[PATCH 1/4] iommu: Add a broken_unmanaged_domain flag in iommu_ops

[Nicolin Chen <nicolinc@nvidia.com>]

Both IOMMU_DOMAIN_UNMANAGED and IOMMU_DOMAIN_DMA require the support
of __IOMMU_DOMAIN_PAGING capability, i.e. iommu_map/unmap. However,
some older iommu drivers do not fully support that, and these drivers
also do not advertise support for dma-iommu.c via IOMMU_DOMAIN_DMA,
or use arm_iommu_create_mapping(), so largely their implementations
of IOMMU_DOMAIN_UNMANAGED are untested. This means that a user like
vfio/iommufd does not likely work with them.

Several of them have obvious problems:
  * fsl_pamu_domain.c
    Without map/unmap ops in the default_domain_ops, it isn't an
    unmanaged domain at all.
  * mtk_iommu_v1.c
    With a fixed 4M "pagetable", it can only map exactly 4G of
    memory, but doesn't set the aperture.
  * tegra-gart.c
    Its notion of attach/detach and groups has to be a complete lie to
    get around all the other API expectations.

Some others might work but have never been tested with vfio/iommufd:
  * msm_iommu.c
  * omap-iommu.c
  * tegra-smmu.c

Thus, mark all these drivers as having "broken" UNAMANGED domains and
add a new device_iommu_unmanaged_supported() API for vfio/iommufd and
dma-iommu to refuse to work with these drivers.

Co-developed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
---
 drivers/iommu/fsl_pamu_domain.c |  1 +
 drivers/iommu/iommu.c           | 24 ++++++++++++++++++++++++
 drivers/iommu/msm_iommu.c       |  1 +
 drivers/iommu/mtk_iommu_v1.c    |  1 +
 drivers/iommu/omap-iommu.c      |  1 +
 drivers/iommu/tegra-gart.c      |  1 +
 drivers/iommu/tegra-smmu.c      |  1 +
 include/linux/iommu.h           | 11 +++++++++++
 8 files changed, 41 insertions(+)

diff --git a/drivers/iommu/fsl_pamu_domain.c b/drivers/iommu/fsl_pamu_domain.c
index 4408ac3c49b6..1f3a4c8c78ad 100644
--- a/drivers/iommu/fsl_pamu_domain.c
+++ b/drivers/iommu/fsl_pamu_domain.c
@@ -448,6 +448,7 @@ static struct iommu_device *fsl_pamu_probe_device(struct device *dev)
 }
 
 static const struct iommu_ops fsl_pamu_ops = {
+	.broken_unmanaged_domain = true,
 	.capable	= fsl_pamu_capable,
 	.domain_alloc	= fsl_pamu_domain_alloc,
 	.probe_device	= fsl_pamu_probe_device,
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 5f6a85aea501..648fc04143b8 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1897,6 +1897,30 @@ bool device_iommu_capable(struct device *dev, enum iommu_cap cap)
 }
 EXPORT_SYMBOL_GPL(device_iommu_capable);
 
+/**
+ * device_iommu_unmanaged_supported() - full support of IOMMU_DOMAIN_UNMANAGED
+ * @dev: device that is behind the iommu
+ *
+ * In general, all IOMMU drivers can allocate IOMMU_DOMAIN_UNMANAGED domains.
+ * However, some of them set the broken_unmanaged_domain, indicating something
+ * is wrong about its support of IOMMU_DOMAIN_UNMANAGED/__IOMMU_DOMAIN_PAGING.
+ * This can happen, when a driver lies about the support to get around with the
+ * IOMMU API, merely for other drivers to use, or when a driver has never been
+ * tested with vfio/iommufd that need a full support of IOMMU_DOMAIN_UNMANAGED.
+ *
+ * Return: true if an IOMMU is present and broken_unmanaged_domain is not set,
+ *         otherwise, false.
+ */
+bool device_iommu_unmanaged_supported(struct device *dev)
+{
+	if (dev->iommu && dev->iommu->iommu_dev &&
+	    !dev_iommu_ops(dev)->broken_unmanaged_domain)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(device_iommu_unmanaged_supported);
+
 /**
  * iommu_set_fault_handler() - set a fault handler for an iommu domain
  * @domain: iommu domain
diff --git a/drivers/iommu/msm_iommu.c b/drivers/iommu/msm_iommu.c
index c60624910872..9c0bd5aee10b 100644
--- a/drivers/iommu/msm_iommu.c
+++ b/drivers/iommu/msm_iommu.c
@@ -675,6 +675,7 @@ irqreturn_t msm_iommu_fault_handler(int irq, void *dev_id)
 }
 
 static struct iommu_ops msm_iommu_ops = {
+	.broken_unmanaged_domain = true,
 	.domain_alloc = msm_iommu_domain_alloc,
 	.probe_device = msm_iommu_probe_device,
 	.device_group = generic_device_group,
diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index ca581ff1c769..c2ecbff6592c 100644
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -578,6 +578,7 @@ static int mtk_iommu_v1_hw_init(const struct mtk_iommu_v1_data *data)
 }
 
 static const struct iommu_ops mtk_iommu_v1_ops = {
+	.broken_unmanaged_domain = true,
 	.domain_alloc	= mtk_iommu_v1_domain_alloc,
 	.probe_device	= mtk_iommu_v1_probe_device,
 	.probe_finalize = mtk_iommu_v1_probe_finalize,
diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c
index 2fd7702c6709..17ed392b9f63 100644
--- a/drivers/iommu/omap-iommu.c
+++ b/drivers/iommu/omap-iommu.c
@@ -1733,6 +1733,7 @@ static struct iommu_group *omap_iommu_device_group(struct device *dev)
 }
 
 static const struct iommu_ops omap_iommu_ops = {
+	.broken_unmanaged_domain = true,
 	.domain_alloc	= omap_iommu_domain_alloc,
 	.probe_device	= omap_iommu_probe_device,
 	.release_device	= omap_iommu_release_device,
diff --git a/drivers/iommu/tegra-gart.c b/drivers/iommu/tegra-gart.c
index ed53279d1106..9af56d2ec6c1 100644
--- a/drivers/iommu/tegra-gart.c
+++ b/drivers/iommu/tegra-gart.c
@@ -267,6 +267,7 @@ static void gart_iommu_sync(struct iommu_domain *domain,
 }
 
 static const struct iommu_ops gart_iommu_ops = {
+	.broken_unmanaged_domain = true,
 	.domain_alloc	= gart_iommu_domain_alloc,
 	.probe_device	= gart_iommu_probe_device,
 	.device_group	= generic_device_group,
diff --git a/drivers/iommu/tegra-smmu.c b/drivers/iommu/tegra-smmu.c
index 5b1af40221ec..d1e4c4825d74 100644
--- a/drivers/iommu/tegra-smmu.c
+++ b/drivers/iommu/tegra-smmu.c
@@ -962,6 +962,7 @@ static int tegra_smmu_of_xlate(struct device *dev,
 }
 
 static const struct iommu_ops tegra_smmu_ops = {
+	.broken_unmanaged_domain = true,
 	.domain_alloc = tegra_smmu_domain_alloc,
 	.probe_device = tegra_smmu_probe_device,
 	.device_group = tegra_smmu_device_group,
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 46e1347bfa22..919a5dbad75b 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -245,6 +245,10 @@ struct iommu_iotlb_gather {
  *                    pasid, so that any DMA transactions with this pasid
  *                    will be blocked by the hardware.
  * @pgsize_bitmap: bitmap of all possible supported page sizes
+ * @broken_unmanaged_domain: IOMMU_DOMAIN_UNMANAGED is not fully functional; the
+ *                           driver does not really support iommu_map/unmap, but
+ *                           uses UNMANAGED domains for the IOMMU API, called by
+ *                           other SOC drivers.
  * @owner: Driver module providing these ops
  */
 struct iommu_ops {
@@ -277,6 +281,7 @@ struct iommu_ops {
 
 	const struct iommu_domain_ops *default_domain_ops;
 	unsigned long pgsize_bitmap;
+	bool broken_unmanaged_domain;
 	struct module *owner;
 };
 
@@ -455,6 +460,7 @@ static inline const struct iommu_ops *dev_iommu_ops(struct device *dev)
 extern int bus_iommu_probe(struct bus_type *bus);
 extern bool iommu_present(struct bus_type *bus);
 extern bool device_iommu_capable(struct device *dev, enum iommu_cap cap);
+extern bool device_iommu_unmanaged_supported(struct device *dev);
 extern struct iommu_domain *iommu_domain_alloc(struct bus_type *bus);
 extern struct iommu_group *iommu_group_get_by_id(int id);
 extern void iommu_domain_free(struct iommu_domain *domain);
@@ -742,6 +748,11 @@ static inline bool device_iommu_capable(struct device *dev, enum iommu_cap cap)
 	return false;
 }
 
+static inline bool device_iommu_unmanaged_supported(struct device *dev)
+{
+	return false;
+}
+
 static inline struct iommu_domain *iommu_domain_alloc(struct bus_type *bus)
 {
 	return NULL;
-- 
2.39.1