc;
+}
+
 static void iommufd_release_all_iova_rwsem(struct iommufd_ctx *ictx,
 					   struct xarray *ioas_list)
 {
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 9c18c5eb1899..3302c6a1f99e 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -118,6 +118,8 @@ int iopt_map_pages(struct io_pagetable *iopt, struct list_head *pages_list,
 int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova,
 		    unsigned long length, unsigned long *unmapped);
 int iopt_unmap_all(struct io_pagetable *iopt, unsigned long *unmapped);
+int iopt_get_phys(struct io_pagetable *iopt, unsigned long iova, u64 *paddr,
+		  u64 *length);
 
 int iopt_read_and_clear_dirty_data(struct io_pagetable *iopt,
 				   struct iommu_domain *domain,
@@ -346,6 +348,7 @@ int iommufd_ioas_map_file(struct iommufd_ucmd *ucmd);
 int iommufd_ioas_change_process(struct iommufd_ucmd *ucmd);
 int iommufd_ioas_copy(struct iommufd_ucmd *ucmd);
 int iommufd_ioas_unmap(struct iommufd_ucmd *ucmd);
+int iommufd_ioas_get_pa(struct iommufd_ucmd *ucmd);
 int iommufd_ioas_option(struct iommufd_ucmd *ucmd);
 int iommufd_option_rlimit_mode(struct iommu_option *cmd,
 			       struct iommufd_ctx *ictx);
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 8c6d43601afb..ebae01ed947d 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -432,6 +432,7 @@ union ucmd_buffer {
 	struct iommu_veventq_alloc veventq;
 	struct iommu_vfio_ioas vfio_ioas;
 	struct iommu_viommu_alloc viommu;
+	struct iommu_ioas_get_pa get_pa;
 #ifdef CONFIG_IOMMUFD_TEST
 	struct iommu_test_cmd test;
 #endif
@@ -484,6 +485,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
 		 struct iommu_ioas_map_file, iova),
 	IOCTL_OP(IOMMU_IOAS_UNMAP, iommufd_ioas_unmap, struct iommu_ioas_unmap,
 		 length),
+	IOCTL_OP(IOMMU_IOAS_GET_PA, iommufd_ioas_get_pa, struct iommu_ioas_get_pa,
+		 out_phys),
 	IOCTL_OP(IOMMU_OPTION, iommufd_option, struct iommu_option, val64),
 	IOCTL_OP(IOMMU_VDEVICE_ALLOC, iommufd_vdevice_alloc_ioctl,
 		 struct iommu_vdevice_alloc, virt_id),
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 1dafbc552d37..28c5ce9e5d57 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -57,6 +57,7 @@ enum {
 	IOMMUFD_CMD_IOAS_CHANGE_PROCESS = 0x92,
 	IOMMUFD_CMD_VEVENTQ_ALLOC = 0x93,
 	IOMMUFD_CMD_HW_QUEUE_ALLOC = 0x94,
+	IOMMUFD_CMD_IOAS_GET_PA = 0x95,
 };
 
 /**
@@ -219,6 +220,30 @@ struct iommu_ioas_map {
 };
 #define IOMMU_IOAS_MAP _IO(IOMMUFD_TYPE, IOMMUFD_CMD_IOAS_MAP)
 
+/**
+ * struct iommu_ioas_get_pa - ioctl(IOMMU_IOAS_GET_PA)
+ * @size: sizeof(struct iommu_ioas_get_pa)
+ * @flags: TBD
+ * @ioas_id: IOAS ID to query IOVA to PA mapping from
+ * @__reserved: Must be 0
+ * @iova: IOVA to query
+ * @out_length: Number of bytes contiguous physical address starting from phys
+ * @out_phys: Output physical address the IOVA maps to
+ *
+ * Query the physical address backing an IOVA range. The entire range must be
+ * mapped already. For noiommu devices doing unsafe DMA only.
+ */
+struct iommu_ioas_get_pa {
+	__u32 size;
+	__u32 flags;
+	__u32 ioas_id;
+	__u32 __reserved;
+	__aligned_u64 iova;
+	__aligned_u64 out_length;
+	__aligned_u64 out_phys;
+};
+#define IOMMU_IOAS_GET_PA _IO(IOMMUFD_TYPE, IOMMUFD_CMD_IOAS_GET_PA)
+
 /**
  * struct iommu_ioas_map_file - ioctl(IOMMU_IOAS_MAP_FILE)
  * @size: sizeof(struct iommu_ioas_map_file)
-- 
2.34.1

[PATCH 05/11] vfio: Allow null group for noiommu without containers

[Jacob Pan]

In case of noiommu mode is enabled for VFIO cdev without VFIO container
nor IOMMUFD provided compatibility container, there is no need to
create a dummy group. Update the group operations to tolerate null group
pointer.

Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 drivers/vfio/group.c | 14 ++++++++++++++
 drivers/vfio/vfio.h  | 17 +++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
index 4f15016d2a5f..98f2a4f2ebff 100644
--- a/drivers/vfio/group.c
+++ b/drivers/vfio/group.c
@@ -381,6 +381,9 @@ int vfio_device_block_group(struct vfio_device *device)
 	struct vfio_group *group = device->group;
 	int ret = 0;
 
+	if (vfio_null_group_allowed() && !group)
+		return 0;
+
 	mutex_lock(&group->group_lock);
 	if (group->opened_file) {
 		ret = -EBUSY;
@@ -398,6 +401,9 @@ void vfio_device_unblock_group(struct vfio_device *device)
 {
 	struct vfio_group *group = device->group;
 
+	if (vfio_null_group_allowed() && !group)
+		return;
+
 	mutex_lock(&group->group_lock);
 	group->cdev_device_open_cnt--;
 	mutex_unlock(&group->group_lock);
@@ -589,6 +595,14 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
 	struct vfio_group *group;
 	int ret;
 
+	/*
+	 * With noiommu enabled under cdev interface only, there is no need to
+	 * create a vfio_group if the group based containers are not enabled.
+	 * The cdev interface is exclusively used for iommufd.
+	 */
+	if (vfio_null_group_allowed())
+		return NULL;
+
 	iommu_group = iommu_group_alloc();
 	if (IS_ERR(iommu_group))
 		return ERR_CAST(iommu_group);
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 50128da18bca..838c08077ce2 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -113,6 +113,18 @@ bool vfio_device_has_container(struct vfio_device *device);
 int __init vfio_group_init(void);
 void vfio_group_cleanup(void);
 
+/*
+ * With noiommu enabled and no containers are supported, allow devices that
+ * don't have a dummy group.
+ */
+static inline bool vfio_null_group_allowed(void)
+{
+	if (vfio_noiommu && (!IS_ENABLED(CONFIG_VFIO_CONTAINER) && !IS_ENABLED(CONFIG_IOMMUFD_VFIO_CONTAINER)))
+		return true;
+
+	return false;
+}
+
 static inline bool vfio_device_is_noiommu(struct vfio_device *vdev)
 {
 	return IS_ENABLED(CONFIG_VFIO_NOIOMMU) &&
@@ -189,6 +201,11 @@ static inline void vfio_group_cleanup(void)
 {
 }
 
+static inline bool vfio_null_group_allowed(void)
+{
+	return false;
+}
+
 static inline bool vfio_device_is_noiommu(struct vfio_device *vdev)
 {
 	return false;
-- 
2.34.1

[PATCH 06/11] vfio: Introduce and set noiommu flag on vfio_device

[Jacob Pan]

When a VFIO device is added to a noiommu group, set the noiommu flag on
the vfio_device structure to indicate that the device operates in
noiommu mode.

Also update function signatures to pass vfio_device instead of device,
which has the direct access to the noiommu flag.

Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 drivers/vfio/group.c | 21 +++++++++++----------
 include/linux/vfio.h |  1 +
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
index 98f2a4f2ebff..6f98c57de9e0 100644
--- a/drivers/vfio/group.c
+++ b/drivers/vfio/group.c
@@ -588,7 +588,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group,
 	return ret;
 }
 
-static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
+static struct vfio_group *vfio_noiommu_group_alloc(struct vfio_device *vdev,
 		enum vfio_group_type type)
 {
 	struct iommu_group *iommu_group;
@@ -610,7 +610,7 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
 	ret = iommu_group_set_name(iommu_group, "vfio-noiommu");
 	if (ret)
 		goto out_put_group;
-	ret = iommu_group_add_device(iommu_group, dev);
+	ret = iommu_group_add_device(iommu_group, vdev->dev);
 	if (ret)
 		goto out_put_group;
 
@@ -625,7 +625,7 @@ static struct vfio_group *vfio_noiommu_group_alloc(struct device *dev,
 	return group;
 
 out_remove_device:
-	iommu_group_remove_device(dev);
+	iommu_group_remove_device(vdev->dev);
 out_put_group:
 	iommu_group_put(iommu_group);
 	return ERR_PTR(ret);
@@ -646,23 +646,24 @@ static bool vfio_group_has_device(struct vfio_group *group, struct device *dev)
 	return false;
 }
 
-static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
+static struct vfio_group *vfio_group_find_or_alloc(struct vfio_device *vdev)
 {
 	struct iommu_group *iommu_group;
 	struct vfio_group *group;
 
-	iommu_group = iommu_group_get(dev);
+	iommu_group = iommu_group_get(vdev->dev);
 	if (!iommu_group && vfio_noiommu) {
+		vdev->noiommu = 1;
 		/*
 		 * With noiommu enabled, create an IOMMU group for devices that
 		 * don't already have one, implying no IOMMU hardware/driver
 		 * exists.  Taint the kernel because we're about to give a DMA
 		 * capable device to a user without IOMMU protection.
 		 */
-		group = vfio_noiommu_group_alloc(dev, VFIO_NO_IOMMU);
+		group = vfio_noiommu_group_alloc(vdev, VFIO_NO_IOMMU);
 		if (!IS_ERR(group)) {
 			add_taint(TAINT_USER, LOCKDEP_STILL_OK);
-			dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n");
+			dev_warn(vdev->dev, "Adding kernel taint for vfio-noiommu group on device\n");
 		}
 		return group;
 	}
@@ -673,7 +674,7 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
 	mutex_lock(&vfio.group_lock);
 	group = vfio_group_find_from_iommu(iommu_group);
 	if (group) {
-		if (WARN_ON(vfio_group_has_device(group, dev)))
+		if (WARN_ON(vfio_group_has_device(group, vdev->dev)))
 			group = ERR_PTR(-EINVAL);
 		else
 			refcount_inc(&group->drivers);
@@ -693,9 +694,9 @@ int vfio_device_set_group(struct vfio_device *device,
 	struct vfio_group *group;
 
 	if (type == VFIO_IOMMU)
-		group = vfio_group_find_or_alloc(device->dev);
+		group = vfio_group_find_or_alloc(device);
 	else
-		group = vfio_noiommu_group_alloc(device->dev, type);
+		group = vfio_noiommu_group_alloc(device, type);
 
 	if (IS_ERR(group))
 		return PTR_ERR(group);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index e90859956514..844d14839f96 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -72,6 +72,7 @@ struct vfio_device {
 	u8 iommufd_attached:1;
 #endif
 	u8 cdev_opened:1;
+	u8 noiommu:1;
 #ifdef CONFIG_DEBUG_FS
 	/*
 	 * debug_root is a static property of the vfio_device
-- 
2.34.1

[PATCH 07/11] vfio: Update noiommu device detection logic for cdev

[Jacob Pan]

Rework vfio_device_is_noiommu() to derive noiommu mode based on device,
group type, and configurations.

Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 drivers/vfio/vfio.h | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 838c08077ce2..c5541967ef9b 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -127,8 +127,13 @@ static inline bool vfio_null_group_allowed(void)
 
 static inline bool vfio_device_is_noiommu(struct vfio_device *vdev)
 {
-	return IS_ENABLED(CONFIG_VFIO_NOIOMMU) &&
-	       vdev->group->type == VFIO_NO_IOMMU;
+	if (!IS_ENABLED(CONFIG_VFIO_NOIOMMU))
+		return false;
+
+	if (vfio_null_group_allowed())
+		return vdev->noiommu;
+
+	return vdev->group->type == VFIO_NO_IOMMU;
 }
 #else
 struct vfio_group;
-- 
2.34.1

[PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd

[Jacob Pan]

Now that devices under noiommu mode can bind with IOMMUFD and perform
IOAS operations, lift restrictions on cdev from VFIO side.

No IOMMU cdevs are explicitly named with noiommu prefix. e.g.

    /dev/vfio/
    |-- 7
    |-- devices
    |   `-- noiommu-vfio0
    `-- vfio

Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 drivers/vfio/Kconfig     |  6 ++++--
 drivers/vfio/iommufd.c   |  7 -------
 drivers/vfio/vfio.h      |  8 +-------
 drivers/vfio/vfio_main.c | 22 +++++++++++++++++++---
 include/linux/vfio.h     |  9 +++++++++
 5 files changed, 33 insertions(+), 19 deletions(-)

diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index ceae52fd7586..1f3fd7140604 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -22,8 +22,7 @@ config VFIO_DEVICE_CDEV
 	  The VFIO device cdev is another way for userspace to get device
 	  access. Userspace gets device fd by opening device cdev under
 	  /dev/vfio/devices/vfioX, and then bind the device fd with an iommufd
-	  to set up secure DMA context for device access.  This interface does
-	  not support noiommu.
+	  to set up secure DMA context for device access.
 
 	  If you don't know what to do here, say N.
 
@@ -63,6 +62,9 @@ endif
 config VFIO_NOIOMMU
 	bool "VFIO No-IOMMU support"
 	depends on VFIO_GROUP
+	select GENERIC_PT
+	select IOMMU_PT
+	select IOMMU_PT_AMDV1
 	help
 	  VFIO is built on the ability to isolate devices using the IOMMU.
 	  Only with an IOMMU can userspace access to DMA capable devices be
diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
index a38d262c6028..26c9c3068c77 100644
--- a/drivers/vfio/iommufd.c
+++ b/drivers/vfio/iommufd.c
@@ -25,10 +25,6 @@ int vfio_df_iommufd_bind(struct vfio_device_file *df)
 
 	lockdep_assert_held(&vdev->dev_set->lock);
 
-	/* Returns 0 to permit device opening under noiommu mode */
-	if (vfio_device_is_noiommu(vdev))
-		return 0;
-
 	return vdev->ops->bind_iommufd(vdev, ictx, &df->devid);
 }
 
@@ -58,9 +54,6 @@ void vfio_df_iommufd_unbind(struct vfio_device_file *df)
 
 	lockdep_assert_held(&vdev->dev_set->lock);
 
-	if (vfio_device_is_noiommu(vdev))
-		return;
-
 	if (vdev->ops->unbind_iommufd)
 		vdev->ops->unbind_iommufd(vdev);
 }
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index c5541967ef9b..f6262f2cc7a6 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -381,19 +381,13 @@ void vfio_init_device_cdev(struct vfio_device *device);
 
 static inline int vfio_device_add(struct vfio_device *device)
 {
-	/* cdev does not support noiommu device */
-	if (vfio_device_is_noiommu(device))
-		return device_add(&device->device);
 	vfio_init_device_cdev(device);
 	return cdev_device_add(&device->cdev, &device->device);
 }
 
 static inline void vfio_device_del(struct vfio_device *device)
 {
-	if (vfio_device_is_noiommu(device))
-		device_del(&device->device);
-	else
-		cdev_device_del(&device->cdev, &device->device);
+	cdev_device_del(&device->cdev, &device->device);
 }
 
 int vfio_device_fops_cdev_open(struct inode *inode, struct file *filep);
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 742477546b15..099d9b1ade4c 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -331,13 +331,15 @@ static int __vfio_register_dev(struct vfio_device *device,
 	if (!device->dev_set)
 		vfio_assign_device_set(device, device);
 
-	ret = dev_set_name(&device->device, "vfio%d", device->index);
+	ret = vfio_device_set_group(device, type);
 	if (ret)
 		return ret;
 
-	ret = vfio_device_set_group(device, type);
+	/* Just to be safe, expose to user explicitly noiommu cdev node */
+	ret = dev_set_name(&device->device, "%svfio%d",
+					   device->noiommu ? "noiommu-" : "", device->index);
 	if (ret)
-		return ret;
+		goto err_out;
 
 	/*
 	 * VFIO always sets IOMMU_CACHE because we offer no way for userspace to
@@ -357,6 +359,10 @@ static int __vfio_register_dev(struct vfio_device *device,
 	/* Refcounting can't start until the driver calls register */
 	refcount_set(&device->refcount, 1);
 
+	/* noiommu device w/o container may have NULL group */
+	if (vfio_device_is_noiommu(device) && !vfio_device_has_group(device))
+		return 0;
+
 	vfio_device_group_register(device);
 	vfio_device_debugfs_init(device);
 
@@ -391,6 +397,16 @@ void vfio_unregister_group_dev(struct vfio_device *device)
 	bool interrupted = false;
 	long rc;
 
+	/*
+	 * For noiommu devices without a container, thus no dummy group,
+	 * simply delete and unregister to balance refcount.
+	 */
+	if (device->noiommu && !vfio_device_has_group(device)) {
+		vfio_device_del(device);
+		vfio_device_put_registration(device);
+		return;
+	}
+
 	/*
 	 * Prevent new device opened by userspace via the
 	 * VFIO_GROUP_GET_DEVICE_FD in the group path.
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 844d14839f96..775bd4f6bae9 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -327,6 +327,10 @@ struct iommu_group *vfio_file_iommu_group(struct file *file);
 #if IS_ENABLED(CONFIG_VFIO_GROUP)
 bool vfio_file_is_group(struct file *file);
 bool vfio_file_has_dev(struct file *file, struct vfio_device *device);
+static inline bool vfio_device_has_group(struct vfio_device *device)
+{
+	return device->group;
+}
 #else
 static inline bool vfio_file_is_group(struct file *file)
 {
@@ -337,6 +341,11 @@ static inline bool vfio_file_has_dev(struct file *file, struct vfio_device *devi
 {
 	return false;
 }
+
+static inline bool vfio_device_has_group(struct vfio_device *device)
+{
+	return false;
+}
 #endif
 bool vfio_file_is_valid(struct file *file);
 bool vfio_file_enforced_coherent(struct file *file);
-- 
2.34.1

Re: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd

[kernel test robot]

Hi Jacob,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v7.0-rc1 next-20260227]
[cannot apply to awilliam-vfio/next awilliam-vfio/for-linus]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jacob-Pan/iommufd-Support-a-HWPT-without-an-iommu-driver-for-noiommu/20260228-020145
base:   linus/master
patch link:    https://lore.kernel.org/r/20260227175247.26103-9-jacob.pan%40linux.microsoft.com
patch subject: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd
config: sh-randconfig-001-20260228 (https://download.01.org/0day-ci/archive/20260228/202602280557.4SdsBbeJ-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 15.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260228/202602280557.4SdsBbeJ-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202602280557.4SdsBbeJ-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

   In file included from drivers/iommu/generic_pt/fmt/iommu_template.h:36,
                    from drivers/iommu/generic_pt/fmt/iommu_amdv1.c:15:
   drivers/iommu/generic_pt/fmt/amdv1.h: In function 'amdv1pt_install_table':
>> drivers/iommu/generic_pt/fmt/amdv1.h:255:16: error: implicit declaration of function 'pt_table_install64'; did you mean 'pt_table_install32'? [-Wimplicit-function-declaration]
     255 |         return pt_table_install64(pts, entry);
         |                ^~~~~~~~~~~~~~~~~~
         |                pt_table_install32
   In file included from include/linux/atomic.h:80,
                    from drivers/iommu/generic_pt/fmt/../pt_defs.h:17,
                    from drivers/iommu/generic_pt/fmt/iommu_template.h:35:
   drivers/iommu/generic_pt/fmt/amdv1.h: In function 'amdv1pt_entry_make_write_dirty':
>> include/linux/atomic/atomic-arch-fallback.h:259:14: error: invalid use of void expression
     259 |         ___r = raw_cmpxchg64((_ptr), ___o, (_new)); \
         |              ^
   include/linux/atomic/atomic-instrumented.h:4918:9: note: in expansion of macro 'raw_try_cmpxchg64'
    4918 |         raw_try_cmpxchg64(__ai_ptr, __ai_oldp, __VA_ARGS__); \
         |         ^~~~~~~~~~~~~~~~~
   drivers/iommu/generic_pt/fmt/amdv1.h:318:16: note: in expansion of macro 'try_cmpxchg64'
     318 |         return try_cmpxchg64(tablep, &pts->entry, new);
         |                ^~~~~~~~~~~~~
>> drivers/iommu/generic_pt/fmt/amdv1.h:316:13: warning: unused variable 'new' [-Wunused-variable]
     316 |         u64 new = pts->entry | AMDV1PT_FMT_D;
         |             ^~~
--
   In file included from generic_pt/fmt/iommu_template.h:36,
                    from generic_pt/fmt/iommu_amdv1.c:15:
   generic_pt/fmt/amdv1.h: In function 'amdv1pt_install_table':
   generic_pt/fmt/amdv1.h:255:16: error: implicit declaration of function 'pt_table_install64'; did you mean 'pt_table_install32'? [-Wimplicit-function-declaration]
     255 |         return pt_table_install64(pts, entry);
         |                ^~~~~~~~~~~~~~~~~~
         |                pt_table_install32
   In file included from include/linux/atomic.h:80,
                    from generic_pt/fmt/../pt_defs.h:17,
                    from generic_pt/fmt/iommu_template.h:35:
   generic_pt/fmt/amdv1.h: In function 'amdv1pt_entry_make_write_dirty':
>> include/linux/atomic/atomic-arch-fallback.h:259:14: error: invalid use of void expression
     259 |         ___r = raw_cmpxchg64((_ptr), ___o, (_new)); \
         |              ^
   include/linux/atomic/atomic-instrumented.h:4918:9: note: in expansion of macro 'raw_try_cmpxchg64'
    4918 |         raw_try_cmpxchg64(__ai_ptr, __ai_oldp, __VA_ARGS__); \
         |         ^~~~~~~~~~~~~~~~~
   generic_pt/fmt/amdv1.h:318:16: note: in expansion of macro 'try_cmpxchg64'
     318 |         return try_cmpxchg64(tablep, &pts->entry, new);
         |                ^~~~~~~~~~~~~
   generic_pt/fmt/amdv1.h:316:13: warning: unused variable 'new' [-Wunused-variable]
     316 |         u64 new = pts->entry | AMDV1PT_FMT_D;
         |             ^~~

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for IOMMU_PT
   Depends on [n]: IOMMU_SUPPORT [=n] && GENERIC_PT [=y]
   Selected by [y]:
   - VFIO_NOIOMMU [=y] && VFIO [=y] && VFIO_GROUP [=y]
   WARNING: unmet direct dependencies detected for IOMMU_PT_AMDV1
   Depends on [n]: GENERIC_PT [=y] && IOMMU_PT [=y] && !GENERIC_ATOMIC64 [=y]
   Selected by [y]:
   - VFIO_NOIOMMU [=y] && VFIO [=y] && VFIO_GROUP [=y]


vim +255 drivers/iommu/generic_pt/fmt/amdv1.h

879ced2bab1ba9 Jason Gunthorpe 2025-11-04  236  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  237  static inline bool amdv1pt_install_table(struct pt_state *pts,
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  238  					 pt_oaddr_t table_pa,
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  239  					 const struct pt_write_attrs *attrs)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  240  {
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  241  	u64 entry;
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  242  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  243  	/*
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  244  	 * IR and IW are ANDed from the table levels along with the PTE. We
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  245  	 * always control permissions from the PTE, so always set IR and IW for
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  246  	 * tables.
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  247  	 */
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  248  	entry = AMDV1PT_FMT_PR |
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  249  		FIELD_PREP(AMDV1PT_FMT_NEXT_LEVEL, pts->level) |
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  250  		FIELD_PREP(AMDV1PT_FMT_OA,
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  251  			   log2_div(table_pa, PT_GRANULE_LG2SZ)) |
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  252  		AMDV1PT_FMT_IR | AMDV1PT_FMT_IW;
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  253  	if (pts_feature(pts, PT_FEAT_AMDV1_ENCRYPT_TABLES))
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  254  		entry = __sme_set(entry);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04 @255  	return pt_table_install64(pts, entry);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  256  }
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  257  #define pt_install_table amdv1pt_install_table
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  258  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  259  static inline void amdv1pt_attr_from_entry(const struct pt_state *pts,
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  260  					   struct pt_write_attrs *attrs)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  261  {
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  262  	attrs->descriptor_bits =
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  263  		pts->entry & (AMDV1PT_FMT_FC | AMDV1PT_FMT_IR | AMDV1PT_FMT_IW);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  264  }
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  265  #define pt_attr_from_entry amdv1pt_attr_from_entry
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  266  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  267  static inline void amdv1pt_clear_entries(struct pt_state *pts,
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  268  					 unsigned int num_contig_lg2)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  269  {
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  270  	u64 *tablep = pt_cur_table(pts, u64) + pts->index;
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  271  	u64 *end = tablep + log2_to_int(num_contig_lg2);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  272  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  273  	/*
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  274  	 * gcc generates rep stos for the io-pgtable code, and this difference
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  275  	 * can show in microbenchmarks with larger contiguous page sizes.
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  276  	 * rep is slower for small cases.
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  277  	 */
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  278  	if (num_contig_lg2 <= ilog2(32)) {
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  279  		for (; tablep != end; tablep++)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  280  			WRITE_ONCE(*tablep, 0);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  281  	} else {
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  282  		memset64(tablep, 0, log2_to_int(num_contig_lg2));
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  283  	}
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  284  }
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  285  #define pt_clear_entries amdv1pt_clear_entries
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  286  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  287  static inline bool amdv1pt_entry_is_write_dirty(const struct pt_state *pts)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  288  {
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  289  	unsigned int num_contig_lg2 = amdv1pt_entry_num_contig_lg2(pts);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  290  	u64 *tablep = pt_cur_table(pts, u64) +
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  291  		      log2_set_mod(pts->index, 0, num_contig_lg2);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  292  	u64 *end = tablep + log2_to_int(num_contig_lg2);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  293  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  294  	for (; tablep != end; tablep++)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  295  		if (READ_ONCE(*tablep) & AMDV1PT_FMT_D)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  296  			return true;
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  297  	return false;
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  298  }
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  299  #define pt_entry_is_write_dirty amdv1pt_entry_is_write_dirty
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  300  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  301  static inline void amdv1pt_entry_make_write_clean(struct pt_state *pts)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  302  {
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  303  	unsigned int num_contig_lg2 = amdv1pt_entry_num_contig_lg2(pts);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  304  	u64 *tablep = pt_cur_table(pts, u64) +
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  305  		      log2_set_mod(pts->index, 0, num_contig_lg2);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  306  	u64 *end = tablep + log2_to_int(num_contig_lg2);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  307  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  308  	for (; tablep != end; tablep++)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  309  		WRITE_ONCE(*tablep, READ_ONCE(*tablep) & ~(u64)AMDV1PT_FMT_D);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  310  }
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  311  #define pt_entry_make_write_clean amdv1pt_entry_make_write_clean
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  312  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  313  static inline bool amdv1pt_entry_make_write_dirty(struct pt_state *pts)
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  314  {
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  315  	u64 *tablep = pt_cur_table(pts, u64) + pts->index;
879ced2bab1ba9 Jason Gunthorpe 2025-11-04 @316  	u64 new = pts->entry | AMDV1PT_FMT_D;
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  317  
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  318  	return try_cmpxchg64(tablep, &pts->entry, new);
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  319  }
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  320  #define pt_entry_make_write_dirty amdv1pt_entry_make_write_dirty
879ced2bab1ba9 Jason Gunthorpe 2025-11-04  321  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd

[kernel test robot]

Hi Jacob,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v7.0-rc1 next-20260227]
[cannot apply to awilliam-vfio/next awilliam-vfio/for-linus]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jacob-Pan/iommufd-Support-a-HWPT-without-an-iommu-driver-for-noiommu/20260228-020145
base:   linus/master
patch link:    https://lore.kernel.org/r/20260227175247.26103-9-jacob.pan%40linux.microsoft.com
patch subject: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd
config: riscv-randconfig-r134-20260228 (https://download.01.org/0day-ci/archive/20260228/202602280855.WxyIHCy5-lkp@intel.com/config)
compiler: riscv32-linux-gcc (GCC) 8.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260228/202602280855.WxyIHCy5-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202602280855.WxyIHCy5-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from drivers/iommu/generic_pt/fmt/iommu_template.h:36,
                    from drivers/iommu/generic_pt/fmt/iommu_amdv1.c:15:
   drivers/iommu/generic_pt/fmt/amdv1.h: In function 'amdv1pt_install_table':
   drivers/iommu/generic_pt/fmt/amdv1.h:255:9: error: implicit declaration of function 'pt_table_install64'; did you mean 'pt_table_install32'? [-Werror=implicit-function-declaration]
     return pt_table_install64(pts, entry);
            ^~~~~~~~~~~~~~~~~~
            pt_table_install32
   In file included from include/linux/generic_pt/common.h:10,
                    from drivers/iommu/generic_pt/fmt/iommu_template.h:33,
                    from drivers/iommu/generic_pt/fmt/iommu_amdv1.c:15:
   drivers/iommu/generic_pt/fmt/amdv1.h: In function 'amdv1pt_entry_make_write_dirty':
>> include/linux/bits.h:49:20: warning: right shift count >= width of type [-Wshift-count-overflow]
           type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h)))))
                       ^~
   include/linux/bits.h:51:24: note: in expansion of macro 'GENMASK_TYPE'
    #define GENMASK(h, l)  GENMASK_TYPE(unsigned long, h, l)
                           ^~~~~~~~~~~~
   arch/riscv/include/asm/cmpxchg.h:152:18: note: in expansion of macro 'GENMASK'
      ulong __mask = GENMASK(((sizeof(*p)) * BITS_PER_BYTE) - 1, 0) \
                     ^~~~~~~
   arch/riscv/include/asm/cmpxchg.h:224:3: note: in expansion of macro '__arch_cmpxchg_masked'
      __arch_cmpxchg_masked(sc_sfx, ".b" cas_sfx,  \
      ^~~~~~~~~~~~~~~~~~~~~
   arch/riscv/include/asm/cmpxchg.h:283:2: note: in expansion of macro '_arch_cmpxchg'
     _arch_cmpxchg((ptr), (o), (n),     \
     ^~~~~~~~~~~~~
   arch/riscv/include/asm/cmpxchg.h:294:2: note: in expansion of macro 'arch_cmpxchg'
     arch_cmpxchg((ptr), (o), (n));     \
     ^~~~~~~~~~~~
   include/linux/atomic/atomic-arch-fallback.h:98:23: note: in expansion of macro 'arch_cmpxchg64'
    #define raw_cmpxchg64 arch_cmpxchg64
                          ^~~~~~~~~~~~~~
   include/linux/atomic/atomic-arch-fallback.h:259:9: note: in expansion of macro 'raw_cmpxchg64'
     ___r = raw_cmpxchg64((_ptr), ___o, (_new)); \
            ^~~~~~~~~~~~~
   include/linux/atomic/atomic-instrumented.h:4918:2: note: in expansion of macro 'raw_try_cmpxchg64'
     raw_try_cmpxchg64(__ai_ptr, __ai_oldp, __VA_ARGS__); \
     ^~~~~~~~~~~~~~~~~
   drivers/iommu/generic_pt/fmt/amdv1.h:318:9: note: in expansion of macro 'try_cmpxchg64'
     return try_cmpxchg64(tablep, &pts->entry, new);
            ^~~~~~~~~~~~~
>> include/linux/bits.h:49:20: warning: right shift count >= width of type [-Wshift-count-overflow]
           type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h)))))
                       ^~
   include/linux/bits.h:51:24: note: in expansion of macro 'GENMASK_TYPE'
    #define GENMASK(h, l)  GENMASK_TYPE(unsigned long, h, l)
                           ^~~~~~~~~~~~
   arch/riscv/include/asm/cmpxchg.h:152:18: note: in expansion of macro 'GENMASK'
      ulong __mask = GENMASK(((sizeof(*p)) * BITS_PER_BYTE) - 1, 0) \
                     ^~~~~~~
   arch/riscv/include/asm/cmpxchg.h:230:3: note: in expansion of macro '__arch_cmpxchg_masked'
      __arch_cmpxchg_masked(sc_sfx, ".h" cas_sfx,  \
      ^~~~~~~~~~~~~~~~~~~~~
   arch/riscv/include/asm/cmpxchg.h:283:2: note: in expansion of macro '_arch_cmpxchg'
     _arch_cmpxchg((ptr), (o), (n),     \
     ^~~~~~~~~~~~~
   arch/riscv/include/asm/cmpxchg.h:294:2: note: in expansion of macro 'arch_cmpxchg'
     arch_cmpxchg((ptr), (o), (n));     \
     ^~~~~~~~~~~~
   include/linux/atomic/atomic-arch-fallback.h:98:23: note: in expansion of macro 'arch_cmpxchg64'
    #define raw_cmpxchg64 arch_cmpxchg64
                          ^~~~~~~~~~~~~~
   include/linux/atomic/atomic-arch-fallback.h:259:9: note: in expansion of macro 'raw_cmpxchg64'
     ___r = raw_cmpxchg64((_ptr), ___o, (_new)); \
            ^~~~~~~~~~~~~
   include/linux/atomic/atomic-instrumented.h:4918:2: note: in expansion of macro 'raw_try_cmpxchg64'
     raw_try_cmpxchg64(__ai_ptr, __ai_oldp, __VA_ARGS__); \
     ^~~~~~~~~~~~~~~~~
   drivers/iommu/generic_pt/fmt/amdv1.h:318:9: note: in expansion of macro 'try_cmpxchg64'
     return try_cmpxchg64(tablep, &pts->entry, new);
            ^~~~~~~~~~~~~
   cc1: some warnings being treated as errors

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for IOMMU_PT_AMDV1
   Depends on [n]: GENERIC_PT [=y] && IOMMU_PT [=y] && !GENERIC_ATOMIC64 [=y]
   Selected by [y]:
   - VFIO_NOIOMMU [=y] && VFIO [=y] && VFIO_GROUP [=y]


vim +49 include/linux/bits.h

31299a5e021124 Vincent Mailhol 2025-03-26  35  
19408200c09485 Vincent Mailhol 2025-03-26  36  /*
19408200c09485 Vincent Mailhol 2025-03-26  37   * Generate a mask for the specified type @t. Additional checks are made to
19408200c09485 Vincent Mailhol 2025-03-26  38   * guarantee the value returned fits in that type, relying on
19408200c09485 Vincent Mailhol 2025-03-26  39   * -Wshift-count-overflow compiler check to detect incompatible arguments.
19408200c09485 Vincent Mailhol 2025-03-26  40   * For example, all these create build errors or warnings:
19408200c09485 Vincent Mailhol 2025-03-26  41   *
19408200c09485 Vincent Mailhol 2025-03-26  42   * - GENMASK(15, 20): wrong argument order
19408200c09485 Vincent Mailhol 2025-03-26  43   * - GENMASK(72, 15): doesn't fit unsigned long
19408200c09485 Vincent Mailhol 2025-03-26  44   * - GENMASK_U32(33, 15): doesn't fit in a u32
19408200c09485 Vincent Mailhol 2025-03-26  45   */
19408200c09485 Vincent Mailhol 2025-03-26  46  #define GENMASK_TYPE(t, h, l)					\
19408200c09485 Vincent Mailhol 2025-03-26  47  	((t)(GENMASK_INPUT_CHECK(h, l) +			\
19408200c09485 Vincent Mailhol 2025-03-26  48  	     (type_max(t) << (l) &				\
19408200c09485 Vincent Mailhol 2025-03-26 @49  	      type_max(t) >> (BITS_PER_TYPE(t) - 1 - (h)))))
19408200c09485 Vincent Mailhol 2025-03-26  50  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd

[Jason Gunthorpe]

On Sat, Feb 28, 2026 at 08:18:41AM +0800, kernel test robot wrote:
> Kconfig warnings: (for reference only)
>    WARNING: unmet direct dependencies detected for IOMMU_PT_AMDV1
>    Depends on [n]: GENERIC_PT [=y] && IOMMU_PT [=y] && !GENERIC_ATOMIC64 [=y]
>    Selected by [y]:
>    - VFIO_NOIOMMU [=y] && VFIO [=y] && VFIO_GROUP [=y]

Some kconfig stuff is missing, the iommufd IOMMU would only work with
GENERIC_ATOMIC64

Jason

Re: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd

[Jacob Pan]

Hi Jason,

On Fri, 27 Feb 2026 20:35:40 -0400
Jason Gunthorpe <jgg@nvidia.com> wrote:

> On Sat, Feb 28, 2026 at 08:18:41AM +0800, kernel test robot wrote:
> > Kconfig warnings: (for reference only)
> >    WARNING: unmet direct dependencies detected for IOMMU_PT_AMDV1
> >    Depends on [n]: GENERIC_PT [=y] && IOMMU_PT [=y] &&
> > !GENERIC_ATOMIC64 [=y] Selected by [y]:
> >    - VFIO_NOIOMMU [=y] && VFIO [=y] && VFIO_GROUP [=y]  
> 
> Some kconfig stuff is missing, the iommufd IOMMU would only work with
> GENERIC_ATOMIC64
I don't quite understand this dependency on GENERIC_ATOMIC64, or you
mean the opposite? since we currently have:
config IOMMU_PT_AMDV1
	tristate "IOMMU page table for 64-bit AMD IOMMU v1"
	depends on !GENERIC_ATOMIC64 # for cmpxchg64

And I already have noiommu depends on AMDV1 for mock page tables.

Anyway, this particular build issue can be fixed by adding
IOMMU_SUPPORT. i.e.

diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index 1f3fd7140604..78feca3d0c8b 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -65,6 +65,7 @@ config VFIO_NOIOMMU
        select GENERIC_PT
        select IOMMU_PT
        select IOMMU_PT_AMDV1
+       depends on IOMMU_SUPPORT
        help

Re: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd

[Jason Gunthorpe]

On Thu, Mar 05, 2026 at 03:26:14PM -0800, Jacob Pan wrote:
> Hi Jason,
> 
> On Fri, 27 Feb 2026 20:35:40 -0400
> Jason Gunthorpe <jgg@nvidia.com> wrote:
> 
> > On Sat, Feb 28, 2026 at 08:18:41AM +0800, kernel test robot wrote:
> > > Kconfig warnings: (for reference only)
> > >    WARNING: unmet direct dependencies detected for IOMMU_PT_AMDV1
> > >    Depends on [n]: GENERIC_PT [=y] && IOMMU_PT [=y] &&
> > > !GENERIC_ATOMIC64 [=y] Selected by [y]:
> > >    - VFIO_NOIOMMU [=y] && VFIO [=y] && VFIO_GROUP [=y]  
> > 
> > Some kconfig stuff is missing, the iommufd IOMMU would only work with
> > GENERIC_ATOMIC64
> I don't quite understand this dependency on GENERIC_ATOMIC64, or you
> mean the opposite? since we currently have:

Oh, right the inverse.

> config IOMMU_PT_AMDV1
> 	tristate "IOMMU page table for 64-bit AMD IOMMU v1"
> 	depends on !GENERIC_ATOMIC64 # for cmpxchg64
> 
> And I already have noiommu depends on AMDV1 for mock page tables.

I think it is kconfig not being really transitive with select
dependencies. So things like !GENERIC_ATOMIC64 have to be in the
parent that uses select too.

You could also possibly use depends to avoid this, IIRC.

> Anyway, this particular build issue can be fixed by adding
> IOMMU_SUPPORT. i.e.

That feels indirect, but maybe it is needed too..

Jason

Re: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd

[Jacob Pan]

Hi Jason,

On Thu, 5 Mar 2026 19:38:27 -0400
Jason Gunthorpe <jgg@nvidia.com> wrote:

> On Thu, Mar 05, 2026 at 03:26:14PM -0800, Jacob Pan wrote:
> > Hi Jason,
> > 
> > On Fri, 27 Feb 2026 20:35:40 -0400
> > Jason Gunthorpe <jgg@nvidia.com> wrote:
> >   
> > > On Sat, Feb 28, 2026 at 08:18:41AM +0800, kernel test robot
> > > wrote:  
> > > > Kconfig warnings: (for reference only)
> > > >    WARNING: unmet direct dependencies detected for
> > > > IOMMU_PT_AMDV1 Depends on [n]: GENERIC_PT [=y] && IOMMU_PT [=y]
> > > > && !GENERIC_ATOMIC64 [=y] Selected by [y]:
> > > >    - VFIO_NOIOMMU [=y] && VFIO [=y] && VFIO_GROUP [=y]    
> > > 
> > > Some kconfig stuff is missing, the iommufd IOMMU would only work
> > > with GENERIC_ATOMIC64  
> > I don't quite understand this dependency on GENERIC_ATOMIC64, or you
> > mean the opposite? since we currently have:  
> 
> Oh, right the inverse.
> 
> > config IOMMU_PT_AMDV1
> > 	tristate "IOMMU page table for 64-bit AMD IOMMU v1"
> > 	depends on !GENERIC_ATOMIC64 # for cmpxchg64
> > 
> > And I already have noiommu depends on AMDV1 for mock page tables.  
> 
> I think it is kconfig not being really transitive with select
> dependencies. So things like !GENERIC_ATOMIC64 have to be in the
> parent that uses select too.
> 
> You could also possibly use depends to avoid this, IIRC.
I have tried to use "depends on" instead of select but it made
VFIO_NOIOMMU impossible to enable if COMPILE_TEST is not set. I think
it is because:
menuconfig GENERIC_PT                                  
        bool "Generic Radix Page Table" if COMPILE_TEST

> > Anyway, this particular build issue can be fixed by adding
> > IOMMU_SUPPORT. i.e.  
> 
> That feels indirect, but maybe it is needed too..
Yeah, it does feel a bit counterintuitive that noiommu depends on IOMMU
support, but as noiommu mode is made to behave increasingly like full
IOMMU support, this may be unavoidable.

I just sent out v2.

Thanks,

Jacob

Re: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd

[kernel test robot]

Hi Jacob,

kernel test robot noticed the following build errors:

[auto build test ERROR on linus/master]
[also build test ERROR on v7.0-rc1 next-20260227]
[cannot apply to awilliam-vfio/next awilliam-vfio/for-linus]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Jacob-Pan/iommufd-Support-a-HWPT-without-an-iommu-driver-for-noiommu/20260228-020145
base:   linus/master
patch link:    https://lore.kernel.org/r/20260227175247.26103-9-jacob.pan%40linux.microsoft.com
patch subject: [PATCH 08/11] vfio: Enable cdev noiommu mode under iommufd
config: i386-buildonly-randconfig-001-20260228 (https://download.01.org/0day-ci/archive/20260228/202602280846.BaUZcBnS-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260228/202602280846.BaUZcBnS-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202602280846.BaUZcBnS-lkp@intel.com/

All errors (new ones prefixed by >>):

>> ld.lld: error: undefined symbol: iommu_put_pages_list
   >>> referenced by iommu_pt.h:768 (drivers/iommu/generic_pt/fmt/../iommu_pt.h:768)
   >>>               drivers/iommu/generic_pt/fmt/iommu_amdv1.o:(pt_iommu_amdv1_map_pages) in archive vmlinux.a
   >>> referenced by iommu_pt.h:768 (drivers/iommu/generic_pt/fmt/../iommu_pt.h:768)
   >>>               drivers/iommu/generic_pt/fmt/iommu_amdv1.o:(pt_iommu_amdv1_map_pages) in archive vmlinux.a
   >>> referenced by iommu_pt.h:768 (drivers/iommu/generic_pt/fmt/../iommu_pt.h:768)
   >>>               drivers/iommu/generic_pt/fmt/iommu_amdv1.o:(pt_iommu_amdv1_map_pages) in archive vmlinux.a
   >>> referenced 1 more times

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for IOMMU_PT
   Depends on [n]: IOMMU_SUPPORT [=n] && GENERIC_PT [=y]
   Selected by [y]:
   - VFIO_NOIOMMU [=y] && VFIO [=y] && VFIO_GROUP [=y]

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

[PATCH 09/11] vfio:selftest: Handle VFIO noiommu cdev

[Jacob Pan]

With unsafe DMA noiommu mode, the vfio devices are prefixed with
noiommu-, e.g.
/dev/vfio/
|-- devices
|   `-- noiommu-vfio0
|-- noiommu-0
`-- vfio
Let vfio tests, such as luo kexec test, accommodate the noiommu device
files.

Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 .../selftests/vfio/lib/vfio_pci_device.c      | 25 +++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
index 4e5871f1ebc3..15ddeb634a8d 100644
--- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
+++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
@@ -290,6 +290,24 @@ static void vfio_pci_device_setup(struct vfio_pci_device *device)
 		device->msi_eventfds[i] = -1;
 }
 
+
+static int is_unsafe_noiommu_mode_enabled(void)
+{
+	const char *path = "/sys/module/vfio/parameters/enable_unsafe_noiommu_mode";
+	FILE *f;
+	int c;
+
+	f = fopen(path, "re");
+	if (!f)
+		return 0;
+
+	c = fgetc(f);
+	fclose(f);
+	if (c == 'Y' || c == 'y')
+		return 1;
+	return 0;
+}
+
 const char *vfio_pci_get_cdev_path(const char *bdf)
 {
 	char dir_path[PATH_MAX];
@@ -306,8 +324,11 @@ const char *vfio_pci_get_cdev_path(const char *bdf)
 	VFIO_ASSERT_NOT_NULL(dir, "Failed to open directory %s\n", dir_path);
 
 	while ((entry = readdir(dir)) != NULL) {
-		/* Find the file that starts with "vfio" */
-		if (strncmp("vfio", entry->d_name, 4))
+		/* Find the file that starts with "noiommu-vfio" or "vfio" */
+		if (is_unsafe_noiommu_mode_enabled()) {
+			if (strncmp("noiommu-vfio", entry->d_name, strlen("noiommu-vfio")))
+				continue;
+		} else if (strncmp("vfio", entry->d_name, 4))
 			continue;
 
 		snprintf(cdev_path, PATH_MAX, "/dev/vfio/devices/%s", entry->d_name);
-- 
2.34.1

[PATCH 10/11] selftests/vfio: Add iommufd noiommu mode selftest for cdev

[Jacob Pan]

Add comprehensive selftest for VFIO device operations with iommufd in
noiommu mode. Tests cover:
- Device binding to iommufd
- IOAS (I/O Address Space) allocation, mapping with dummy IOVA
- Retrieve PA from dummy IOVA
- Device attach/detach operations as usual

Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 tools/testing/selftests/vfio/Makefile         |   1 +
 .../vfio/vfio_iommufd_noiommu_test.c          | 540 ++++++++++++++++++
 2 files changed, 541 insertions(+)
 create mode 100644 tools/testing/selftests/vfio/vfio_iommufd_noiommu_test.c

diff --git a/tools/testing/selftests/vfio/Makefile b/tools/testing/selftests/vfio/Makefile
index 8e90e409e91d..90f41d8ce3c7 100644
--- a/tools/testing/selftests/vfio/Makefile
+++ b/tools/testing/selftests/vfio/Makefile
@@ -9,6 +9,7 @@ CFLAGS = $(KHDR_INCLUDES)
 TEST_GEN_PROGS += vfio_dma_mapping_test
 TEST_GEN_PROGS += vfio_dma_mapping_mmio_test
 TEST_GEN_PROGS += vfio_iommufd_setup_test
+TEST_GEN_PROGS += vfio_iommufd_noiommu_test
 TEST_GEN_PROGS += vfio_pci_device_test
 TEST_GEN_PROGS += vfio_pci_device_init_perf_test
 TEST_GEN_PROGS += vfio_pci_driver_test
diff --git a/tools/testing/selftests/vfio/vfio_iommufd_noiommu_test.c b/tools/testing/selftests/vfio/vfio_iommufd_noiommu_test.c
new file mode 100644
index 000000000000..a2469afee39a
--- /dev/null
+++ b/tools/testing/selftests/vfio/vfio_iommufd_noiommu_test.c
@@ -0,0 +1,540 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * VFIO iommufd NoIOMMU Mode Selftest
+ *
+ * Tests VFIO device operations with iommufd in noiommu mode, including:
+ * - Device binding to iommufd
+ * - IOAS (I/O Address Space) allocation and management
+ * - Device attach/detach to IOAS
+ * - Memory mapping in IOAS
+ * - Device info queries and reset
+ */
+
+#include <linux/limits.h>
+#include <linux/vfio.h>
+#include <linux/iommufd.h>
+
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <dirent.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <errno.h>
+
+#include <libvfio.h>
+#include "kselftest_harness.h"
+
+static const char iommu_dev_path[] = "/dev/iommu";
+static const char *cdev_path;
+
+static char *vfio_noiommu_get_device_id(const char *bdf)
+{
+	char *path = NULL;
+	char *vfio_id = NULL;
+	struct dirent *dentry;
+	DIR *dp;
+
+	if (asprintf(&path, "/sys/bus/pci/devices/%s/vfio-dev", bdf) < 0)
+		return NULL;
+
+	dp = opendir(path);
+	if (!dp) {
+		free(path);
+		return NULL;
+	}
+
+	while ((dentry = readdir(dp)) != NULL) {
+		if (strncmp("noiommu-vfio", dentry->d_name, 12) == 0) {
+			vfio_id = strdup(dentry->d_name);
+			break;
+		}
+	}
+
+	closedir(dp);
+	free(path);
+	return vfio_id;
+}
+
+static char *vfio_noiommu_get_cdev_path(const char *bdf)
+{
+	char *vfio_id = vfio_noiommu_get_device_id(bdf);
+	char *cdev = NULL;
+
+	if (vfio_id) {
+		asprintf(&cdev, "/dev/vfio/devices/%s", vfio_id);
+		free(vfio_id);
+	}
+	return cdev;
+}
+
+static int vfio_device_bind_iommufd_ioctl(int cdev_fd, int iommufd)
+{
+	struct vfio_device_bind_iommufd bind_args = {
+		.argsz = sizeof(bind_args),
+		.iommufd = iommufd,
+	};
+
+	return ioctl(cdev_fd, VFIO_DEVICE_BIND_IOMMUFD, &bind_args);
+}
+
+static int vfio_device_get_info_ioctl(int cdev_fd,
+				      struct vfio_device_info *info)
+{
+	info->argsz = sizeof(*info);
+	return ioctl(cdev_fd, VFIO_DEVICE_GET_INFO, info);
+}
+
+static int vfio_device_ioas_alloc_ioctl(int iommufd,
+					struct iommu_ioas_alloc *alloc_args)
+{
+	alloc_args->size = sizeof(*alloc_args);
+	alloc_args->flags = 0;
+	return ioctl(iommufd, IOMMU_IOAS_ALLOC, alloc_args);
+}
+
+static int vfio_device_attach_iommufd_pt_ioctl(int cdev_fd, u32 pt_id)
+{
+	struct vfio_device_attach_iommufd_pt attach_args = {
+		.argsz = sizeof(attach_args),
+		.pt_id = pt_id,
+	};
+
+	return ioctl(cdev_fd, VFIO_DEVICE_ATTACH_IOMMUFD_PT, &attach_args);
+}
+
+static int vfio_device_detach_iommufd_pt_ioctl(int cdev_fd)
+{
+	struct vfio_device_detach_iommufd_pt detach_args = {
+		.argsz = sizeof(detach_args),
+	};
+
+	return ioctl(cdev_fd, VFIO_DEVICE_DETACH_IOMMUFD_PT, &detach_args);
+}
+
+static int vfio_device_get_region_info_ioctl(int cdev_fd, uint32_t index,
+					     struct vfio_region_info *info)
+{
+	info->argsz = sizeof(*info);
+	info->index = index;
+	return ioctl(cdev_fd, VFIO_DEVICE_GET_REGION_INFO, info);
+}
+
+static int vfio_device_reset_ioctl(int cdev_fd)
+{
+	return ioctl(cdev_fd, VFIO_DEVICE_RESET);
+}
+
+static int ioas_map_pages(int iommufd, uint32_t ioas_id, uint64_t iova,
+			  size_t length)
+{
+	struct iommu_ioas_map map_args = {
+		.size = sizeof(map_args),
+		.ioas_id = ioas_id,
+		.iova = iova,
+		.length = length,
+		.flags = IOMMU_IOAS_MAP_READABLE | IOMMU_IOAS_MAP_WRITEABLE | IOMMU_IOAS_MAP_FIXED_IOVA,
+	};
+	void *pages;
+	int ret;
+
+	/* Allocate test pages */
+	pages = mmap(NULL, length, PROT_READ | PROT_WRITE,
+		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+	if (pages == MAP_FAILED) {
+		printf("mmap failed for length 0x%lx\n", (unsigned long)length);
+		return -ENOMEM;
+	}
+
+	/* Set up page pointer for mapping */
+	map_args.user_va = (uintptr_t)pages;
+
+	printf("  ioas_map_pages: ioas_id=%u, iova=0x%lx, length=0x%lx, user_va=%p\n",
+	       ioas_id, (unsigned long)iova, (unsigned long)length, pages);
+
+	/* Map into IOAS */
+	ret = ioctl(iommufd, IOMMU_IOAS_MAP, &map_args);
+	if (ret != 0)
+		printf("  IOMMU_IOAS_MAP failed: %d (%s)\n", ret, strerror(errno));
+	else
+		printf("  IOMMU_IOAS_MAP succeeded\n");
+
+	munmap(pages, length);
+	return ret;
+}
+
+static int ioas_unmap_pages(int iommufd, uint32_t ioas_id, uint64_t iova,
+			    size_t length)
+{
+	struct iommu_ioas_unmap unmap_args = {
+		.size = sizeof(unmap_args),
+		.ioas_id = ioas_id,
+		.iova = iova,
+		.length = length,
+	};
+
+	return ioctl(iommufd, IOMMU_IOAS_UNMAP, &unmap_args);
+}
+
+static int ioas_destroy_ioctl(int iommufd, uint32_t ioas_id)
+{
+	struct iommu_destroy destroy_args = {
+		.size = sizeof(destroy_args),
+		.id = ioas_id,
+	};
+
+	return ioctl(iommufd, IOMMU_DESTROY, &destroy_args);
+}
+
+static int ioas_get_pa_ioctl(int iommufd, uint32_t ioas_id, uint64_t iova,
+			     uint64_t *phys_out, uint64_t *length_out)
+{
+	struct {
+		__u32 size;
+		__u32 flags;
+		__u32 ioas_id;
+		__u32 __reserved;
+		__u64 iova;
+		__u64 out_length;
+		__u64 out_phys;
+	} get_pa = {
+		.size = sizeof(get_pa),
+		.flags = 0,
+		.ioas_id = ioas_id,
+		.iova = iova,
+	};
+
+	printf("  ioas_get_pa_ioctl: ioas_id=%u, iova=0x%lx\n",
+	       ioas_id, (unsigned long)iova);
+
+	if (ioctl(iommufd, IOMMU_IOAS_GET_PA, &get_pa) != 0) {
+		printf("  IOMMU_IOAS_GET_PA failed: %s (errno=%d)\n",
+		       strerror(errno), errno);
+		return -1;
+	}
+
+	printf("  IOMMU_IOAS_GET_PA succeeded: PA=0x%lx, length=0x%lx\n",
+	       (unsigned long)get_pa.out_phys, (unsigned long)get_pa.out_length);
+
+	if (phys_out)
+		*phys_out = get_pa.out_phys;
+	if (length_out)
+		*length_out = get_pa.out_length;
+
+	return 0;
+}
+
+FIXTURE(vfio_noiommu) {
+	int cdev_fd;
+	int iommufd;
+};
+
+FIXTURE_SETUP(vfio_noiommu)
+{
+	ASSERT_LE(0, (self->cdev_fd = open(cdev_path, O_RDWR, 0)));
+	ASSERT_LE(0, (self->iommufd = open(iommu_dev_path, O_RDWR, 0)));
+}
+
+FIXTURE_TEARDOWN(vfio_noiommu)
+{
+	if (self->cdev_fd >= 0)
+		close(self->cdev_fd);
+	if (self->iommufd >= 0)
+		close(self->iommufd);
+}
+
+/*
+ * Test: Device cdev can be opened
+ */
+TEST_F(vfio_noiommu, device_cdev_open)
+{
+	ASSERT_LE(0, self->cdev_fd);
+}
+
+/*
+ * Test: Device can be bound to iommufd
+ */
+TEST_F(vfio_noiommu, device_bind_iommufd)
+{
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+}
+
+/*
+ * Test: Device info can be queried after binding
+ */
+TEST_F(vfio_noiommu, device_get_info_after_bind)
+{
+	struct vfio_device_info info;
+
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+	ASSERT_EQ(0, vfio_device_get_info_ioctl(self->cdev_fd, &info));
+	ASSERT_NE(0, info.argsz);
+}
+
+/*
+ * Test: Getting device info fails without bind
+ */
+TEST_F(vfio_noiommu, device_get_info_without_bind_fails)
+{
+	struct vfio_device_info info;
+
+	ASSERT_NE(0, vfio_device_get_info_ioctl(self->cdev_fd, &info));
+}
+
+/*
+ * Test: Binding with invalid iommufd fails
+ */
+TEST_F(vfio_noiommu, device_bind_bad_iommufd_fails)
+{
+	ASSERT_NE(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd, -2));
+}
+
+/*
+ * Test: Cannot bind twice to same device
+ */
+TEST_F(vfio_noiommu, device_repeated_bind_fails)
+{
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+	ASSERT_NE(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+}
+
+/*
+ * Test: IOAS can be allocated
+ */
+TEST_F(vfio_noiommu, ioas_alloc)
+{
+	struct iommu_ioas_alloc alloc_args;
+
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd,
+						  &alloc_args));
+	ASSERT_NE(0, alloc_args.out_ioas_id);
+}
+
+/*
+ * Test: IOAS can be destroyed
+ */
+TEST_F(vfio_noiommu, ioas_destroy)
+{
+	struct iommu_ioas_alloc alloc_args;
+
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd,
+						  &alloc_args));
+	ASSERT_EQ(0, ioas_destroy_ioctl(self->iommufd,
+					alloc_args.out_ioas_id));
+}
+
+/*
+ * Test: Device can attach to IOAS after binding
+ */
+TEST_F(vfio_noiommu, device_attach_to_ioas)
+{
+	struct iommu_ioas_alloc alloc_args;
+
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd,
+						  &alloc_args));
+	ASSERT_EQ(0, vfio_device_attach_iommufd_pt_ioctl(self->cdev_fd,
+							 alloc_args.out_ioas_id));
+}
+
+/*
+ * Test: Attaching to invalid IOAS fails
+ */
+TEST_F(vfio_noiommu, device_attach_invalid_ioas_fails)
+{
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+	ASSERT_NE(0, vfio_device_attach_iommufd_pt_ioctl(self->cdev_fd,
+							 UINT32_MAX));
+}
+
+/*
+ * Test: Device can detach from IOAS
+ */
+TEST_F(vfio_noiommu, device_detach_from_ioas)
+{
+	struct iommu_ioas_alloc alloc_args;
+
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd,
+						  &alloc_args));
+	ASSERT_EQ(0, vfio_device_attach_iommufd_pt_ioctl(self->cdev_fd,
+							 alloc_args.out_ioas_id));
+	ASSERT_EQ(0, vfio_device_detach_iommufd_pt_ioctl(self->cdev_fd));
+}
+
+/*
+ * Test: Full lifecycle - bind, attach, detach, reset
+ */
+TEST_F(vfio_noiommu, device_lifecycle)
+{
+	struct iommu_ioas_alloc alloc_args;
+	struct vfio_device_info info;
+
+	/* Bind device to iommufd */
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+
+	/* Allocate IOAS */
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd,
+						  &alloc_args));
+
+	/* Attach device to IOAS */
+	ASSERT_EQ(0, vfio_device_attach_iommufd_pt_ioctl(self->cdev_fd,
+							 alloc_args.out_ioas_id));
+
+	/* Query device info */
+	ASSERT_EQ(0, vfio_device_get_info_ioctl(self->cdev_fd, &info));
+
+	/* Detach device from IOAS */
+	ASSERT_EQ(0, vfio_device_detach_iommufd_pt_ioctl(self->cdev_fd));
+
+	/* Reset device */
+	ASSERT_EQ(0, vfio_device_reset_ioctl(self->cdev_fd));
+}
+
+/*
+ * Test: Get region info
+ */
+TEST_F(vfio_noiommu, device_get_region_info)
+{
+	struct vfio_device_info dev_info;
+	struct vfio_region_info region_info;
+
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+	ASSERT_EQ(0, vfio_device_get_info_ioctl(self->cdev_fd, &dev_info));
+
+	/* Try to get first region info if device has regions */
+	if (dev_info.num_regions > 0) {
+		ASSERT_EQ(0, vfio_device_get_region_info_ioctl(self->cdev_fd, 0,
+							       &region_info));
+		ASSERT_NE(0, region_info.argsz);
+	}
+}
+
+TEST_F(vfio_noiommu, device_reset)
+{
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+	ASSERT_EQ(0, vfio_device_reset_ioctl(self->cdev_fd));
+}
+
+TEST_F(vfio_noiommu, ioas_map_pages)
+{
+	struct iommu_ioas_alloc alloc_args;
+	long page_size = sysconf(_SC_PAGESIZE);
+	uint64_t iova = 0x10000;
+	int i;
+
+	ASSERT_GT(page_size, 0);
+
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd,
+						  &alloc_args));
+
+	printf("Page size: %ld bytes\n", page_size);
+	/* Test mapping regions of different sizes: 1, 2, 4, 8 pages */
+	for (i = 0; i < 4; i++) {
+		size_t map_size = page_size * (1 << i);  /* 1, 2, 4, 8 pages */
+		uint64_t test_iova = iova + (i * 0x100000);
+
+		/* Attempt to map each region (may fail if not supported) */
+		ioas_map_pages(self->iommufd, alloc_args.out_ioas_id,
+			       test_iova, map_size);
+	}
+}
+
+TEST_F(vfio_noiommu, multiple_ioas_alloc)
+{
+	struct iommu_ioas_alloc alloc1, alloc2;
+
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd, &alloc1));
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd, &alloc2));
+	ASSERT_NE(alloc1.out_ioas_id, alloc2.out_ioas_id);
+}
+
+/*
+ * Test: Query physical address for IOVA
+ * Tests IOMMU_IOAS_GET_PA ioctl to translate IOVA to physical address
+ * Note: Device must be attached to IOAS for PA query to work
+ */
+TEST_F(vfio_noiommu, ioas_get_pa_mapped)
+{
+	struct iommu_ioas_alloc alloc_args;
+	long page_size = sysconf(_SC_PAGESIZE);
+	uint64_t iova = 0x10000;
+	uint64_t phys = 0;
+	uint64_t length = 0;
+	int ret;
+
+	ASSERT_GT(page_size, 0);
+
+	ASSERT_EQ(0, vfio_device_bind_iommufd_ioctl(self->cdev_fd,
+						    self->iommufd));
+
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd,
+						  &alloc_args));
+
+	ASSERT_EQ(0, vfio_device_attach_iommufd_pt_ioctl(self->cdev_fd,
+							 alloc_args.out_ioas_id));
+
+	/* Map a page into an arbitrary IOAS, used as a cookie for lookup */
+	ret = ioas_map_pages(self->iommufd, alloc_args.out_ioas_id,
+			     iova, page_size);
+	if (ret != 0)
+		return;
+
+	/* Query the physical address for the mapped dummy IOVA */
+	ret = ioas_get_pa_ioctl(self->iommufd, alloc_args.out_ioas_id,
+			       iova, &phys, &length);
+
+	if (ret == 0) {
+		/* If we got a result, verify it's valid */
+		ASSERT_NE(0, phys);
+		ASSERT_GE(length, (uint64_t)page_size);
+	}
+}
+
+TEST_F(vfio_noiommu, ioas_get_pa_unmapped_fails)
+{
+	struct iommu_ioas_alloc alloc_args;
+
+	ASSERT_EQ(0, vfio_device_ioas_alloc_ioctl(self->iommufd,
+						  &alloc_args));
+
+	/* Try to retrieve unmapped IOVA (should fail) */
+	ASSERT_NE(0, ioas_get_pa_ioctl(self->iommufd, alloc_args.out_ioas_id,
+				       0x10000, NULL, NULL));
+}
+
+int main(int argc, char *argv[])
+{
+	const char *device_bdf = vfio_selftests_get_bdf(&argc, argv);
+	char *cdev = NULL;
+
+	if (!device_bdf) {
+		ksft_print_msg("No device BDF provided\n");
+		return KSFT_SKIP;
+	}
+
+	cdev = vfio_noiommu_get_cdev_path(device_bdf);
+	if (!cdev) {
+		ksft_print_msg("Could not find cdev for device %s\n",
+			       device_bdf);
+		return KSFT_SKIP;
+	}
+
+	cdev_path = cdev;
+	ksft_print_msg("Using cdev device %s for BDF %s\n", cdev_path,
+		       device_bdf);
+
+	return test_harness_run(argc, argv);
+}
-- 
2.34.1

[PATCH 11/11] Doc: Update VFIO NOIOMMU mode

[Jacob Pan]

Document the NOIOMMU mode with newly added cdev support under iommufd.

Signed-off-by: Jacob Pan <jacob.pan@linux.microsoft.com>
---
 Documentation/driver-api/vfio.rst | 44 +++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/Documentation/driver-api/vfio.rst b/Documentation/driver-api/vfio.rst
index 2a21a42c9386..d1ee13dc6e98 100644
--- a/Documentation/driver-api/vfio.rst
+++ b/Documentation/driver-api/vfio.rst
@@ -275,8 +275,6 @@ in a VFIO group.
 With CONFIG_VFIO_DEVICE_CDEV=y the user can now acquire a device fd
 by directly opening a character device /dev/vfio/devices/vfioX where
 "X" is the number allocated uniquely by VFIO for registered devices.
-cdev interface does not support noiommu devices, so user should use
-the legacy group interface if noiommu is wanted.
 
 The cdev only works with IOMMUFD.  Both VFIO drivers and applications
 must adapt to the new cdev security model which requires using
@@ -370,6 +368,48 @@ IOMMUFD IOAS/HWPT to enable userspace DMA::
 
 	/* Other device operations as stated in "VFIO Usage Example" */
 
+VFIO NOIOMMU mode
+-------------------------------------------------------------------------------
+VFIO also supports a no-IOMMU mode, intended for usages where unsafe DMA can
+be performed by userspace drivers w/o physical IOMMU protection. This mode
+is controlled by the parameter:
+
+/sys/module/vfio/parameters/enable_unsafe_noiommu_mode
+
+Upon enabling this mode, with an assigned device, the user will be presented
+with a VFIO group and device file, e.g.
+
+/dev/vfio/
+|-- devices
+|   `-- noiommu-vfio0	/* VFIO device cdev */
+|-- noiommu-0		/* VFIO group */
+`-- vfio
+
+The capabilities vary depending on the device programming interface and kernel
+configuration used. The following table summarizes the differences:
+
++-------------------+---------------------+---------------------+
+| Feature           | VFIO group          | VFIO device cdev   |
++===================+=====================+=====================+
+| VFIO device UAPI  | Yes                 | Yes                |
++-------------------+---------------------+---------------------+
+| VFIO container    | No                  | No                 |
++-------------------+---------------------+---------------------+
+| IOMMUFD IOAS      | No                  | Yes*               |
++-------------------+---------------------+---------------------+
+Note that the VFIO container case includes IOMMUFD provided VFIO compatibility
+interfaces when either CONFIG_VFIO_CONTAINER or CONFIG_IOMMUFD_VFIO_CONTAINER is
+enabled.
+
+* IOMMUFD UAPI is available for VFIO device cdev to pin and map user memory with
+the ability to retrieve physical addresses for DMA command submission.
+
+A new IOMMUFD ioctl IOMMU_IOAS_GET_PA is added to retrieve the physical address
+for a given user virtual address. Note that IOMMU_IOAS_MAP_FIXED_IOVA flag is
+ignored in no-IOMMU mode since there is no physical DMA remapping hardware.
+tools/testing/selftests/vfio/vfio_iommufd_noiommu_test.c provides an example of
+using this ioctl in no-IOMMU mode.
+
 VFIO User API
 -------------------------------------------------------------------------------
 
-- 
2.34.1

Re: [PATCH 00/11] iommufd: Enable noiommu mode for cdev

[Jason Gunthorpe]

On Fri, Feb 27, 2026 at 09:52:36AM -0800, Jacob Pan wrote:
> VFIO's unsafe_noiommu_mode has long provided a way for userspace drivers
> to operate on platforms lacking a hardware IOMMU. Today, IOMMUFD also
> supports No-IOMMU mode for group-based devices under vfio_compat mode.
> However, IOMMUFD's native character device (cdev) does not yet support
> No-IOMMU mode, which is the purpose of this patch.

I browsed through this quickly and it looks OK to me, though I might
suggest correcting that FIXME so that the get pa scans the domain for
contiguous physical address. You can copy the loop from vfio probably.

Also the kbuild error needs fixing, I gave a suggestion for that in
the thread.

Thanks,
Jason

Re: [PATCH 00/11] iommufd: Enable noiommu mode for cdev

[Jacob Pan]

Hi Jason,

On Mon, 2 Mar 2026 20:35:32 -0400
Jason Gunthorpe <jgg@nvidia.com> wrote:

> On Fri, Feb 27, 2026 at 09:52:36AM -0800, Jacob Pan wrote:
> > VFIO's unsafe_noiommu_mode has long provided a way for userspace
> > drivers to operate on platforms lacking a hardware IOMMU. Today,
> > IOMMUFD also supports No-IOMMU mode for group-based devices under
> > vfio_compat mode. However, IOMMUFD's native character device (cdev)
> > does not yet support No-IOMMU mode, which is the purpose of this
> > patch.  
> 
> I browsed through this quickly and it looks OK to me, though I might
> suggest correcting that FIXME so that the get pa scans the domain for
> contiguous physical address. You can copy the loop from vfio probably.
> 
Thanks for the suggestion, I will add the following to v2 and update
selftest with hugepage to cover this.

--- a/drivers/iommu/iommufd/io_pagetable.c
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -877,10 +877,19 @@ int iopt_get_phys(struct io_pagetable *iopt,
unsigned long iova, u64 *paddr, goto unlock_exit;
        }
        /*
-        * TBD: we can return contiguous IOVA length so that userspace
can
-        * keep searching for next physical address.
+        * Scan the domain for the contiguous physical address length
so that
+        * userspace search can be optimized for fewer ioctls.
         */
-       *length = PAGE_SIZE;
+       while (iova < iopt_area_last_iova(area)) {
+               u64 next_paddr =
iommu_iova_to_phys(area->storage_domain,
+                                                   iova + PAGE_SIZE);
+               if (!next_paddr || next_paddr != *paddr + PAGE_SIZE) {
+                       *length += PAGE_SIZE;
+                       break;
+               }
+               iova += PAGE_SIZE;
+               *paddr += PAGE_SIZE;
+       }
> Also the kbuild error needs fixing, I gave a suggestion for that in
> the thread.
will fix in v2.

Thanks again,

Jacob