Nouveau - Sep 2024 - [PATCH v2 0/3] drm: Use iommu_paging_domain_alloc()

Commit <17de3f5fdd35> ("iommu: Retire bus ops") removes iommu
ops from
the bus structure. The iommu subsystem no longer relies on bus for
operations. So iommu_domain_alloc() interface is no longer relevant.

A new helper named iommu_paging_domain_alloc() was introduced in the
iommu subsystem as a replacement of iommu_domain_alloc(). This helper
relies on the device for IOMMU API use instead of the bus.

The replacement work started from this series:

https://lore.kernel.org/linux-iommu/20240610085555.88197-1-baolu.lu at
linux.intel.com/

Several patches have already been merged into the mainline kernel, but
we've decided to route all remaining ones through the subsystem tree.

Change log:
v2:
 - Patch 3/3: use dev->dev.parent as the input for
   iommu_paging_domain_alloc(), suggested by Thierry Reding.
  
https://lore.kernel.org/linux-iommu/qyvyd2ftebjlgmzyayfvxsqa64c4wgx7keix3a6eexdspbvawy
at a5ffnm5h5tgp/

v1:
 - https://lore.kernel.org/linux-iommu/20240812071034.9443-1-baolu.lu at
linux.intel.com/

Lu Baolu (3):
  drm/nouveau/tegra: Use iommu_paging_domain_alloc()
  drm/rockchip: Use iommu_paging_domain_alloc()
  drm/tegra: Use iommu_paging_domain_alloc()

 drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c |  4 ++--
 drivers/gpu/drm/rockchip/rockchip_drm_drv.c        | 10 +++++++---
 drivers/gpu/drm/tegra/drm.c                        |  5 +++--
 3 files changed, 12 insertions(+), 7 deletions(-)

-- 
2.34.1

In nvkm_device_tegra_probe_iommu(), a paging domain is allocated for @dev
and attached to it on success. Use iommu_paging_domain_alloc() to make it
explicit.

Signed-off-by: Lu Baolu <baolu.lu at linux.intel.com>
---
 drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c
b/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c
index 87caa4a72921..763c4c2925f9 100644
--- a/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c
+++ b/drivers/gpu/drm/nouveau/nvkm/engine/device/tegra.c
@@ -120,8 +120,8 @@ nvkm_device_tegra_probe_iommu(struct nvkm_device_tegra
*tdev)
 	mutex_init(&tdev->iommu.mutex);
 
 	if (device_iommu_mapped(dev)) {
-		tdev->iommu.domain = iommu_domain_alloc(&platform_bus_type);
-		if (!tdev->iommu.domain)
+		tdev->iommu.domain = iommu_paging_domain_alloc(dev);
+		if (IS_ERR(tdev->iommu.domain))
 			goto error;
 
 		/*
-- 
2.34.1

Commit <421be3ee36a4> ("drm/rockchip: Refactor IOMMU
initialisation") has
refactored rockchip_drm_init_iommu() to pass a device that the domain is
allocated for. Replace iommu_domain_alloc() with
iommu_paging_domain_alloc() to retire the former.

Signed-off-by: Lu Baolu <baolu.lu at linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>
Acked-by: Andy Yan <andyshrk at 163.com>
---
 drivers/gpu/drm/rockchip/rockchip_drm_drv.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index 44d769d9234d..11e5d10de4d7 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -103,13 +103,17 @@ static int rockchip_drm_init_iommu(struct drm_device
*drm_dev)
 	struct rockchip_drm_private *private = drm_dev->dev_private;
 	struct iommu_domain_geometry *geometry;
 	u64 start, end;
+	int ret;
 
 	if (IS_ERR_OR_NULL(private->iommu_dev))
 		return 0;
 
-	private->domain = iommu_domain_alloc(private->iommu_dev->bus);
-	if (!private->domain)
-		return -ENOMEM;
+	private->domain = iommu_paging_domain_alloc(private->iommu_dev);
+	if (IS_ERR(private->domain)) {
+		ret = PTR_ERR(private->domain);
+		private->domain = NULL;
+		return ret;
+	}
 
 	geometry = &private->domain->geometry;
 	start = geometry->aperture_start;
-- 
2.34.1

Commit <17de3f5fdd35> ("iommu: Retire bus ops") removes iommu
ops from
the bus structure. The iommu subsystem no longer relies on bus for
operations. So iommu_domain_alloc() interface is no longer relevant.

Replace iommu_domain_alloc() with iommu_paging_domain_alloc() which takes
the physical device from which the host1x_device virtual device was
instantiated. This physical device is a common parent to all physical
devices that are part of the virtual device.

Suggested-by: Thierry Reding <thierry.reding at gmail.com>
Signed-off-by: Lu Baolu <baolu.lu at linux.intel.com>
---
 drivers/gpu/drm/tegra/drm.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tegra/drm.c b/drivers/gpu/drm/tegra/drm.c
index 03d1c76aec2d..d79c76a287f2 100644
--- a/drivers/gpu/drm/tegra/drm.c
+++ b/drivers/gpu/drm/tegra/drm.c
@@ -1135,6 +1135,7 @@ static bool host1x_drm_wants_iommu(struct host1x_device
*dev)
 
 static int host1x_drm_probe(struct host1x_device *dev)
 {
+	struct device *dma_dev = dev->dev.parent;
 	struct tegra_drm *tegra;
 	struct drm_device *drm;
 	int err;
@@ -1149,8 +1150,8 @@ static int host1x_drm_probe(struct host1x_device *dev)
 		goto put;
 	}
 
-	if (host1x_drm_wants_iommu(dev) &&
iommu_present(&platform_bus_type)) {
-		tegra->domain = iommu_domain_alloc(&platform_bus_type);
+	if (host1x_drm_wants_iommu(dev) && device_iommu_mapped(dma_dev)) {
+		tegra->domain = iommu_paging_domain_alloc(dma_dev);
 		if (!tegra->domain) {
 			err = -ENOMEM;
 			goto free;
-- 
2.34.1