[PATCH v1 0/2] iommufd: Allocate attach_handle for any HWPT

[PATCH v1 0/2] iommufd: Allocate attach_handle for any HWPT

[Nicolin Chen]

An attach_handle is a hwpt->fault specific thing, so the fault.c has been
holding a set of attach/detach/replace helpers for attach_handle and iopf
enabling/disabling.

Now, both the iommufd_msi series [1] and the attach_pasid series [2] want
to reuse the attach_handle for non-fault cases. Rework the attach_handle,
to prepare for either of the series. It should be merged with either that
gets merged first.

[1] https://lore.kernel.org/linux-iommu/cover.1736550979.git.nicolinc@nvidia.com/
[2] https://lore.kernel.org/linux-iommu/20241219132746.16193-1-yi.l.liu@intel.com/

Patches in this series are from [1] with some fixes addressing the review
comments.

Changelog
v1 (since [1])
 * Rebase on v6.14-rc1
 * Unwrap the fault attach/detach/replace helpers
 * Split the attach_handle patch to make it clearer

Thanks
Nicolin

Nicolin Chen (2):
  iommufd: Make attach_handle generic than fault specific
  iommufd/fault: Remove iommufd_fault_domain_attach/detach/replace_dev()

 drivers/iommu/iommufd/iommufd_private.h |  41 +-------
 drivers/iommu/iommufd/device.c          | 101 +++++++++++++++++++
 drivers/iommu/iommufd/fault.c           | 128 +-----------------------
 3 files changed, 109 insertions(+), 161 deletions(-)

-- 
2.43.0

[PATCH v1 1/2] iommufd: Make attach_handle generic than fault specific

[Nicolin Chen]

"attach_handle" was added exclusively for the iommufd_fault_iopf_handler()
used by IOPF/PRI use cases. Now, both the MSI and PASID series require to
reuse the attach_handle for non-fault cases.

Add a set of new attach/detach/replace helpers that does the attach_handle
allocation/releasing/replacement in the common path and also handles those
fault specific routines such as iopf enabling/disabling and auto response.

This covers both non-fault and fault cases in a clean way, replacing those
inline helpers in the header. The following patch will clean up those old
helpers in the fault.c file.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/iommufd/iommufd_private.h |  33 +-------
 drivers/iommu/iommufd/device.c          | 101 ++++++++++++++++++++++++
 drivers/iommu/iommufd/fault.c           |   8 +-
 3 files changed, 109 insertions(+), 33 deletions(-)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 0b1bafc7fd99..02fe1ada97cc 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -504,35 +504,10 @@ int iommufd_fault_domain_replace_dev(struct iommufd_device *idev,
 				     struct iommufd_hw_pagetable *hwpt,
 				     struct iommufd_hw_pagetable *old);
 
-static inline int iommufd_hwpt_attach_device(struct iommufd_hw_pagetable *hwpt,
-					     struct iommufd_device *idev)
-{
-	if (hwpt->fault)
-		return iommufd_fault_domain_attach_dev(hwpt, idev);
-
-	return iommu_attach_group(hwpt->domain, idev->igroup->group);
-}
-
-static inline void iommufd_hwpt_detach_device(struct iommufd_hw_pagetable *hwpt,
-					      struct iommufd_device *idev)
-{
-	if (hwpt->fault) {
-		iommufd_fault_domain_detach_dev(hwpt, idev);
-		return;
-	}
-
-	iommu_detach_group(hwpt->domain, idev->igroup->group);
-}
-
-static inline int iommufd_hwpt_replace_device(struct iommufd_device *idev,
-					      struct iommufd_hw_pagetable *hwpt,
-					      struct iommufd_hw_pagetable *old)
-{
-	if (old->fault || hwpt->fault)
-		return iommufd_fault_domain_replace_dev(idev, hwpt, old);
-
-	return iommu_group_replace_domain(idev->igroup->group, hwpt->domain);
-}
+int iommufd_fault_iopf_enable(struct iommufd_device *idev);
+void iommufd_fault_iopf_disable(struct iommufd_device *idev);
+void iommufd_auto_response_faults(struct iommufd_hw_pagetable *hwpt,
+				  struct iommufd_attach_handle *handle);
 
 static inline struct iommufd_viommu *
 iommufd_get_viommu(struct iommufd_ucmd *ucmd, u32 id)
diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index dfd0898fb6c1..360ba3ed8545 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -352,6 +352,107 @@ iommufd_device_attach_reserved_iova(struct iommufd_device *idev,
 	return 0;
 }
 
+/* The device attach/detach/replace helpers for attach_handle */
+
+static int iommufd_hwpt_attach_device(struct iommufd_hw_pagetable *hwpt,
+				      struct iommufd_device *idev)
+{
+	struct iommufd_attach_handle *handle;
+	int rc;
+
+	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
+	if (!handle)
+		return -ENOMEM;
+
+	if (hwpt->fault) {
+		rc = iommufd_fault_iopf_enable(idev);
+		if (rc)
+			goto out_free_handle;
+	}
+
+	handle->idev = idev;
+	rc = iommu_attach_group_handle(hwpt->domain, idev->igroup->group,
+				       &handle->handle);
+	if (rc)
+		goto out_disable_iopf;
+
+	return 0;
+
+out_disable_iopf:
+	if (hwpt->fault)
+		iommufd_fault_iopf_disable(idev);
+out_free_handle:
+	kfree(handle);
+	return rc;
+}
+
+static struct iommufd_attach_handle *
+iommufd_device_get_attach_handle(struct iommufd_device *idev)
+{
+	struct iommu_attach_handle *handle;
+
+	handle =
+		iommu_attach_handle_get(idev->igroup->group, IOMMU_NO_PASID, 0);
+	if (IS_ERR(handle))
+		return NULL;
+	return to_iommufd_handle(handle);
+}
+
+static void iommufd_hwpt_detach_device(struct iommufd_hw_pagetable *hwpt,
+				       struct iommufd_device *idev)
+{
+	struct iommufd_attach_handle *handle;
+
+	handle = iommufd_device_get_attach_handle(idev);
+	iommu_detach_group_handle(hwpt->domain, idev->igroup->group);
+	if (hwpt->fault) {
+		iommufd_auto_response_faults(hwpt, handle);
+		iommufd_fault_iopf_disable(idev);
+	}
+	kfree(handle);
+}
+
+static int iommufd_hwpt_replace_device(struct iommufd_device *idev,
+				       struct iommufd_hw_pagetable *hwpt,
+				       struct iommufd_hw_pagetable *old)
+{
+	struct iommufd_attach_handle *handle, *old_handle =
+		iommufd_device_get_attach_handle(idev);
+	int rc;
+
+	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
+	if (!handle)
+		return -ENOMEM;
+
+	if (hwpt->fault && !old->fault) {
+		rc = iommufd_fault_iopf_enable(idev);
+		if (rc)
+			goto out_free_handle;
+	}
+
+	handle->idev = idev;
+	rc = iommu_replace_group_handle(idev->igroup->group, hwpt->domain,
+					&handle->handle);
+	if (rc)
+		goto out_disable_iopf;
+
+	if (old->fault) {
+		iommufd_auto_response_faults(hwpt, old_handle);
+		if (!hwpt->fault)
+			iommufd_fault_iopf_disable(idev);
+	}
+	kfree(old_handle);
+
+	return 0;
+
+out_disable_iopf:
+	if (hwpt->fault && !old->fault)
+		iommufd_fault_iopf_disable(idev);
+out_free_handle:
+	kfree(handle);
+	return rc;
+}
+
 int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
 				struct iommufd_device *idev)
 {
diff --git a/drivers/iommu/iommufd/fault.c b/drivers/iommu/iommufd/fault.c
index d9a937450e55..cb844e6799d4 100644
--- a/drivers/iommu/iommufd/fault.c
+++ b/drivers/iommu/iommufd/fault.c
@@ -17,7 +17,7 @@
 #include "../iommu-priv.h"
 #include "iommufd_private.h"
 
-static int iommufd_fault_iopf_enable(struct iommufd_device *idev)
+int iommufd_fault_iopf_enable(struct iommufd_device *idev)
 {
 	struct device *dev = idev->dev;
 	int ret;
@@ -50,7 +50,7 @@ static int iommufd_fault_iopf_enable(struct iommufd_device *idev)
 	return ret;
 }
 
-static void iommufd_fault_iopf_disable(struct iommufd_device *idev)
+void iommufd_fault_iopf_disable(struct iommufd_device *idev)
 {
 	mutex_lock(&idev->iopf_lock);
 	if (!WARN_ON(idev->iopf_enabled == 0)) {
@@ -98,8 +98,8 @@ int iommufd_fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
 	return ret;
 }
 
-static void iommufd_auto_response_faults(struct iommufd_hw_pagetable *hwpt,
-					 struct iommufd_attach_handle *handle)
+void iommufd_auto_response_faults(struct iommufd_hw_pagetable *hwpt,
+				  struct iommufd_attach_handle *handle)
 {
 	struct iommufd_fault *fault = hwpt->fault;
 	struct iopf_group *group, *next;
-- 
2.43.0

Re: [PATCH v1 1/2] iommufd: Make attach_handle generic than fault specific

[Yi Liu]

On 2025/2/4 13:00, Nicolin Chen wrote:
> "attach_handle" was added exclusively for the iommufd_fault_iopf_handler()
> used by IOPF/PRI use cases. Now, both the MSI and PASID series require to
> reuse the attach_handle for non-fault cases.
> 
> Add a set of new attach/detach/replace helpers that does the attach_handle
> allocation/releasing/replacement in the common path and also handles those
> fault specific routines such as iopf enabling/disabling and auto response.
> 
> This covers both non-fault and fault cases in a clean way, replacing those
> inline helpers in the header. The following patch will clean up those old
> helpers in the fault.c file.
> 
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>   drivers/iommu/iommufd/iommufd_private.h |  33 +-------
>   drivers/iommu/iommufd/device.c          | 101 ++++++++++++++++++++++++
>   drivers/iommu/iommufd/fault.c           |   8 +-
>   3 files changed, 109 insertions(+), 33 deletions(-)

Reviewed-by: Yi Liu <yi.l.liu@intel.com>


-- 
Regards,
Yi Liu

Re: [PATCH v1 1/2] iommufd: Make attach_handle generic than fault specific

[Jason Gunthorpe]

On Mon, Feb 03, 2025 at 09:00:54PM -0800, Nicolin Chen wrote:
> "attach_handle" was added exclusively for the iommufd_fault_iopf_handler()
> used by IOPF/PRI use cases. Now, both the MSI and PASID series require to
> reuse the attach_handle for non-fault cases.
> 
> Add a set of new attach/detach/replace helpers that does the attach_handle
> allocation/releasing/replacement in the common path and also handles those
> fault specific routines such as iopf enabling/disabling and auto response.
> 
> This covers both non-fault and fault cases in a clean way, replacing those
> inline helpers in the header. The following patch will clean up those old
> helpers in the fault.c file.
> 
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>  drivers/iommu/iommufd/iommufd_private.h |  33 +-------
>  drivers/iommu/iommufd/device.c          | 101 ++++++++++++++++++++++++
>  drivers/iommu/iommufd/fault.c           |   8 +-
>  3 files changed, 109 insertions(+), 33 deletions(-)

I am going to add some lockdeps to this:

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 360ba3ed85455e..0786290b4056df 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -360,6 +360,8 @@ static int iommufd_hwpt_attach_device(struct iommufd_hw_pagetable *hwpt,
 	struct iommufd_attach_handle *handle;
 	int rc;
 
+	lockdep_assert_held(&idev->igroup->lock);
+
 	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
 	if (!handle)
 		return -ENOMEM;
@@ -391,6 +393,8 @@ iommufd_device_get_attach_handle(struct iommufd_device *idev)
 {
 	struct iommu_attach_handle *handle;
 
+	lockdep_assert_held(&idev->igroup->lock);
+
 	handle =
 		iommu_attach_handle_get(idev->igroup->group, IOMMU_NO_PASID, 0);
 	if (IS_ERR(handle))


I think the one in get_attach_handle is important to discourage misuse
of that ..

Thanks,
Jason

[PATCH v1 2/2] iommufd/fault: Remove iommufd_fault_domain_attach/detach/replace_dev()

[Nicolin Chen]

There are new attach/detach/replace helpers in device.c taking care of both
the attach_handle and the fault specific routines for iopf_enable/disable()
and auto response.

Clean up these redundant functions in the fault.c file.

Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/iommufd/iommufd_private.h |   8 --
 drivers/iommu/iommufd/fault.c           | 120 ------------------------
 2 files changed, 128 deletions(-)

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 02fe1ada97cc..8e0e3ab64747 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -496,14 +496,6 @@ int iommufd_fault_alloc(struct iommufd_ucmd *ucmd);
 void iommufd_fault_destroy(struct iommufd_object *obj);
 int iommufd_fault_iopf_handler(struct iopf_group *group);
 
-int iommufd_fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
-				    struct iommufd_device *idev);
-void iommufd_fault_domain_detach_dev(struct iommufd_hw_pagetable *hwpt,
-				     struct iommufd_device *idev);
-int iommufd_fault_domain_replace_dev(struct iommufd_device *idev,
-				     struct iommufd_hw_pagetable *hwpt,
-				     struct iommufd_hw_pagetable *old);
-
 int iommufd_fault_iopf_enable(struct iommufd_device *idev);
 void iommufd_fault_iopf_disable(struct iommufd_device *idev);
 void iommufd_auto_response_faults(struct iommufd_hw_pagetable *hwpt,
diff --git a/drivers/iommu/iommufd/fault.c b/drivers/iommu/iommufd/fault.c
index cb844e6799d4..931a3fbe6e32 100644
--- a/drivers/iommu/iommufd/fault.c
+++ b/drivers/iommu/iommufd/fault.c
@@ -60,44 +60,6 @@ void iommufd_fault_iopf_disable(struct iommufd_device *idev)
 	mutex_unlock(&idev->iopf_lock);
 }
 
-static int __fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
-				     struct iommufd_device *idev)
-{
-	struct iommufd_attach_handle *handle;
-	int ret;
-
-	handle = kzalloc(sizeof(*handle), GFP_KERNEL);
-	if (!handle)
-		return -ENOMEM;
-
-	handle->idev = idev;
-	ret = iommu_attach_group_handle(hwpt->domain, idev->igroup->group,
-					&handle->handle);
-	if (ret)
-		kfree(handle);
-
-	return ret;
-}
-
-int iommufd_fault_domain_attach_dev(struct iommufd_hw_pagetable *hwpt,
-				    struct iommufd_device *idev)
-{
-	int ret;
-
-	if (!hwpt->fault)
-		return -EINVAL;
-
-	ret = iommufd_fault_iopf_enable(idev);
-	if (ret)
-		return ret;
-
-	ret = __fault_domain_attach_dev(hwpt, idev);
-	if (ret)
-		iommufd_fault_iopf_disable(idev);
-
-	return ret;
-}
-
 void iommufd_auto_response_faults(struct iommufd_hw_pagetable *hwpt,
 				  struct iommufd_attach_handle *handle)
 {
@@ -135,88 +97,6 @@ void iommufd_auto_response_faults(struct iommufd_hw_pagetable *hwpt,
 	mutex_unlock(&fault->mutex);
 }
 
-static struct iommufd_attach_handle *
-iommufd_device_get_attach_handle(struct iommufd_device *idev)
-{
-	struct iommu_attach_handle *handle;
-
-	handle = iommu_attach_handle_get(idev->igroup->group, IOMMU_NO_PASID, 0);
-	if (IS_ERR(handle))
-		return NULL;
-
-	return to_iommufd_handle(handle);
-}
-
-void iommufd_fault_domain_detach_dev(struct iommufd_hw_pagetable *hwpt,
-				     struct iommufd_device *idev)
-{
-	struct iommufd_attach_handle *handle;
-
-	handle = iommufd_device_get_attach_handle(idev);
-	iommu_detach_group_handle(hwpt->domain, idev->igroup->group);
-	iommufd_auto_response_faults(hwpt, handle);
-	iommufd_fault_iopf_disable(idev);
-	kfree(handle);
-}
-
-static int __fault_domain_replace_dev(struct iommufd_device *idev,
-				      struct iommufd_hw_pagetable *hwpt,
-				      struct iommufd_hw_pagetable *old)
-{
-	struct iommufd_attach_handle *handle, *curr = NULL;
-	int ret;
-
-	if (old->fault)
-		curr = iommufd_device_get_attach_handle(idev);
-
-	if (hwpt->fault) {
-		handle = kzalloc(sizeof(*handle), GFP_KERNEL);
-		if (!handle)
-			return -ENOMEM;
-
-		handle->idev = idev;
-		ret = iommu_replace_group_handle(idev->igroup->group,
-						 hwpt->domain, &handle->handle);
-	} else {
-		ret = iommu_replace_group_handle(idev->igroup->group,
-						 hwpt->domain, NULL);
-	}
-
-	if (!ret && curr) {
-		iommufd_auto_response_faults(old, curr);
-		kfree(curr);
-	}
-
-	return ret;
-}
-
-int iommufd_fault_domain_replace_dev(struct iommufd_device *idev,
-				     struct iommufd_hw_pagetable *hwpt,
-				     struct iommufd_hw_pagetable *old)
-{
-	bool iopf_off = !hwpt->fault && old->fault;
-	bool iopf_on = hwpt->fault && !old->fault;
-	int ret;
-
-	if (iopf_on) {
-		ret = iommufd_fault_iopf_enable(idev);
-		if (ret)
-			return ret;
-	}
-
-	ret = __fault_domain_replace_dev(idev, hwpt, old);
-	if (ret) {
-		if (iopf_on)
-			iommufd_fault_iopf_disable(idev);
-		return ret;
-	}
-
-	if (iopf_off)
-		iommufd_fault_iopf_disable(idev);
-
-	return 0;
-}
-
 void iommufd_fault_destroy(struct iommufd_object *obj)
 {
 	struct iommufd_fault *fault = container_of(obj, struct iommufd_fault, obj);
-- 
2.43.0

Re: [PATCH v1 2/2] iommufd/fault: Remove iommufd_fault_domain_attach/detach/replace_dev()

[Yi Liu]

On 2025/2/4 13:00, Nicolin Chen wrote:
> There are new attach/detach/replace helpers in device.c taking care of both
> the attach_handle and the fault specific routines for iopf_enable/disable()
> and auto response.
> 
> Clean up these redundant functions in the fault.c file.
> 
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> ---
>   drivers/iommu/iommufd/iommufd_private.h |   8 --
>   drivers/iommu/iommufd/fault.c           | 120 ------------------------
>   2 files changed, 128 deletions(-)

Reviewed-by: Yi Liu <yi.l.liu@intel.com>


-- 
Regards,
Yi Liu

Re: [PATCH v1 0/2] iommufd: Allocate attach_handle for any HWPT

[Jason Gunthorpe]

On Mon, Feb 03, 2025 at 09:00:53PM -0800, Nicolin Chen wrote:
> An attach_handle is a hwpt->fault specific thing, so the fault.c has been
> holding a set of attach/detach/replace helpers for attach_handle and iopf
> enabling/disabling.
> 
> Now, both the iommufd_msi series [1] and the attach_pasid series [2] want
> to reuse the attach_handle for non-fault cases. Rework the attach_handle,
> to prepare for either of the series. It should be merged with either that
> gets merged first.
> 
> [1] https://lore.kernel.org/linux-iommu/cover.1736550979.git.nicolinc@nvidia.com/
> [2] https://lore.kernel.org/linux-iommu/20241219132746.16193-1-yi.l.liu@intel.com/
> 
> Patches in this series are from [1] with some fixes addressing the review
> comments.

Applied, the other patches can rebase on top of this

Thanks,
Jason