linux-kernel - [PATCH 05/20] iommu: Add iommu_paging_domain

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Date: Wed, 29 May 2024 13:32:35 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Kevin Tian <kevin.tian@...el.com>
Cc: Yi Liu <yi.l.liu@...el.com>,
	David Airlie <airlied@...il.com>,
	Daniel Vetter <daniel@...ll.ch>,
	Kalle Valo <kvalo@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Mathieu Poirier <mathieu.poirier@...aro.org>,
	Alex Williamson <alex.williamson@...hat.com>,
	mst@...hat.com,
	Jason Wang <jasowang@...hat.com>,
	Thierry Reding <thierry.reding@...il.com>,
	Jonathan Hunter <jonathanh@...dia.com>,
	Mikko Perttunen <mperttunen@...dia.com>,
	iommu@...ts.linux.dev,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 05/20] iommu: Add iommu_paging_domain_alloc() interface

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

Add a new interface named iommu_paging_domain_alloc(), which explicitly
indicates the allocation of a paging domain for DMA managed by a kernel
driver. The new interface takes a device pointer as its parameter, that
better aligns with the current iommu subsystem.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 include/linux/iommu.h |  6 ++++++
 drivers/iommu/iommu.c | 20 ++++++++++++++++++++
 2 files changed, 26 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 6648b2415474..16401de7802d 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -781,6 +781,7 @@ extern bool device_iommu_capable(struct device *dev, enum iommu_cap cap);
 extern bool iommu_group_has_isolated_msi(struct iommu_group *group);
 extern struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus);
 struct iommu_domain *iommu_user_domain_alloc(struct device *dev, u32 flags);
+struct iommu_domain *iommu_paging_domain_alloc(struct device *dev);
 extern void iommu_domain_free(struct iommu_domain *domain);
 extern int iommu_attach_device(struct iommu_domain *domain,
 			       struct device *dev);
@@ -1092,6 +1093,11 @@ static inline struct iommu_domain *iommu_user_domain_alloc(struct device *dev, u
 	return ERR_PTR(-ENODEV);
 }
 
+static inline struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
+{
+	return ERR_PTR(-ENODEV);
+}
+
 static inline void iommu_domain_free(struct iommu_domain *domain)
 {
 }
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index f1416892ef8e..7df4a021b040 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2016,6 +2016,10 @@ static int __iommu_domain_alloc_dev(struct device *dev, void *data)
 	return 0;
 }
 
+/*
+ * The iommu ops in bus has been retired. Do not use this interface in
+ * new drivers.
+ */
 struct iommu_domain *iommu_domain_alloc(const struct bus_type *bus)
 {
 	const struct iommu_ops *ops = NULL;
@@ -2074,6 +2078,22 @@ struct iommu_domain *iommu_user_domain_alloc(struct device *dev, u32 flags)
 }
 EXPORT_SYMBOL_GPL(iommu_user_domain_alloc);
 
+/**
+ * iommu_paging_domain_alloc() - Allocate a paging domain
+ * @dev: device for which the domain is allocated
+ *
+ * Allocate a paging domain which will be managed by a kernel driver. Return
+ * allocated domain if successful, or a ERR pointer for failure.
+ */
+struct iommu_domain *iommu_paging_domain_alloc(struct device *dev)
+{
+	if (!dev_has_iommu(dev))
+		return ERR_PTR(-ENODEV);
+
+	return __iommu_domain_alloc(dev_iommu_ops(dev), dev, IOMMU_DOMAIN_UNMANAGED);
+}
+EXPORT_SYMBOL_GPL(iommu_paging_domain_alloc);
+
 void iommu_domain_free(struct iommu_domain *domain)
 {
 	if (domain->type == IOMMU_DOMAIN_SVA)
-- 
2.34.1