Message-ID: <20240828061104.1925127-3-hch@lst.de>
Date: Wed, 28 Aug 2024 09:10:29 +0300
From: Christoph Hellwig <hch@....de>
To: iommu@...ts.linux.dev
Cc: Marek Szyprowski <m.szyprowski@...sung.com>,
	Robin Murphy <robin.murphy@....com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Bingbu Cao <bingbu.cao@...el.com>,
	"Michael S . Tsirkin " <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	linux-kernel@...r.kernel.org,
	linux-alpha@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mips@...r.kernel.org,
	linux-parisc@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	linux-s390@...r.kernel.org,
	sparclinux@...r.kernel.org,
	linux-media@...r.kernel.org,
	virtualization@...ts.linux.dev,
	xen-devel@...ts.xenproject.org,
	Thomas Gleixner <tglx@...utronix.de>
Subject: [PATCH 2/2] dma-mapping: clearly mark DMA ops as an architecture feature

DMA ops are a helper for architectures and not for drivers to override
the DMA implementation.

Unfortunately driver authors keep ignoring this.  Make the fact more
clear by renaming the symbol to ARCH_HAS_DMA_OPS and having the two drivers
overriding their dma_ops depend on that.  These drivers should probably be
marked broken, but we can give them a bit of a grace period for that.

Signed-off-by: Christoph Hellwig <hch@....de>
Reviewed-by: Thomas Gleixner <tglx@...utronix.de>
Acked-by: Sakari Ailus <sakari.ailus@...ux.intel.com> # for IPU6
Acked-by: Robin Murphy <robin.murphy@....com>
---
 arch/Kconfig                         | 9 +++++++++
 arch/alpha/Kconfig                   | 2 +-
 arch/arm/Kconfig                     | 2 +-
 arch/arm64/Kconfig                   | 1 +
 arch/mips/Kconfig                    | 2 +-
 arch/parisc/Kconfig                  | 2 +-
 arch/powerpc/Kconfig                 | 2 +-
 arch/s390/Kconfig                    | 2 +-
 arch/sparc/Kconfig                   | 2 +-
 arch/x86/Kconfig                     | 2 +-
 drivers/macintosh/macio_asic.c       | 4 ++--
 drivers/media/pci/intel/ipu6/Kconfig | 7 ++++++-
 drivers/vdpa/Kconfig                 | 7 ++++++-
 drivers/xen/Kconfig                  | 4 ++--
 include/linux/device.h               | 2 +-
 include/linux/dma-map-ops.h          | 6 +++---
 kernel/dma/Kconfig                   | 9 ++-------
 kernel/dma/Makefile                  | 2 +-
 18 files changed, 41 insertions(+), 26 deletions(-)

diff --git a/arch/Kconfig b/arch/Kconfig
index 975dd22a2dbd22..61c4ec04878754 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -17,6 +17,15 @@ config CPU_MITIGATIONS
 	def_bool y
 endif
 
+#
+# Selected by architectures that need custom DMA operations for e.g. legacy
+# IOMMUs not handled by dma-iommu.  Drivers must never select this symbol.
+#
+config ARCH_HAS_DMA_OPS
+	depends on HAS_DMA
+	select DMA_OPS_HELPERS
+	bool
+
 menu "General architecture-dependent options"
 
 config ARCH_HAS_SUBPAGE_FAULTS
diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
index 50ff06d5b799c9..109a4cddcd1389 100644
--- a/arch/alpha/Kconfig
+++ b/arch/alpha/Kconfig
@@ -4,12 +4,12 @@ config ALPHA
 	default y
 	select ARCH_32BIT_USTAT_F_TINODE
 	select ARCH_HAS_CURRENT_STACK_POINTER
+	select ARCH_HAS_DMA_OPS if PCI
 	select ARCH_MIGHT_HAVE_PC_PARPORT
 	select ARCH_MIGHT_HAVE_PC_SERIO
 	select ARCH_NO_PREEMPT
 	select ARCH_NO_SG_CHAIN
 	select ARCH_USE_CMPXCHG_LOCKREF
-	select DMA_OPS if PCI
 	select FORCE_PCI
 	select PCI_DOMAINS if PCI
 	select PCI_SYSCALL if PCI
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 54b2bb817a7fc0..f5f7995a2f8f59 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -10,6 +10,7 @@ config ARM
 	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VIRTUAL if MMU
 	select ARCH_HAS_DMA_ALLOC if MMU
+	select ARCH_HAS_DMA_OPS
 	select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FORTIFY_SOURCE
@@ -54,7 +55,6 @@ config ARM
 	select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
 	select DMA_DECLARE_COHERENT
 	select DMA_GLOBAL_POOL if !MMU
-	select DMA_OPS
 	select DMA_NONCOHERENT_MMAP if MMU
 	select EDAC_SUPPORT
 	select EDAC_ATOMIC_SCRUB
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a2f8ff354ca670..40940cbde435a3 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -24,6 +24,7 @@ config ARM64
 	select ARCH_HAS_CURRENT_STACK_POINTER
 	select ARCH_HAS_DEBUG_VIRTUAL
 	select ARCH_HAS_DEBUG_VM_PGTABLE
+	select ARCH_HAS_DMA_OPS if XEN
 	select ARCH_HAS_DMA_PREP_COHERENT
 	select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
 	select ARCH_HAS_FAST_MULTIPLIER
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 60077e57693563..023ad33a7e945d 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -8,6 +8,7 @@ config MIPS
 	select ARCH_HAS_CPU_FINALIZE_INIT
 	select ARCH_HAS_CURRENT_STACK_POINTER if !CC_IS_CLANG || CLANG_VERSION >= 140000
 	select ARCH_HAS_DEBUG_VIRTUAL if !64BIT
+	select ARCH_HAS_DMA_OPS if MACH_JAZZ
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE if !EVA
@@ -393,7 +394,6 @@ config MACH_JAZZ
 	select ARC_PROMLIB
 	select ARCH_MIGHT_HAVE_PC_PARPORT
 	select ARCH_MIGHT_HAVE_PC_SERIO
-	select DMA_OPS
 	select FW_ARC
 	select FW_ARC32
 	select ARCH_MAY_HAVE_PC_FDC
diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index b0a2ac3ba91610..859835a0692c24 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -10,6 +10,7 @@ config PARISC
 	select ARCH_WANT_FRAME_POINTERS
 	select ARCH_HAS_CPU_CACHE_ALIASING
 	select ARCH_HAS_DMA_ALLOC if PA11
+	select ARCH_HAS_DMA_OPS
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_STRICT_KERNEL_RWX
 	select ARCH_HAS_STRICT_MODULE_RWX
@@ -23,7 +24,6 @@ config PARISC
 	select ARCH_HAS_CACHE_LINE_SIZE
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select HAVE_RELIABLE_STACKTRACE
-	select DMA_OPS
 	select RTC_CLASS
 	select RTC_DRV_GENERIC
 	select INIT_ALL_POSSIBLE
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index d7b09b064a8ac5..f87fc0375a92b3 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -133,6 +133,7 @@ config PPC
 	select ARCH_HAS_DEBUG_WX		if STRICT_KERNEL_RWX
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_DMA_MAP_DIRECT 		if PPC_PSERIES
+	select ARCH_HAS_DMA_OPS			if PPC64
 	select ARCH_HAS_FORTIFY_SOURCE
 	select ARCH_HAS_GCOV_PROFILE_ALL
 	select ARCH_HAS_KCOV
@@ -185,7 +186,6 @@ config PPC
 	select CPUMASK_OFFSTACK			if NR_CPUS >= 8192
 	select DCACHE_WORD_ACCESS		if PPC64 && CPU_LITTLE_ENDIAN
 	select DMA_OPS_BYPASS			if PPC64
-	select DMA_OPS				if PPC64
 	select DYNAMIC_FTRACE			if FUNCTION_TRACER
 	select EDAC_ATOMIC_SCRUB
 	select EDAC_SUPPORT
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index a822f952f64a9c..f31f6b85c25ccc 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -70,6 +70,7 @@ config S390
 	select ARCH_HAS_DEBUG_VM_PGTABLE
 	select ARCH_HAS_DEBUG_WX
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
+	select ARCH_HAS_DMA_OPS if PCI
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FORCE_DMA_UNENCRYPTED
 	select ARCH_HAS_FORTIFY_SOURCE
@@ -137,7 +138,6 @@ config S390
 	select BUILDTIME_TABLE_SORT
 	select CLONE_BACKWARDS2
 	select DCACHE_WORD_ACCESS if !KMSAN
-	select DMA_OPS if PCI
 	select DYNAMIC_FTRACE if FUNCTION_TRACER
 	select FUNCTION_ALIGNMENT_8B if CC_IS_GCC
 	select FUNCTION_ALIGNMENT_16B if !CC_IS_GCC
diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index 11bf9d312318c6..dcfdb7f1dae976 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -14,9 +14,9 @@ config SPARC
 	bool
 	default y
 	select ARCH_HAS_CPU_CACHE_ALIASING
+	select ARCH_HAS_DMA_OPS
 	select ARCH_MIGHT_HAVE_PC_PARPORT if SPARC64 && PCI
 	select ARCH_MIGHT_HAVE_PC_SERIO
-	select DMA_OPS
 	select OF
 	select OF_PROMTREE
 	select HAVE_ASM_MODVERSIONS
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 007bab9f2a0e39..9e2e7d361019fe 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -79,6 +79,7 @@ config X86
 	select ARCH_HAS_DEBUG_VIRTUAL
 	select ARCH_HAS_DEBUG_VM_PGTABLE	if !X86_PAE
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
+	select ARCH_HAS_DMA_OPS			if GART_IOMMU || XEN
 	select ARCH_HAS_EARLY_DEBUG		if KGDB
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_FAST_MULTIPLIER
@@ -943,7 +944,6 @@ config DMI
 
 config GART_IOMMU
 	bool "Old AMD GART IOMMU support"
-	select DMA_OPS
 	select IOMMU_HELPER
 	select SWIOTLB
 	depends on X86_64 && PCI && AMD_NB
diff --git a/drivers/macintosh/macio_asic.c b/drivers/macintosh/macio_asic.c
index 13626205530d36..bede200e32e8ff 100644
--- a/drivers/macintosh/macio_asic.c
+++ b/drivers/macintosh/macio_asic.c
@@ -387,7 +387,7 @@ static struct macio_dev * macio_add_one_device(struct macio_chip *chip,
 	dma_set_max_seg_size(&dev->ofdev.dev, 65536);
 	dma_set_seg_boundary(&dev->ofdev.dev, 0xffffffff);
 
-#if defined(CONFIG_PCI) && defined(CONFIG_DMA_OPS)
+#if defined(CONFIG_PCI) && defined(CONFIG_ARCH_HAS_DMA_OPS)
 	/* Set the DMA ops to the ones from the PCI device, this could be
 	 * fishy if we didn't know that on PowerMac it's always direct ops
 	 * or iommu ops that will work fine
@@ -396,7 +396,7 @@ static struct macio_dev * macio_add_one_device(struct macio_chip *chip,
 	 */
 	dev->ofdev.dev.archdata = chip->lbus.pdev->dev.archdata;
 	dev->ofdev.dev.dma_ops = chip->lbus.pdev->dev.dma_ops;
-#endif /* CONFIG_PCI && CONFIG_DMA_OPS */
+#endif /* CONFIG_PCI && CONFIG_ARCH_HAS_DMA_OPS */
 
 #ifdef DEBUG
 	printk("preparing mdev @%p, ofdev @%p, dev @%p, kobj @%p\n",
diff --git a/drivers/media/pci/intel/ipu6/Kconfig b/drivers/media/pci/intel/ipu6/Kconfig
index 40e20f0aa5ae5d..49e4fb696573f6 100644
--- a/drivers/media/pci/intel/ipu6/Kconfig
+++ b/drivers/media/pci/intel/ipu6/Kconfig
@@ -4,8 +4,13 @@ config VIDEO_INTEL_IPU6
 	depends on VIDEO_DEV
 	depends on X86 && X86_64 && HAS_DMA
 	depends on IPU_BRIDGE || !IPU_BRIDGE
+	#
+	# This driver incorrectly tries to override the dma_ops.  It should
+	# never have done that, but for now keep it working on architectures
+	# that use dma ops
+	#
+	depends on ARCH_HAS_DMA_OPS
 	select AUXILIARY_BUS
-	select DMA_OPS
 	select IOMMU_IOVA
 	select VIDEO_V4L2_SUBDEV_API
 	select MEDIA_CONTROLLER
diff --git a/drivers/vdpa/Kconfig b/drivers/vdpa/Kconfig
index b08de3b7706109..559fb9d3271fcc 100644
--- a/drivers/vdpa/Kconfig
+++ b/drivers/vdpa/Kconfig
@@ -35,7 +35,12 @@ config VDPA_SIM_BLOCK
 config VDPA_USER
 	tristate "VDUSE (vDPA Device in Userspace) support"
 	depends on EVENTFD && MMU && HAS_DMA
-	select DMA_OPS
+	#
+	# This driver incorrectly tries to override the dma_ops.  It should
+	# never have done that, but for now keep it working on architectures
+	# that use dma ops
+	#
+	depends on ARCH_HAS_DMA_OPS
 	select VHOST_IOTLB
 	select IOMMU_IOVA
 	help
diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
index d5989871dd5de3..27f288b5f30c37 100644
--- a/drivers/xen/Kconfig
+++ b/drivers/xen/Kconfig
@@ -177,8 +177,8 @@ config XEN_GRANT_DMA_ALLOC
 
 config SWIOTLB_XEN
 	def_bool y
+	depends on ARCH_DMA_OPS
 	depends on XEN_PV || ARM || ARM64
-	select DMA_OPS
 	select SWIOTLB
 
 config XEN_PCI_STUB
@@ -348,10 +348,10 @@ config XEN_GRANT_DMA_IOMMU
 
 config XEN_GRANT_DMA_OPS
 	bool
-	select DMA_OPS
 
 config XEN_VIRTIO
 	bool "Xen virtio support"
+	depends on ARCH_DMA_OPS
 	depends on VIRTIO
 	select XEN_GRANT_DMA_OPS
 	select XEN_GRANT_DMA_IOMMU if OF
diff --git a/include/linux/device.h b/include/linux/device.h
index 1c5280d28bc389..b4bde8d226979b 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -750,7 +750,7 @@ struct device {
 	struct dev_pin_info	*pins;
 #endif
 	struct dev_msi_info	msi;
-#ifdef CONFIG_DMA_OPS
+#ifdef CONFIG_ARCH_HAS_DMA_OPS
 	const struct dma_map_ops *dma_ops;
 #endif
 	u64		*dma_mask;	/* dma mask (if dma'able device) */
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 077b15c93bb8ff..9668ddf3696e71 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -75,7 +75,7 @@ struct dma_map_ops {
 	unsigned long (*get_merge_boundary)(struct device *dev);
 };
 
-#ifdef CONFIG_DMA_OPS
+#ifdef CONFIG_ARCH_HAS_DMA_OPS
 #include <asm/dma-mapping.h>
 
 static inline const struct dma_map_ops *get_dma_ops(struct device *dev)
@@ -90,7 +90,7 @@ static inline void set_dma_ops(struct device *dev,
 {
 	dev->dma_ops = dma_ops;
 }
-#else /* CONFIG_DMA_OPS */
+#else /* CONFIG_ARCH_HAS_DMA_OPS */
 static inline const struct dma_map_ops *get_dma_ops(struct device *dev)
 {
 	return NULL;
@@ -99,7 +99,7 @@ static inline void set_dma_ops(struct device *dev,
 			       const struct dma_map_ops *dma_ops)
 {
 }
-#endif /* CONFIG_DMA_OPS */
+#endif /* CONFIG_ARCH_HAS_DMA_OPS */
 
 #ifdef CONFIG_DMA_CMA
 extern struct cma *dma_contiguous_default_area;
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index 21bae17008368a..4c0dcd90912167 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -11,11 +11,6 @@ config HAS_DMA
 config DMA_OPS_HELPERS
 	bool
 
-config DMA_OPS
-	depends on HAS_DMA
-	select DMA_OPS_HELPERS
-	bool
-
 #
 # IOMMU drivers that can bypass the IOMMU code and optionally use the direct
 # mapping fast path should select this option and set the dma_ops_bypass
@@ -113,8 +108,8 @@ config DMA_BOUNCE_UNALIGNED_KMALLOC
 
 config DMA_NEED_SYNC
 	def_bool ARCH_HAS_SYNC_DMA_FOR_DEVICE || ARCH_HAS_SYNC_DMA_FOR_CPU || \
-		 ARCH_HAS_SYNC_DMA_FOR_CPU_ALL || DMA_API_DEBUG || DMA_OPS || \
-		 SWIOTLB
+		 ARCH_HAS_SYNC_DMA_FOR_CPU_ALL || DMA_API_DEBUG || \
+		 ARCH_HAS_DMA_OPS || SWIOTLB
 
 config DMA_RESTRICTED_POOL
 	bool "DMA Restricted Pool"
diff --git a/kernel/dma/Makefile b/kernel/dma/Makefile
index 2e6e933cf7f3fb..6977033444a375 100644
--- a/kernel/dma/Makefile
+++ b/kernel/dma/Makefile
@@ -2,7 +2,7 @@
 
 obj-$(CONFIG_HAS_DMA)			+= mapping.o direct.o
 obj-$(CONFIG_DMA_OPS_HELPERS)		+= ops_helpers.o
-obj-$(CONFIG_DMA_OPS)			+= dummy.o
+obj-$(CONFIG_ARCH_HAS_DMA_OPS)		+= dummy.o
 obj-$(CONFIG_DMA_CMA)			+= contiguous.o
 obj-$(CONFIG_DMA_DECLARE_COHERENT)	+= coherent.o
 obj-$(CONFIG_DMA_API_DEBUG)		+= debug.o
-- 
2.43.0

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