[PATCH v2 0/5] Clean up VMD DMA Map Ops

[PATCH v2 0/5] Clean up VMD DMA Map Ops

[Jon Derrick]

v1 Set: https://lore.kernel.org/linux-iommu/20200107134125.GD30750@8bytes.org/T/#t

This revision introduces a new weak function to reference the dma alias, as
well as using the struct device rather than the pci_dev. By using the weak
function in this manner, we remove the need to add a pointer in struct device
or pci_dev. Weak functions are generally frowned upon when it's a single
architecture implementation, so I am open to alternatives.

v1 Blurb:
VMD currently works with VT-d enabled by pointing DMA and IOMMU actions at the
VMD endpoint. The problem with this approach is that the VMD endpoint's
device-specific attributes, such as the dma mask, are used instead.

This set cleans up VMD by removing the override that redirects dma map
operations to the VMD endpoint. Instead it introduces a new dma alias mechanism
into the existing dma alias infrastructure.

Changes from v1:
Removed 1/5 & 2/5 misc fix patches that were merged
Uses Christoph's staging/cleanup patches
Introduce weak function rather than including pointer in struct device or pci_dev.

Based on Joerg's next:
https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git/

Christoph Hellwig (2):
  x86/pci: Add a to_pci_sysdata helper
  x86/pci: Replace the vmd_domain field with a vmd_dev pointer

Jon Derrick (3):
  PCI: Introduce direct dma alias
  PCI: vmd: Stop overriding dma_map_ops
  x86/pci: Remove X86_DEV_DMA_OPS

 arch/x86/Kconfig               |   3 -
 arch/x86/include/asm/device.h  |  10 ---
 arch/x86/include/asm/pci.h     |  31 ++++-----
 arch/x86/pci/common.c          |  45 ++----------
 drivers/iommu/intel-iommu.c    |  17 +++--
 drivers/pci/controller/Kconfig |   1 -
 drivers/pci/controller/vmd.c   | 152 +----------------------------------------
 drivers/pci/pci.c              |  17 ++++-
 drivers/pci/search.c           |   9 +++
 include/linux/pci.h            |   1 +
 10 files changed, 60 insertions(+), 226 deletions(-)

-- 
1.8.3.1

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[PATCH v2 1/5] x86/pci: Add a to_pci_sysdata helper

[Jon Derrick]

From: Christoph Hellwig <hch@lst.de>

From: Christoph Hellwig <hch@lst.de>

Various helpers need the pci_sysdata just to dereference a single field
in it.  Add a little helper that returns the properly typed sysdata
pointer to require a little less boilerplate code.

Signed-off-by: Christoph Hellwig <hch@lst.de>
[jonathan.derrick: added un-const cast]
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
---
 arch/x86/include/asm/pci.h | 28 +++++++++++++---------------
 1 file changed, 13 insertions(+), 15 deletions(-)

diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
index 90d0731..cf680c5 100644
--- a/arch/x86/include/asm/pci.h
+++ b/arch/x86/include/asm/pci.h
@@ -35,12 +35,15 @@ struct pci_sysdata {
 
 #ifdef CONFIG_PCI
 
+static inline struct pci_sysdata *to_pci_sysdata(struct pci_bus *bus)
+{
+	return bus->sysdata;
+}
+
 #ifdef CONFIG_PCI_DOMAINS
 static inline int pci_domain_nr(struct pci_bus *bus)
 {
-	struct pci_sysdata *sd = bus->sysdata;
-
-	return sd->domain;
+	return to_pci_sysdata(bus)->domain;
 }
 
 static inline int pci_proc_domain(struct pci_bus *bus)
@@ -52,23 +55,20 @@ static inline int pci_proc_domain(struct pci_bus *bus)
 #ifdef CONFIG_PCI_MSI_IRQ_DOMAIN
 static inline void *_pci_root_bus_fwnode(struct pci_bus *bus)
 {
-	struct pci_sysdata *sd = bus->sysdata;
-
-	return sd->fwnode;
+	return to_pci_sysdata(bus)->fwnode;
 }
 
 #define pci_root_bus_fwnode	_pci_root_bus_fwnode
 #endif
 
+#if IS_ENABLED(CONFIG_VMD)
 static inline bool is_vmd(struct pci_bus *bus)
 {
-#if IS_ENABLED(CONFIG_VMD)
-	struct pci_sysdata *sd = bus->sysdata;
-
-	return sd->vmd_domain;
+	return to_pci_sysdata(bus)->vmd_domain;
+}
 #else
-	return false;
-#endif
+#define is_vmd(bus)		false
+#endif /* CONFIG_VMD */
 }
 
 /* Can be used to override the logic in pci_scan_bus for skipping
@@ -124,9 +124,7 @@ static inline void early_quirks(void) { }
 /* Returns the node based on pci bus */
 static inline int __pcibus_to_node(const struct pci_bus *bus)
 {
-	const struct pci_sysdata *sd = bus->sysdata;
-
-	return sd->node;
+	return to_pci_sysdata((struct pci_bus *) bus)->node;
 }
 
 static inline const struct cpumask *
-- 
1.8.3.1

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[PATCH v2 2/5] x86/pci: Replace the vmd_domain field with a vmd_dev pointer

[Jon Derrick]

From: Christoph Hellwig <hch@lst.de>

From: Christoph Hellwig <hch@lst.de>

Store the actual VMD device in struct pci_sysdata, so that we can later
use it directly for DMA mappings.

Reviewed-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/include/asm/pci.h   | 5 ++---
 drivers/pci/controller/vmd.c | 2 +-
 2 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/pci.h b/arch/x86/include/asm/pci.h
index cf680c5..7c6c7d7 100644
--- a/arch/x86/include/asm/pci.h
+++ b/arch/x86/include/asm/pci.h
@@ -25,7 +25,7 @@ struct pci_sysdata {
 	void		*fwnode;	/* IRQ domain for MSI assignment */
 #endif
 #if IS_ENABLED(CONFIG_VMD)
-	bool vmd_domain;		/* True if in Intel VMD domain */
+	struct device	*vmd_dev;	/* Main device if in Intel VMD domain */
 #endif
 };
 
@@ -64,12 +64,11 @@ static inline void *_pci_root_bus_fwnode(struct pci_bus *bus)
 #if IS_ENABLED(CONFIG_VMD)
 static inline bool is_vmd(struct pci_bus *bus)
 {
-	return to_pci_sysdata(bus)->vmd_domain;
+	return to_pci_sysdata(bus)->vmd_dev != NULL;
 }
 #else
 #define is_vmd(bus)		false
 #endif /* CONFIG_VMD */
-}
 
 /* Can be used to override the logic in pci_scan_bus for skipping
    already-configured bus numbers - to be used for buggy BIOSes
diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 2128422..907b5bd 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -679,7 +679,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 		.parent = res,
 	};
 
-	sd->vmd_domain = true;
+	sd->vmd_dev = &vmd->dev->dev;
 	sd->domain = vmd_find_free_domain();
 	if (sd->domain < 0)
 		return sd->domain;
-- 
1.8.3.1

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[PATCH v2 3/5] PCI: Introduce direct dma alias

[Jon Derrick]

The current dma alias implementation requires the aliased device be on
the same bus as the dma parent. This introduces an arch-specific
mechanism to point to an arbitrary struct device when doing mapping and
pci alias search.

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
---
 arch/x86/pci/common.c |  7 +++++++
 drivers/pci/pci.c     | 17 ++++++++++++++++-
 drivers/pci/search.c  |  9 +++++++++
 include/linux/pci.h   |  1 +
 4 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 1e59df0..565cc17 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -736,3 +736,10 @@ int pci_ext_cfg_avail(void)
 	else
 		return 0;
 }
+
+#if IS_ENABLED(CONFIG_VMD)
+struct device *pci_direct_dma_alias(struct pci_dev *dev)
+{
+	return to_pci_sysdata(dev->bus)->vmd_dev;
+}
+#endif
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index ad746d9..e4269e9 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -6034,7 +6034,9 @@ bool pci_devs_are_dma_aliases(struct pci_dev *dev1, struct pci_dev *dev2)
 	return (dev1->dma_alias_mask &&
 		test_bit(dev2->devfn, dev1->dma_alias_mask)) ||
 	       (dev2->dma_alias_mask &&
-		test_bit(dev1->devfn, dev2->dma_alias_mask));
+		test_bit(dev1->devfn, dev2->dma_alias_mask)) ||
+	       (pci_direct_dma_alias(dev1) == &dev2->dev) ||
+	       (pci_direct_dma_alias(dev2) == &dev1->dev);
 }
 
 bool pci_device_is_present(struct pci_dev *pdev)
@@ -6058,6 +6060,19 @@ void pci_ignore_hotplug(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_ignore_hotplug);
 
+/**
+ * pci_direct_dma_alias - Get dma alias for pci device
+ * @dev: the PCI device that may have a dma alias
+ *
+ * Permits the platform to provide architecture-specific functionality to
+ * devices needing to alias dma to another device. This is the default
+ * implementation. Architecture implementations can override this.
+ */
+struct device __weak *pci_direct_dma_alias(struct pci_dev *dev)
+{
+	return NULL;
+}
+
 resource_size_t __weak pcibios_default_alignment(void)
 {
 	return 0;
diff --git a/drivers/pci/search.c b/drivers/pci/search.c
index bade140..6d61209 100644
--- a/drivers/pci/search.c
+++ b/drivers/pci/search.c
@@ -32,6 +32,15 @@ int pci_for_each_dma_alias(struct pci_dev *pdev,
 	struct pci_bus *bus;
 	int ret;
 
+	if (unlikely(pci_direct_dma_alias(pdev))) {
+		struct device *dev = pci_direct_dma_alias(pdev);
+
+		if (dev_is_pci(dev))
+			pdev = to_pci_dev(dev);
+		return fn(pdev, PCI_DEVID(pdev->bus->number, pdev->devfn),
+			  data);
+	}
+
 	ret = fn(pdev, pci_dev_id(pdev), data);
 	if (ret)
 		return ret;
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c393dff..82494d3 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1202,6 +1202,7 @@ u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev,
 int pci_select_bars(struct pci_dev *dev, unsigned long flags);
 bool pci_device_is_present(struct pci_dev *pdev);
 void pci_ignore_hotplug(struct pci_dev *dev);
+struct device *pci_direct_dma_alias(struct pci_dev *dev);
 
 int __printf(6, 7) pci_request_irq(struct pci_dev *dev, unsigned int nr,
 		irq_handler_t handler, irq_handler_t thread_fn, void *dev_id,
-- 
1.8.3.1

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[PATCH v2 4/5] PCI: vmd: Stop overriding dma_map_ops

[Jon Derrick]

Devices on the VMD domain use the VMD endpoint's requester-id and have
been relying on the VMD endpoint's dma operations. The downside of this
was that VMD domain devices would use the VMD endpoint's attributes when
doing DMA and IOMMU mapping. We can be smarter about this by only using
the VMD endpoint when mapping and providing the correct child device's
attributes during dma operations.

This patch modifies intel-iommu to check for a 'direct dma alias' and
refer to it for mapping.

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
---
 drivers/iommu/intel-iommu.c    |  17 +++--
 drivers/pci/controller/Kconfig |   1 -
 drivers/pci/controller/vmd.c   | 150 -----------------------------------------
 3 files changed, 12 insertions(+), 156 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index b2526a4..c812594 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -773,14 +773,13 @@ static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devf
 
 	if (dev_is_pci(dev)) {
 		struct pci_dev *pf_pdev;
+		struct device *dma_alias;
 
 		pdev = to_pci_dev(dev);
 
-#ifdef CONFIG_X86
-		/* VMD child devices currently cannot be handled individually */
-		if (is_vmd(pdev->bus))
-			return NULL;
-#endif
+		dma_alias = pci_direct_dma_alias(pdev);
+		if (dma_alias && dev_is_pci(dma_alias))
+			pdev = to_pci_dev(dma_alias);
 
 		/* VFs aren't listed in scope tables; we need to look up
 		 * the PF instead to find the IOMMU. */
@@ -2428,6 +2427,14 @@ static struct dmar_domain *find_domain(struct device *dev)
 		     dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO))
 		return NULL;
 
+	if (dev_is_pci(dev)) {
+		struct pci_dev *pdev = to_pci_dev(dev);
+		struct device *dma_alias = pci_direct_dma_alias(pdev);
+
+		if (dma_alias)
+			dev = dma_alias;
+	}
+
 	/* No lock here, assumes no domain exit in normal case */
 	info = dev->archdata.iommu;
 	if (likely(info))
diff --git a/drivers/pci/controller/Kconfig b/drivers/pci/controller/Kconfig
index c77069c..55671429 100644
--- a/drivers/pci/controller/Kconfig
+++ b/drivers/pci/controller/Kconfig
@@ -239,7 +239,6 @@ config PCIE_TANGO_SMP8759
 
 config VMD
 	depends on PCI_MSI && X86_64 && SRCU
-	select X86_DEV_DMA_OPS
 	tristate "Intel Volume Management Device Driver"
 	---help---
 	  Adds support for the Intel Volume Management Device (VMD). VMD is a
diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index 907b5bd..5824a39 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -98,9 +98,6 @@ struct vmd_dev {
 	struct irq_domain	*irq_domain;
 	struct pci_bus		*bus;
 	u8			busn_start;
-
-	struct dma_map_ops	dma_ops;
-	struct dma_domain	dma_domain;
 };
 
 static inline struct vmd_dev *vmd_from_bus(struct pci_bus *bus)
@@ -295,151 +292,6 @@ static void vmd_set_desc(msi_alloc_info_t *arg, struct msi_desc *desc)
 	.chip		= &vmd_msi_controller,
 };
 
-/*
- * VMD replaces the requester ID with its own.  DMA mappings for devices in a
- * VMD domain need to be mapped for the VMD, not the device requiring
- * the mapping.
- */
-static struct device *to_vmd_dev(struct device *dev)
-{
-	struct pci_dev *pdev = to_pci_dev(dev);
-	struct vmd_dev *vmd = vmd_from_bus(pdev->bus);
-
-	return &vmd->dev->dev;
-}
-
-static void *vmd_alloc(struct device *dev, size_t size, dma_addr_t *addr,
-		       gfp_t flag, unsigned long attrs)
-{
-	return dma_alloc_attrs(to_vmd_dev(dev), size, addr, flag, attrs);
-}
-
-static void vmd_free(struct device *dev, size_t size, void *vaddr,
-		     dma_addr_t addr, unsigned long attrs)
-{
-	return dma_free_attrs(to_vmd_dev(dev), size, vaddr, addr, attrs);
-}
-
-static int vmd_mmap(struct device *dev, struct vm_area_struct *vma,
-		    void *cpu_addr, dma_addr_t addr, size_t size,
-		    unsigned long attrs)
-{
-	return dma_mmap_attrs(to_vmd_dev(dev), vma, cpu_addr, addr, size,
-			attrs);
-}
-
-static int vmd_get_sgtable(struct device *dev, struct sg_table *sgt,
-			   void *cpu_addr, dma_addr_t addr, size_t size,
-			   unsigned long attrs)
-{
-	return dma_get_sgtable_attrs(to_vmd_dev(dev), sgt, cpu_addr, addr, size,
-			attrs);
-}
-
-static dma_addr_t vmd_map_page(struct device *dev, struct page *page,
-			       unsigned long offset, size_t size,
-			       enum dma_data_direction dir,
-			       unsigned long attrs)
-{
-	return dma_map_page_attrs(to_vmd_dev(dev), page, offset, size, dir,
-			attrs);
-}
-
-static void vmd_unmap_page(struct device *dev, dma_addr_t addr, size_t size,
-			   enum dma_data_direction dir, unsigned long attrs)
-{
-	dma_unmap_page_attrs(to_vmd_dev(dev), addr, size, dir, attrs);
-}
-
-static int vmd_map_sg(struct device *dev, struct scatterlist *sg, int nents,
-		      enum dma_data_direction dir, unsigned long attrs)
-{
-	return dma_map_sg_attrs(to_vmd_dev(dev), sg, nents, dir, attrs);
-}
-
-static void vmd_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
-			 enum dma_data_direction dir, unsigned long attrs)
-{
-	dma_unmap_sg_attrs(to_vmd_dev(dev), sg, nents, dir, attrs);
-}
-
-static void vmd_sync_single_for_cpu(struct device *dev, dma_addr_t addr,
-				    size_t size, enum dma_data_direction dir)
-{
-	dma_sync_single_for_cpu(to_vmd_dev(dev), addr, size, dir);
-}
-
-static void vmd_sync_single_for_device(struct device *dev, dma_addr_t addr,
-				       size_t size, enum dma_data_direction dir)
-{
-	dma_sync_single_for_device(to_vmd_dev(dev), addr, size, dir);
-}
-
-static void vmd_sync_sg_for_cpu(struct device *dev, struct scatterlist *sg,
-				int nents, enum dma_data_direction dir)
-{
-	dma_sync_sg_for_cpu(to_vmd_dev(dev), sg, nents, dir);
-}
-
-static void vmd_sync_sg_for_device(struct device *dev, struct scatterlist *sg,
-				   int nents, enum dma_data_direction dir)
-{
-	dma_sync_sg_for_device(to_vmd_dev(dev), sg, nents, dir);
-}
-
-static int vmd_dma_supported(struct device *dev, u64 mask)
-{
-	return dma_supported(to_vmd_dev(dev), mask);
-}
-
-static u64 vmd_get_required_mask(struct device *dev)
-{
-	return dma_get_required_mask(to_vmd_dev(dev));
-}
-
-static void vmd_teardown_dma_ops(struct vmd_dev *vmd)
-{
-	struct dma_domain *domain = &vmd->dma_domain;
-
-	if (get_dma_ops(&vmd->dev->dev))
-		del_dma_domain(domain);
-}
-
-#define ASSIGN_VMD_DMA_OPS(source, dest, fn)	\
-	do {					\
-		if (source->fn)			\
-			dest->fn = vmd_##fn;	\
-	} while (0)
-
-static void vmd_setup_dma_ops(struct vmd_dev *vmd)
-{
-	const struct dma_map_ops *source = get_dma_ops(&vmd->dev->dev);
-	struct dma_map_ops *dest = &vmd->dma_ops;
-	struct dma_domain *domain = &vmd->dma_domain;
-
-	domain->domain_nr = vmd->sysdata.domain;
-	domain->dma_ops = dest;
-
-	if (!source)
-		return;
-	ASSIGN_VMD_DMA_OPS(source, dest, alloc);
-	ASSIGN_VMD_DMA_OPS(source, dest, free);
-	ASSIGN_VMD_DMA_OPS(source, dest, mmap);
-	ASSIGN_VMD_DMA_OPS(source, dest, get_sgtable);
-	ASSIGN_VMD_DMA_OPS(source, dest, map_page);
-	ASSIGN_VMD_DMA_OPS(source, dest, unmap_page);
-	ASSIGN_VMD_DMA_OPS(source, dest, map_sg);
-	ASSIGN_VMD_DMA_OPS(source, dest, unmap_sg);
-	ASSIGN_VMD_DMA_OPS(source, dest, sync_single_for_cpu);
-	ASSIGN_VMD_DMA_OPS(source, dest, sync_single_for_device);
-	ASSIGN_VMD_DMA_OPS(source, dest, sync_sg_for_cpu);
-	ASSIGN_VMD_DMA_OPS(source, dest, sync_sg_for_device);
-	ASSIGN_VMD_DMA_OPS(source, dest, dma_supported);
-	ASSIGN_VMD_DMA_OPS(source, dest, get_required_mask);
-	add_dma_domain(domain);
-}
-#undef ASSIGN_VMD_DMA_OPS
-
 static char __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus *bus,
 				  unsigned int devfn, int reg, int len)
 {
@@ -709,7 +561,6 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	}
 
 	vmd_attach_resources(vmd);
-	vmd_setup_dma_ops(vmd);
 	dev_set_msi_domain(&vmd->bus->dev, vmd->irq_domain);
 
 	pci_scan_child_bus(vmd->bus);
@@ -824,7 +675,6 @@ static void vmd_remove(struct pci_dev *dev)
 	pci_stop_root_bus(vmd->bus);
 	pci_remove_root_bus(vmd->bus);
 	vmd_cleanup_srcu(vmd);
-	vmd_teardown_dma_ops(vmd);
 	vmd_detach_resources(vmd);
 	irq_domain_remove(vmd->irq_domain);
 }
-- 
1.8.3.1

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[PATCH v2 5/5] x86/pci: Remove X86_DEV_DMA_OPS

[Jon Derrick]

From: Christoph Hellwig <hch@lst.de>

There are no users of X86_DEV_DMA_OPS left, so remove the code.

Reviewed-by: Jon Derrick <jonathan.derrick@intel.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 arch/x86/Kconfig              |  3 ---
 arch/x86/include/asm/device.h | 10 ----------
 arch/x86/pci/common.c         | 38 --------------------------------------
 3 files changed, 51 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 5e89499..77f9426 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -2955,9 +2955,6 @@ config HAVE_ATOMIC_IOMAP
 	def_bool y
 	depends on X86_32
 
-config X86_DEV_DMA_OPS
-	bool
-
 source "drivers/firmware/Kconfig"
 
 source "arch/x86/kvm/Kconfig"
diff --git a/arch/x86/include/asm/device.h b/arch/x86/include/asm/device.h
index 5e12c63..7e31f7f 100644
--- a/arch/x86/include/asm/device.h
+++ b/arch/x86/include/asm/device.h
@@ -8,16 +8,6 @@ struct dev_archdata {
 #endif
 };
 
-#if defined(CONFIG_X86_DEV_DMA_OPS) && defined(CONFIG_PCI_DOMAINS)
-struct dma_domain {
-	struct list_head node;
-	const struct dma_map_ops *dma_ops;
-	int domain_nr;
-};
-void add_dma_domain(struct dma_domain *domain);
-void del_dma_domain(struct dma_domain *domain);
-#endif
-
 struct pdev_archdata {
 };
 
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 565cc17..5a9fb00 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -625,43 +625,6 @@ unsigned int pcibios_assign_all_busses(void)
 	return (pci_probe & PCI_ASSIGN_ALL_BUSSES) ? 1 : 0;
 }
 
-#if defined(CONFIG_X86_DEV_DMA_OPS) && defined(CONFIG_PCI_DOMAINS)
-static LIST_HEAD(dma_domain_list);
-static DEFINE_SPINLOCK(dma_domain_list_lock);
-
-void add_dma_domain(struct dma_domain *domain)
-{
-	spin_lock(&dma_domain_list_lock);
-	list_add(&domain->node, &dma_domain_list);
-	spin_unlock(&dma_domain_list_lock);
-}
-EXPORT_SYMBOL_GPL(add_dma_domain);
-
-void del_dma_domain(struct dma_domain *domain)
-{
-	spin_lock(&dma_domain_list_lock);
-	list_del(&domain->node);
-	spin_unlock(&dma_domain_list_lock);
-}
-EXPORT_SYMBOL_GPL(del_dma_domain);
-
-static void set_dma_domain_ops(struct pci_dev *pdev)
-{
-	struct dma_domain *domain;
-
-	spin_lock(&dma_domain_list_lock);
-	list_for_each_entry(domain, &dma_domain_list, node) {
-		if (pci_domain_nr(pdev->bus) == domain->domain_nr) {
-			pdev->dev.dma_ops = domain->dma_ops;
-			break;
-		}
-	}
-	spin_unlock(&dma_domain_list_lock);
-}
-#else
-static void set_dma_domain_ops(struct pci_dev *pdev) {}
-#endif
-
 static void set_dev_domain_options(struct pci_dev *pdev)
 {
 	if (is_vmd(pdev->bus))
@@ -697,7 +660,6 @@ int pcibios_add_device(struct pci_dev *dev)
 		pa_data = data->next;
 		memunmap(data);
 	}
-	set_dma_domain_ops(dev);
 	set_dev_domain_options(dev);
 	return 0;
 }
-- 
1.8.3.1

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Re: [PATCH v2 3/5] PCI: Introduce direct dma alias

[Bjorn Helgaas]

In subject:
s/Introduce direct dma alias/Add pci_direct_dma_alias()/

On Thu, Jan 09, 2020 at 07:30:54AM -0700, Jon Derrick wrote:
> The current dma alias implementation requires the aliased device be on
> the same bus as the dma parent. This introduces an arch-specific
> mechanism to point to an arbitrary struct device when doing mapping and
> pci alias search.

"arbitrary struct device" is a little weird since an arbitrary device
doesn't have to be a PCI device, but these mappings and aliases only
make sense in the PCI domain.

Maybe it has something to do with pci_sysdata.vmd_dev being a
"struct device *" rather than a "struct pci_dev *"?  I don't know why
that is, because it looks like every place you use it, you use
to_pci_dev() to get the pci_dev pointer back anyway.  But I assume you
have some good reason for that.

s/dma/DMA/
s/pci/PCI/
(above and also in code comments below)

> Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
> ---
>  arch/x86/pci/common.c |  7 +++++++
>  drivers/pci/pci.c     | 17 ++++++++++++++++-
>  drivers/pci/search.c  |  9 +++++++++
>  include/linux/pci.h   |  1 +
>  4 files changed, 33 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
> index 1e59df0..565cc17 100644
> --- a/arch/x86/pci/common.c
> +++ b/arch/x86/pci/common.c
> @@ -736,3 +736,10 @@ int pci_ext_cfg_avail(void)
>  	else
>  		return 0;
>  }
> +
> +#if IS_ENABLED(CONFIG_VMD)
> +struct device *pci_direct_dma_alias(struct pci_dev *dev)
> +{
> +	return to_pci_sysdata(dev->bus)->vmd_dev;
> +}
> +#endif
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index ad746d9..e4269e9 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -6034,7 +6034,9 @@ bool pci_devs_are_dma_aliases(struct pci_dev *dev1, struct pci_dev *dev2)
>  	return (dev1->dma_alias_mask &&
>  		test_bit(dev2->devfn, dev1->dma_alias_mask)) ||
>  	       (dev2->dma_alias_mask &&
> -		test_bit(dev1->devfn, dev2->dma_alias_mask));
> +		test_bit(dev1->devfn, dev2->dma_alias_mask)) ||
> +	       (pci_direct_dma_alias(dev1) == &dev2->dev) ||
> +	       (pci_direct_dma_alias(dev2) == &dev1->dev);
>  }
>  
>  bool pci_device_is_present(struct pci_dev *pdev)
> @@ -6058,6 +6060,19 @@ void pci_ignore_hotplug(struct pci_dev *dev)
>  }
>  EXPORT_SYMBOL_GPL(pci_ignore_hotplug);
>  
> +/**
> + * pci_direct_dma_alias - Get dma alias for pci device
> + * @dev: the PCI device that may have a dma alias
> + *
> + * Permits the platform to provide architecture-specific functionality to
> + * devices needing to alias dma to another device. This is the default
> + * implementation. Architecture implementations can override this.
> + */
> +struct device __weak *pci_direct_dma_alias(struct pci_dev *dev)
> +{
> +	return NULL;
> +}
> +
>  resource_size_t __weak pcibios_default_alignment(void)
>  {
>  	return 0;
> diff --git a/drivers/pci/search.c b/drivers/pci/search.c
> index bade140..6d61209 100644
> --- a/drivers/pci/search.c
> +++ b/drivers/pci/search.c
> @@ -32,6 +32,15 @@ int pci_for_each_dma_alias(struct pci_dev *pdev,
>  	struct pci_bus *bus;
>  	int ret;
>  
> +	if (unlikely(pci_direct_dma_alias(pdev))) {
> +		struct device *dev = pci_direct_dma_alias(pdev);
> +
> +		if (dev_is_pci(dev))
> +			pdev = to_pci_dev(dev);
> +		return fn(pdev, PCI_DEVID(pdev->bus->number, pdev->devfn),
> +			  data);
> +	}
> +
>  	ret = fn(pdev, pci_dev_id(pdev), data);
>  	if (ret)
>  		return ret;
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index c393dff..82494d3 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1202,6 +1202,7 @@ u32 pcie_bandwidth_available(struct pci_dev *dev, struct pci_dev **limiting_dev,
>  int pci_select_bars(struct pci_dev *dev, unsigned long flags);
>  bool pci_device_is_present(struct pci_dev *pdev);
>  void pci_ignore_hotplug(struct pci_dev *dev);
> +struct device *pci_direct_dma_alias(struct pci_dev *dev);
>  
>  int __printf(6, 7) pci_request_irq(struct pci_dev *dev, unsigned int nr,
>  		irq_handler_t handler, irq_handler_t thread_fn, void *dev_id,
> -- 
> 1.8.3.1
> 
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Re: [PATCH v2 3/5] PCI: Introduce direct dma alias

[Derrick, Jonathan]

On Thu, 2020-01-09 at 17:11 -0600, Bjorn Helgaas wrote:
> In subject:
> s/Introduce direct dma alias/Add pci_direct_dma_alias()/
> 
> On Thu, Jan 09, 2020 at 07:30:54AM -0700, Jon Derrick wrote:
> > The current dma alias implementation requires the aliased device be on
> > the same bus as the dma parent. This introduces an arch-specific
> > mechanism to point to an arbitrary struct device when doing mapping and
> > pci alias search.
> 
> "arbitrary struct device" is a little weird since an arbitrary device
> doesn't have to be a PCI device, but these mappings and aliases only
> make sense in the PCI domain.
> 
> Maybe it has something to do with pci_sysdata.vmd_dev being a
> "struct device *" rather than a "struct pci_dev *"?  I don't know why
> that is, because it looks like every place you use it, you use
> to_pci_dev() to get the pci_dev pointer back anyway.  But I assume you
> have some good reason for that.
No particular reason other than to align with the suggestion in the
last set to be using the struct device. It does make sense to reference
the struct device as that provides the dma context, however as you have
pointed out, the implementation here moreso needs the device's
pci_dev. 

I'll see how it looks for the next set.

> 
> s/dma/DMA/
> s/pci/PCI/
> (above and also in code comments below)
> 
> > 
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