[PATCH 00/18] Provide a new two step DMA mapping API

[PATCH 00/18] Provide a new two step DMA mapping API

[Leon Romanovsky]

Currently the only efficient way to map a complex memory description through
the DMA API is by using the scatterlist APIs. The SG APIs are unique in that
they efficiently combine the two fundamental operations of sizing and allocating
a large IOVA window from the IOMMU and processing all the per-address
swiotlb/flushing/p2p/map details.

This uniqueness has been a long standing pain point as the scatterlist API
is mandatory, but expensive to use. It prevents any kind of optimization or
feature improvement (such as avoiding struct page for P2P) due to the impossibility
of improving the scatterlist.

Several approaches have been explored to expand the DMA API with additional
scatterlist-like structures (BIO[1], rlist[2]), instead split up the DMA API
to allow callers to bring their own data structure.

The API is split up into parts:
 - Allocate IOVA space:
    To do any pre-allocation required. This is done based on the caller
    supplying some details about how much IOMMU address space it would need
    in worst case.
 - Map and unmap relevant structures to pre-allocated IOVA space:
    Perform the actual mapping into the pre-allocated IOVA. This is very
    similar to dma_map_page().

In this and the next series [1], examples of three different users are converted
to the new API to show the benefits and its versatility. Each user has a unique
flow:
 1. RDMA ODP is an example of "SVA mirroring" using HMM that needs to
    dynamically map/unmap large numbers of single pages. This becomes
    significantly faster in the IOMMU case as the map/unmap is now just
    a page table walk, the IOVA allocation is pre-computed once. Significant
    amounts of memory are saved as there is no longer a need to store the
    dma_addr_t of each page.
 2. VFIO PCI live migration code is building a very large "page list"
    for the device. Instead of allocating a scatter list entry per allocated
    page it can just allocate an array of 'struct page *', saving a large
    amount of memory.
 3. NVMe PCI demonstrates how a BIO can be converted to a HW scatter
    list without having to allocate then populate an intermediate SG table.

To make the use of the new API easier, HMM and block subsystems are extended
to hide the optimization details from the caller. Among these optimizations:
 * Memory reduction as in most real use cases there is no need to store mapped
   DMA addresses and unmap them.
 * Reducing the function call overhead by removing the need to call function
   pointers and use direct calls instead.

This step is first along a path to provide alternatives to scatterlist and
solve some of the abuses and design mistakes, for instance in DMABUF's P2P
support.

Thanks

[1] https://lore.kernel.org/all/cover.1730037261.git.leon@kernel.org

Christoph Hellwig (6):
  PCI/P2PDMA: refactor the p2pdma mapping helpers
  dma-mapping: move the PCI P2PDMA mapping helpers to pci-p2pdma.h
  iommu: generalize the batched sync after map interface
  iommu/dma: Factor out a iommu_dma_map_swiotlb helper
  dma-mapping: add a dma_need_unmap helper
  docs: core-api: document the IOVA-based API

Leon Romanovsky (12):
  dma-mapping: Add check if IOVA can be used
  dma: Provide an interface to allow allocate IOVA
  dma-mapping: Implement link/unlink ranges API
  mm/hmm: let users to tag specific PFN with DMA mapped bit
  mm/hmm: provide generic DMA managing logic
  RDMA/umem: Store ODP access mask information in PFN
  RDMA/core: Convert UMEM ODP DMA mapping to caching IOVA and page
    linkage
  RDMA/umem: Separate implicit ODP initialization from explicit ODP
  vfio/mlx5: Explicitly use number of pages instead of allocated length
  vfio/mlx5: Rewrite create mkey flow to allow better code reuse
  vfio/mlx5: Explicitly store page list
  vfio/mlx5: Convert vfio to use DMA link API

 Documentation/core-api/dma-api.rst   |  70 +++++
 drivers/infiniband/core/umem_odp.c   | 250 +++++----------
 drivers/infiniband/hw/mlx5/mlx5_ib.h |  12 +-
 drivers/infiniband/hw/mlx5/odp.c     |  65 ++--
 drivers/infiniband/hw/mlx5/umr.c     |  12 +-
 drivers/iommu/dma-iommu.c            | 455 +++++++++++++++++++++++----
 drivers/iommu/iommu.c                |  65 ++--
 drivers/pci/p2pdma.c                 |  38 +--
 drivers/vfio/pci/mlx5/cmd.c          | 312 +++++++++---------
 drivers/vfio/pci/mlx5/cmd.h          |  24 +-
 drivers/vfio/pci/mlx5/main.c         |  87 +++--
 include/linux/dma-map-ops.h          |  54 ----
 include/linux/dma-mapping.h          |  84 +++++
 include/linux/hmm-dma.h              |  32 ++
 include/linux/hmm.h                  |  16 +
 include/linux/iommu.h                |   4 +
 include/linux/pci-p2pdma.h           |  84 +++++
 include/rdma/ib_umem_odp.h           |  25 +-
 kernel/dma/direct.c                  |  43 ++-
 kernel/dma/mapping.c                 |  20 ++
 mm/hmm.c                             | 229 +++++++++++++-
 21 files changed, 1345 insertions(+), 636 deletions(-)
 create mode 100644 include/linux/hmm-dma.h

-- 
2.46.2

[PATCH 01/18] PCI/P2PDMA: refactor the p2pdma mapping helpers

[Leon Romanovsky]

From: Christoph Hellwig <hch@lst.de>

The current scheme with a single helper to determine the P2P status
and map a scatterlist segment force users to always use the map_sg
helper to DMA map, which we're trying to get away from because they
are very cache inefficient.

Refactor the code so that there is a single helper that checks the P2P
state for a page, including the result that it is not a P2P page to
simplify the callers, and a second one to perform the address translation
for a bus mapped P2P transfer that does not depend on the scatterlist
structure.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/iommu/dma-iommu.c   | 46 ++++++++++++++++-----------------
 drivers/pci/p2pdma.c        | 38 ++++-----------------------
 include/linux/dma-map-ops.h | 51 +++++++++++++++++++++++++++++--------
 kernel/dma/direct.c         | 42 +++++++++++++++---------------
 4 files changed, 89 insertions(+), 88 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 2a9fa0c8cc00..6e50023c8112 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1382,7 +1382,6 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 	struct scatterlist *s, *prev = NULL;
 	int prot = dma_info_to_prot(dir, dev_is_dma_coherent(dev), attrs);
 	struct pci_p2pdma_map_state p2pdma_state = {};
-	enum pci_p2pdma_map_type map;
 	dma_addr_t iova;
 	size_t iova_len = 0;
 	unsigned long mask = dma_get_seg_boundary(dev);
@@ -1412,28 +1411,29 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
 		size_t s_length = s->length;
 		size_t pad_len = (mask - iova_len + 1) & mask;
 
-		if (is_pci_p2pdma_page(sg_page(s))) {
-			map = pci_p2pdma_map_segment(&p2pdma_state, dev, s);
-			switch (map) {
-			case PCI_P2PDMA_MAP_BUS_ADDR:
-				/*
-				 * iommu_map_sg() will skip this segment as
-				 * it is marked as a bus address,
-				 * __finalise_sg() will copy the dma address
-				 * into the output segment.
-				 */
-				continue;
-			case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
-				/*
-				 * Mapping through host bridge should be
-				 * mapped with regular IOVAs, thus we
-				 * do nothing here and continue below.
-				 */
-				break;
-			default:
-				ret = -EREMOTEIO;
-				goto out_restore_sg;
-			}
+		switch (pci_p2pdma_state(&p2pdma_state, dev, sg_page(s))) {
+		case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
+			/*
+			 * Mapping through host bridge should be mapped with
+			 * regular IOVAs, thus we do nothing here and continue
+			 * below.
+			 */
+		case PCI_P2PDMA_MAP_NONE:
+			break;
+		case PCI_P2PDMA_MAP_BUS_ADDR:
+			/*
+			 * iommu_map_sg() will skip this segment as it is marked
+			 * as a bus address, __finalise_sg() will copy the dma
+			 * address into the output segment.
+			 */
+			s->dma_address = pci_p2pdma_bus_addr_map(&p2pdma_state,
+						sg_phys(s));
+			sg_dma_len(s) = sg->length;
+			sg_dma_mark_bus_address(s);
+			continue;
+		default:
+			ret = -EREMOTEIO;
+			goto out_restore_sg;
 		}
 
 		sg_dma_address(s) = s_iova_off;
diff --git a/drivers/pci/p2pdma.c b/drivers/pci/p2pdma.c
index 4f47a13cb500..f38d16d71dd5 100644
--- a/drivers/pci/p2pdma.c
+++ b/drivers/pci/p2pdma.c
@@ -995,40 +995,12 @@ static enum pci_p2pdma_map_type pci_p2pdma_map_type(struct dev_pagemap *pgmap,
 	return type;
 }
 
-/**
- * pci_p2pdma_map_segment - map an sg segment determining the mapping type
- * @state: State structure that should be declared outside of the for_each_sg()
- *	loop and initialized to zero.
- * @dev: DMA device that's doing the mapping operation
- * @sg: scatterlist segment to map
- *
- * This is a helper to be used by non-IOMMU dma_map_sg() implementations where
- * the sg segment is the same for the page_link and the dma_address.
- *
- * Attempt to map a single segment in an SGL with the PCI bus address.
- * The segment must point to a PCI P2PDMA page and thus must be
- * wrapped in a is_pci_p2pdma_page(sg_page(sg)) check.
- *
- * Returns the type of mapping used and maps the page if the type is
- * PCI_P2PDMA_MAP_BUS_ADDR.
- */
-enum pci_p2pdma_map_type
-pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev,
-		       struct scatterlist *sg)
+void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
+		struct device *dev, struct page *page)
 {
-	if (state->pgmap != sg_page(sg)->pgmap) {
-		state->pgmap = sg_page(sg)->pgmap;
-		state->map = pci_p2pdma_map_type(state->pgmap, dev);
-		state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset;
-	}
-
-	if (state->map == PCI_P2PDMA_MAP_BUS_ADDR) {
-		sg->dma_address = sg_phys(sg) + state->bus_off;
-		sg_dma_len(sg) = sg->length;
-		sg_dma_mark_bus_address(sg);
-	}
-
-	return state->map;
+	state->pgmap = page->pgmap;
+	state->map = pci_p2pdma_map_type(state->pgmap, dev);
+	state->bus_off = to_p2p_pgmap(state->pgmap)->bus_offset;
 }
 
 /**
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index b7773201414c..49edcbda19d1 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -443,6 +443,11 @@ enum pci_p2pdma_map_type {
 	 */
 	PCI_P2PDMA_MAP_UNKNOWN = 0,
 
+	/*
+	 * Not a PCI P2PDMA transfer.
+	 */
+	PCI_P2PDMA_MAP_NONE,
+
 	/*
 	 * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will
 	 * traverse the host bridge and the host bridge is not in the
@@ -471,21 +476,47 @@ enum pci_p2pdma_map_type {
 
 struct pci_p2pdma_map_state {
 	struct dev_pagemap *pgmap;
-	int map;
+	enum pci_p2pdma_map_type map;
 	u64 bus_off;
 };
 
-#ifdef CONFIG_PCI_P2PDMA
-enum pci_p2pdma_map_type
-pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev,
-		       struct scatterlist *sg);
-#else /* CONFIG_PCI_P2PDMA */
+/* helper for pci_p2pdma_state(), do not use directly */
+void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
+		struct device *dev, struct page *page);
+
+/**
+ * pci_p2pdma_state - check the P2P transfer state of a page
+ * @state: 	P2P state structure
+ * @dev:	device to transfer to/from
+ * @page:	page to map
+ *
+ * Check if @page is a PCI P2PDMA page, and if yes of what kind.  Returns the
+ * map type, and updates @state with all information needed for a P2P transfer.
+ */
 static inline enum pci_p2pdma_map_type
-pci_p2pdma_map_segment(struct pci_p2pdma_map_state *state, struct device *dev,
-		       struct scatterlist *sg)
+pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev,
+		struct page *page)
+{
+	if (IS_ENABLED(CONFIG_PCI_P2PDMA) && is_pci_p2pdma_page(page)) {
+		if (state->pgmap != page->pgmap)
+			__pci_p2pdma_update_state(state, dev, page);
+		return state->map;
+	}
+	return PCI_P2PDMA_MAP_NONE;
+}
+
+/**
+ * pci_p2pdma_bus_addr_map - map a PCI_P2PDMA_MAP_BUS_ADDR P2P transfer
+ * @state: 	P2P state structure
+ * @paddr:	physical address to map
+ *
+ * Map a physically contigous PCI_P2PDMA_MAP_BUS_ADDR transfer.
+ */
+static inline dma_addr_t
+pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr)
 {
-	return PCI_P2PDMA_MAP_NOT_SUPPORTED;
+	WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR);
+	return paddr + state->bus_off;
 }
-#endif /* CONFIG_PCI_P2PDMA */
 
 #endif /* _LINUX_DMA_MAP_OPS_H */
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 5b4e6d3bf7bc..a793400161c2 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -462,34 +462,32 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
 		enum dma_data_direction dir, unsigned long attrs)
 {
 	struct pci_p2pdma_map_state p2pdma_state = {};
-	enum pci_p2pdma_map_type map;
 	struct scatterlist *sg;
 	int i, ret;
 
 	for_each_sg(sgl, sg, nents, i) {
-		if (is_pci_p2pdma_page(sg_page(sg))) {
-			map = pci_p2pdma_map_segment(&p2pdma_state, dev, sg);
-			switch (map) {
-			case PCI_P2PDMA_MAP_BUS_ADDR:
-				continue;
-			case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
-				/*
-				 * Any P2P mapping that traverses the PCI
-				 * host bridge must be mapped with CPU physical
-				 * address and not PCI bus addresses. This is
-				 * done with dma_direct_map_page() below.
-				 */
-				break;
-			default:
-				ret = -EREMOTEIO;
+		switch (pci_p2pdma_state(&p2pdma_state, dev, sg_page(sg))) {
+		case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
+			/*
+			 * Any P2P mapping that traverses the PCI host bridge
+			 * must be mapped with CPU physical address and not PCI
+			 * bus addresses.
+			 */
+		case PCI_P2PDMA_MAP_NONE:
+			sg->dma_address = dma_direct_map_page(dev, sg_page(sg),
+					sg->offset, sg->length, dir, attrs);
+			if (sg->dma_address == DMA_MAPPING_ERROR) {
+				ret = -EIO;
 				goto out_unmap;
 			}
-		}
-
-		sg->dma_address = dma_direct_map_page(dev, sg_page(sg),
-				sg->offset, sg->length, dir, attrs);
-		if (sg->dma_address == DMA_MAPPING_ERROR) {
-			ret = -EIO;
+			break;
+		case PCI_P2PDMA_MAP_BUS_ADDR:
+			sg->dma_address = pci_p2pdma_bus_addr_map(&p2pdma_state,
+					sg_phys(sg));
+			sg_dma_mark_bus_address(sg);
+			continue;
+		default:
+			ret = -EREMOTEIO;
 			goto out_unmap;
 		}
 		sg_dma_len(sg) = sg->length;
-- 
2.46.2

[PATCH 02/18] dma-mapping: move the PCI P2PDMA mapping helpers to pci-p2pdma.h

[Leon Romanovsky]

From: Christoph Hellwig <hch@lst.de>

To support the upcoming non-scatterlist mapping helpers, we need to go
back to have them called outside of the DMA API.  Thus move them out of
dma-map-ops.h, which is only for DMA API implementations to pci-p2pdma.h,
which is for driver use.

Note that the core helper is still not exported as the mapping is
expected to be done only by very highlevel subsystem code at least for
now.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/iommu/dma-iommu.c   |  1 +
 include/linux/dma-map-ops.h | 84 -------------------------------------
 include/linux/pci-p2pdma.h  | 84 +++++++++++++++++++++++++++++++++++++
 kernel/dma/direct.c         |  1 +
 4 files changed, 86 insertions(+), 84 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 6e50023c8112..c422e36c0d66 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -26,6 +26,7 @@
 #include <linux/mutex.h>
 #include <linux/of_iommu.h>
 #include <linux/pci.h>
+#include <linux/pci-p2pdma.h>
 #include <linux/scatterlist.h>
 #include <linux/spinlock.h>
 #include <linux/swiotlb.h>
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 49edcbda19d1..6ee626e50708 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -435,88 +435,4 @@ static inline void debug_dma_dump_mappings(struct device *dev)
 
 extern const struct dma_map_ops dma_dummy_ops;
 
-enum pci_p2pdma_map_type {
-	/*
-	 * PCI_P2PDMA_MAP_UNKNOWN: Used internally for indicating the mapping
-	 * type hasn't been calculated yet. Functions that return this enum
-	 * never return this value.
-	 */
-	PCI_P2PDMA_MAP_UNKNOWN = 0,
-
-	/*
-	 * Not a PCI P2PDMA transfer.
-	 */
-	PCI_P2PDMA_MAP_NONE,
-
-	/*
-	 * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will
-	 * traverse the host bridge and the host bridge is not in the
-	 * allowlist. DMA Mapping routines should return an error when
-	 * this is returned.
-	 */
-	PCI_P2PDMA_MAP_NOT_SUPPORTED,
-
-	/*
-	 * PCI_P2PDMA_BUS_ADDR: Indicates that two devices can talk to
-	 * each other directly through a PCI switch and the transaction will
-	 * not traverse the host bridge. Such a mapping should program
-	 * the DMA engine with PCI bus addresses.
-	 */
-	PCI_P2PDMA_MAP_BUS_ADDR,
-
-	/*
-	 * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: Indicates two devices can talk
-	 * to each other, but the transaction traverses a host bridge on the
-	 * allowlist. In this case, a normal mapping either with CPU physical
-	 * addresses (in the case of dma-direct) or IOVA addresses (in the
-	 * case of IOMMUs) should be used to program the DMA engine.
-	 */
-	PCI_P2PDMA_MAP_THRU_HOST_BRIDGE,
-};
-
-struct pci_p2pdma_map_state {
-	struct dev_pagemap *pgmap;
-	enum pci_p2pdma_map_type map;
-	u64 bus_off;
-};
-
-/* helper for pci_p2pdma_state(), do not use directly */
-void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
-		struct device *dev, struct page *page);
-
-/**
- * pci_p2pdma_state - check the P2P transfer state of a page
- * @state: 	P2P state structure
- * @dev:	device to transfer to/from
- * @page:	page to map
- *
- * Check if @page is a PCI P2PDMA page, and if yes of what kind.  Returns the
- * map type, and updates @state with all information needed for a P2P transfer.
- */
-static inline enum pci_p2pdma_map_type
-pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev,
-		struct page *page)
-{
-	if (IS_ENABLED(CONFIG_PCI_P2PDMA) && is_pci_p2pdma_page(page)) {
-		if (state->pgmap != page->pgmap)
-			__pci_p2pdma_update_state(state, dev, page);
-		return state->map;
-	}
-	return PCI_P2PDMA_MAP_NONE;
-}
-
-/**
- * pci_p2pdma_bus_addr_map - map a PCI_P2PDMA_MAP_BUS_ADDR P2P transfer
- * @state: 	P2P state structure
- * @paddr:	physical address to map
- *
- * Map a physically contigous PCI_P2PDMA_MAP_BUS_ADDR transfer.
- */
-static inline dma_addr_t
-pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr)
-{
-	WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR);
-	return paddr + state->bus_off;
-}
-
 #endif /* _LINUX_DMA_MAP_OPS_H */
diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
index 2c07aa6b7665..66b71f60a811 100644
--- a/include/linux/pci-p2pdma.h
+++ b/include/linux/pci-p2pdma.h
@@ -104,4 +104,88 @@ static inline struct pci_dev *pci_p2pmem_find(struct device *client)
 	return pci_p2pmem_find_many(&client, 1);
 }
 
+enum pci_p2pdma_map_type {
+	/*
+	 * PCI_P2PDMA_MAP_UNKNOWN: Used internally for indicating the mapping
+	 * type hasn't been calculated yet. Functions that return this enum
+	 * never return this value.
+	 */
+	PCI_P2PDMA_MAP_UNKNOWN = 0,
+
+	/*
+	 * Not a PCI P2PDMA transfer.
+	 */
+	PCI_P2PDMA_MAP_NONE,
+
+	/*
+	 * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will
+	 * traverse the host bridge and the host bridge is not in the
+	 * allowlist. DMA Mapping routines should return an error when
+	 * this is returned.
+	 */
+	PCI_P2PDMA_MAP_NOT_SUPPORTED,
+
+	/*
+	 * PCI_P2PDMA_BUS_ADDR: Indicates that two devices can talk to
+	 * each other directly through a PCI switch and the transaction will
+	 * not traverse the host bridge. Such a mapping should program
+	 * the DMA engine with PCI bus addresses.
+	 */
+	PCI_P2PDMA_MAP_BUS_ADDR,
+
+	/*
+	 * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: Indicates two devices can talk
+	 * to each other, but the transaction traverses a host bridge on the
+	 * allowlist. In this case, a normal mapping either with CPU physical
+	 * addresses (in the case of dma-direct) or IOVA addresses (in the
+	 * case of IOMMUs) should be used to program the DMA engine.
+	 */
+	PCI_P2PDMA_MAP_THRU_HOST_BRIDGE,
+};
+
+struct pci_p2pdma_map_state {
+	struct dev_pagemap *pgmap;
+	enum pci_p2pdma_map_type map;
+	u64 bus_off;
+};
+
+/* helper for pci_p2pdma_state(), do not use directly */
+void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
+		struct device *dev, struct page *page);
+
+/**
+ * pci_p2pdma_state - check the P2P transfer state of a page
+ * @state: 	P2P state structure
+ * @dev:	device to transfer to/from
+ * @page:	page to map
+ *
+ * Check if @page is a PCI P2PDMA page, and if yes of what kind.  Returns the
+ * map type, and updates @state with all information needed for a P2P transfer.
+ */
+static inline enum pci_p2pdma_map_type
+pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev,
+		struct page *page)
+{
+	if (IS_ENABLED(CONFIG_PCI_P2PDMA) && is_pci_p2pdma_page(page)) {
+		if (state->pgmap != page->pgmap)
+			__pci_p2pdma_update_state(state, dev, page);
+		return state->map;
+	}
+	return PCI_P2PDMA_MAP_NONE;
+}
+
+/**
+ * pci_p2pdma_bus_addr_map - map a PCI_P2PDMA_MAP_BUS_ADDR P2P transfer
+ * @state: 	P2P state structure
+ * @paddr:	physical address to map
+ *
+ * Map a physically contigous PCI_P2PDMA_MAP_BUS_ADDR transfer.
+ */
+static inline dma_addr_t
+pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr)
+{
+	WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR);
+	return paddr + state->bus_off;
+}
+
 #endif /* _LINUX_PCI_P2P_H */
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index a793400161c2..47e124561fff 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -13,6 +13,7 @@
 #include <linux/vmalloc.h>
 #include <linux/set_memory.h>
 #include <linux/slab.h>
+#include <linux/pci-p2pdma.h>
 #include "direct.h"
 
 /*
-- 
2.46.2

[PATCH 03/18] iommu: generalize the batched sync after map interface

[Leon Romanovsky]

From: Christoph Hellwig <hch@lst.de>

For the upcoming IOVA-based DMA API we want to use the interface batch the
sync after mapping multiple entries from dma-iommu without having a
scatterlist.

For that move more sanity checks from the callers into __iommu_map and
make that function available outside of iommu.c as iommu_map_nosync.

Add a wrapper for the map_sync as iommu_sync_map so that callers don't
need to poke into the methods directly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/iommu/iommu.c | 65 +++++++++++++++++++------------------------
 include/linux/iommu.h |  4 +++
 2 files changed, 33 insertions(+), 36 deletions(-)

diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 83c8e617a2c5..6b0943397e1e 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -2439,8 +2439,8 @@ static size_t iommu_pgsize(struct iommu_domain *domain, unsigned long iova,
 	return pgsize;
 }
 
-static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
-		       phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
+int iommu_map_nosync(struct iommu_domain *domain, unsigned long iova,
+		phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
 {
 	const struct iommu_domain_ops *ops = domain->ops;
 	unsigned long orig_iova = iova;
@@ -2449,12 +2449,19 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
 	phys_addr_t orig_paddr = paddr;
 	int ret = 0;
 
+	might_sleep_if(gfpflags_allow_blocking(gfp));
+
 	if (unlikely(!(domain->type & __IOMMU_DOMAIN_PAGING)))
 		return -EINVAL;
 
 	if (WARN_ON(!ops->map_pages || domain->pgsize_bitmap == 0UL))
 		return -ENODEV;
 
+	/* Discourage passing strange GFP flags */
+	if (WARN_ON_ONCE(gfp & (__GFP_COMP | __GFP_DMA | __GFP_DMA32 |
+				__GFP_HIGHMEM)))
+		return -EINVAL;
+
 	/* find out the minimum page size supported */
 	min_pagesz = 1 << __ffs(domain->pgsize_bitmap);
 
@@ -2502,31 +2509,27 @@ static int __iommu_map(struct iommu_domain *domain, unsigned long iova,
 	return ret;
 }
 
-int iommu_map(struct iommu_domain *domain, unsigned long iova,
-	      phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
+int iommu_sync_map(struct iommu_domain *domain, unsigned long iova, size_t size)
 {
 	const struct iommu_domain_ops *ops = domain->ops;
-	int ret;
-
-	might_sleep_if(gfpflags_allow_blocking(gfp));
 
-	/* Discourage passing strange GFP flags */
-	if (WARN_ON_ONCE(gfp & (__GFP_COMP | __GFP_DMA | __GFP_DMA32 |
-				__GFP_HIGHMEM)))
-		return -EINVAL;
+	if (!ops->iotlb_sync_map)
+		return 0;
+	return ops->iotlb_sync_map(domain, iova, size);
+}
 
-	ret = __iommu_map(domain, iova, paddr, size, prot, gfp);
-	if (ret == 0 && ops->iotlb_sync_map) {
-		ret = ops->iotlb_sync_map(domain, iova, size);
-		if (ret)
-			goto out_err;
-	}
+int iommu_map(struct iommu_domain *domain, unsigned long iova,
+	      phys_addr_t paddr, size_t size, int prot, gfp_t gfp)
+{
+	int ret;
 
-	return ret;
+	ret = iommu_map_nosync(domain, iova, paddr, size, prot, gfp);
+	if (ret)
+		return ret;
 
-out_err:
-	/* undo mappings already done */
-	iommu_unmap(domain, iova, size);
+	ret = iommu_sync_map(domain, iova, size);
+	if (ret)
+		iommu_unmap(domain, iova, size);
 
 	return ret;
 }
@@ -2612,26 +2615,17 @@ ssize_t iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
 		     struct scatterlist *sg, unsigned int nents, int prot,
 		     gfp_t gfp)
 {
-	const struct iommu_domain_ops *ops = domain->ops;
 	size_t len = 0, mapped = 0;
 	phys_addr_t start;
 	unsigned int i = 0;
 	int ret;
 
-	might_sleep_if(gfpflags_allow_blocking(gfp));
-
-	/* Discourage passing strange GFP flags */
-	if (WARN_ON_ONCE(gfp & (__GFP_COMP | __GFP_DMA | __GFP_DMA32 |
-				__GFP_HIGHMEM)))
-		return -EINVAL;
-
 	while (i <= nents) {
 		phys_addr_t s_phys = sg_phys(sg);
 
 		if (len && s_phys != start + len) {
-			ret = __iommu_map(domain, iova + mapped, start,
+			ret = iommu_map_nosync(domain, iova + mapped, start,
 					len, prot, gfp);
-
 			if (ret)
 				goto out_err;
 
@@ -2654,11 +2648,10 @@ ssize_t iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
 			sg = sg_next(sg);
 	}
 
-	if (ops->iotlb_sync_map) {
-		ret = ops->iotlb_sync_map(domain, iova, mapped);
-		if (ret)
-			goto out_err;
-	}
+	ret = iommu_sync_map(domain, iova, mapped);
+	if (ret)
+		goto out_err;
+
 	return mapped;
 
 out_err:
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index bd722f473635..8927e5f996c2 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -799,6 +799,10 @@ extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
 extern struct iommu_domain *iommu_get_dma_domain(struct device *dev);
 extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
 		     phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
+int iommu_map_nosync(struct iommu_domain *domain, unsigned long iova,
+		phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
+int iommu_sync_map(struct iommu_domain *domain, unsigned long iova,
+		size_t size);
 extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
 			  size_t size);
 extern size_t iommu_unmap_fast(struct iommu_domain *domain,
-- 
2.46.2

[PATCH 04/18] dma-mapping: Add check if IOVA can be used

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

This patch adds a check if IOVA can be used for the specific
transaction.

In the new API a DMA mapping transaction is identified by a
struct dma_iova_state, which holds some recomputed information
for the transaction which does not change for each page being
mapped.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 include/linux/dma-mapping.h | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 1524da363734..6075e0708deb 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -76,6 +76,20 @@
 
 #define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
 
+struct dma_iova_state {
+	size_t __size;
+};
+
+/*
+ * Use the high bit to mark if we used swiotlb for one or more ranges.
+ */
+#define DMA_IOVA_USE_SWIOTLB		(1ULL << 63)
+
+static inline size_t dma_iova_size(struct dma_iova_state *state)
+{
+	return state->__size & ~DMA_IOVA_USE_SWIOTLB;
+}
+
 #ifdef CONFIG_DMA_API_DEBUG
 void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr);
 void debug_dma_map_single(struct device *dev, const void *addr,
@@ -281,6 +295,25 @@ static inline int dma_mmap_noncontiguous(struct device *dev,
 }
 #endif /* CONFIG_HAS_DMA */
 
+#ifdef CONFIG_IOMMU_DMA
+/**
+ * dma_use_iova - check if the IOVA API is used for this state
+ * @state: IOVA state
+ *
+ * Return %true if the DMA transfers uses the dma_iova_*() calls or %false if
+ * they can't be used.
+ */
+static inline bool dma_use_iova(struct dma_iova_state *state)
+{
+	return state->__size != 0;
+}
+#else /* CONFIG_IOMMU_DMA */
+static inline bool dma_use_iova(struct dma_iova_state *state)
+{
+	return false;
+}
+#endif /* CONFIG_IOMMU_DMA */
+
 #if defined(CONFIG_HAS_DMA) && defined(CONFIG_DMA_NEED_SYNC)
 void __dma_sync_single_for_cpu(struct device *dev, dma_addr_t addr, size_t size,
 		enum dma_data_direction dir);
-- 
2.46.2

[PATCH 05/18] dma: Provide an interface to allow allocate IOVA

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

The existing .map_page() callback provides both allocating of IOVA
and linking DMA pages. That combination works great for most of the
callers who use it in control paths, but is less effective in fast
paths where there may be multiple calls to map_page().

These advanced callers already manage their data in some sort of
database and can perform IOVA allocation in advance, leaving range
linkage operation to be in fast path.

Provide an interface to allocate/deallocate IOVA and next patch
link/unlink DMA ranges to that specific IOVA.

The API is exported from dma-iommu as it is the only implementation
supported, the namespace is clearly different from iommu_* functions
which are not allowed to be used. This code layout allows us to save
function call per API call used in datapath as well as a lot of boilerplate
code.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/iommu/dma-iommu.c   | 79 +++++++++++++++++++++++++++++++++++++
 include/linux/dma-mapping.h | 15 +++++++
 2 files changed, 94 insertions(+)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index c422e36c0d66..0644152c5aad 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1745,6 +1745,85 @@ size_t iommu_dma_max_mapping_size(struct device *dev)
 	return SIZE_MAX;
 }
 
+static bool iommu_dma_iova_alloc(struct device *dev,
+		struct dma_iova_state *state, phys_addr_t phys, size_t size)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	size_t iova_off = iova_offset(iovad, phys);
+	dma_addr_t addr;
+
+	if (WARN_ON_ONCE(!size))
+		return false;
+	if (WARN_ON_ONCE(size & DMA_IOVA_USE_SWIOTLB))
+		return false;
+
+	addr = iommu_dma_alloc_iova(domain,
+			iova_align(iovad, size + iova_off),
+			dma_get_mask(dev), dev);
+	if (!addr)
+		return false;
+
+	state->addr = addr + iova_off;
+	state->__size = size;
+	return true;
+}
+
+/**
+ * dma_iova_try_alloc - Try to allocate an IOVA space
+ * @dev: Device to allocate the IOVA space for
+ * @state: IOVA state
+ * @phys: physical address
+ * @size: IOVA size
+ *
+ * Check if @dev supports the IOVA-based DMA API, and if yes allocate IOVA space
+ * for the given base address and size.
+ *
+ * Note: @phys is only used to calculate the IOVA alignment. Callers that always
+ * do PAGE_SIZE aligned transfers can safely pass 0 here.
+ *
+ * Returns %true if the IOVA-based DMA API can be used and IOVA space has been
+ * allocated, or %false if the regular DMA API should be used.
+ */
+bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state,
+		phys_addr_t phys, size_t size)
+{
+	memset(state, 0, sizeof(*state));
+	if (!use_dma_iommu(dev))
+		return false;
+	if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&
+	    iommu_deferred_attach(dev, iommu_get_domain_for_dev(dev)))
+		return false;
+	return iommu_dma_iova_alloc(dev, state, phys, size);
+}
+EXPORT_SYMBOL_GPL(dma_iova_try_alloc);
+
+/**
+ * dma_iova_free - Free an IOVA space
+ * @dev: Device to free the IOVA space for
+ * @state: IOVA state
+ *
+ * Undoes a successful dma_try_iova_alloc().
+ *
+ * Note that all dma_iova_link() calls need to be undone first.  For callers
+ * that never call dma_iova_unlink(), dma_iova_destroy() can be used instead
+ * which unlinks all ranges and frees the IOVA space in a single efficient
+ * operation.
+ */
+void dma_iova_free(struct device *dev, struct dma_iova_state *state)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	size_t iova_start_pad = iova_offset(iovad, state->addr);
+	size_t size = dma_iova_size(state);
+
+	iommu_dma_free_iova(cookie, state->addr - iova_start_pad,
+			iova_align(iovad, size + iova_start_pad), NULL);
+}
+EXPORT_SYMBOL_GPL(dma_iova_free);
+
 void iommu_setup_dma_ops(struct device *dev)
 {
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 6075e0708deb..817f11bce7bc 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -11,6 +11,7 @@
 #include <linux/scatterlist.h>
 #include <linux/bug.h>
 #include <linux/mem_encrypt.h>
+#include <linux/iommu.h>
 
 /**
  * List of possible attributes associated with a DMA mapping. The semantics
@@ -77,6 +78,7 @@
 #define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
 
 struct dma_iova_state {
+	dma_addr_t addr;
 	size_t __size;
 };
 
@@ -307,11 +309,24 @@ static inline bool dma_use_iova(struct dma_iova_state *state)
 {
 	return state->__size != 0;
 }
+
+bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state,
+		phys_addr_t phys, size_t size);
+void dma_iova_free(struct device *dev, struct dma_iova_state *state);
 #else /* CONFIG_IOMMU_DMA */
 static inline bool dma_use_iova(struct dma_iova_state *state)
 {
 	return false;
 }
+static inline bool dma_iova_try_alloc(struct device *dev,
+		struct dma_iova_state *state, phys_addr_t phys, size_t size)
+{
+	return false;
+}
+static inline void dma_iova_free(struct device *dev,
+		struct dma_iova_state *state)
+{
+}
 #endif /* CONFIG_IOMMU_DMA */
 
 #if defined(CONFIG_HAS_DMA) && defined(CONFIG_DMA_NEED_SYNC)
-- 
2.46.2

[PATCH 06/18] iommu/dma: Factor out a iommu_dma_map_swiotlb helper

[Leon Romanovsky]

From: Christoph Hellwig <hch@lst.de>

Split the iommu logic from iommu_dma_map_page into a separate helper.
This not only keeps the code neatly separated, but will also allow for
reuse in another caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/iommu/dma-iommu.c | 73 ++++++++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 32 deletions(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index 0644152c5aad..b859f93b1c17 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1161,6 +1161,43 @@ void iommu_dma_sync_sg_for_device(struct device *dev, struct scatterlist *sgl,
 			arch_sync_dma_for_device(sg_phys(sg), sg->length, dir);
 }
 
+static phys_addr_t iommu_dma_map_swiotlb(struct device *dev, phys_addr_t phys,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iova_domain *iovad = &domain->iova_cookie->iovad;
+
+	if (!is_swiotlb_active(dev)) {
+		dev_warn_once(dev, "DMA bounce buffers are inactive, unable to map unaligned transaction.\n");
+		return DMA_MAPPING_ERROR;
+	}
+
+	trace_swiotlb_bounced(dev, phys, size);
+
+	phys = swiotlb_tbl_map_single(dev, phys, size, iova_mask(iovad), dir,
+			attrs);
+
+	/*
+	 * Untrusted devices should not see padding areas with random leftover
+	 * kernel data, so zero the pre- and post-padding.
+	 * swiotlb_tbl_map_single() has initialized the bounce buffer proper to
+	 * the contents of the original memory buffer.
+	 */
+	if (phys != DMA_MAPPING_ERROR && dev_is_untrusted(dev)) {
+		size_t start, virt = (size_t)phys_to_virt(phys);
+
+		/* Pre-padding */
+		start = iova_align_down(iovad, virt);
+		memset((void *)start, 0, virt - start);
+
+		/* Post-padding */
+		start = virt + size;
+		memset((void *)start, 0, iova_align(iovad, start) - start);
+	}
+
+	return phys;
+}
+
 dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
 	      unsigned long offset, size_t size, enum dma_data_direction dir,
 	      unsigned long attrs)
@@ -1174,42 +1211,14 @@ dma_addr_t iommu_dma_map_page(struct device *dev, struct page *page,
 	dma_addr_t iova, dma_mask = dma_get_mask(dev);
 
 	/*
-	 * If both the physical buffer start address and size are
-	 * page aligned, we don't need to use a bounce page.
+	 * If both the physical buffer start address and size are page aligned,
+	 * we don't need to use a bounce page.
 	 */
 	if (dev_use_swiotlb(dev, size, dir) &&
 	    iova_offset(iovad, phys | size)) {
-		if (!is_swiotlb_active(dev)) {
-			dev_warn_once(dev, "DMA bounce buffers are inactive, unable to map unaligned transaction.\n");
-			return DMA_MAPPING_ERROR;
-		}
-
-		trace_swiotlb_bounced(dev, phys, size);
-
-		phys = swiotlb_tbl_map_single(dev, phys, size,
-					      iova_mask(iovad), dir, attrs);
-
+		phys = iommu_dma_map_swiotlb(dev, phys, size, dir, attrs);
 		if (phys == DMA_MAPPING_ERROR)
-			return DMA_MAPPING_ERROR;
-
-		/*
-		 * Untrusted devices should not see padding areas with random
-		 * leftover kernel data, so zero the pre- and post-padding.
-		 * swiotlb_tbl_map_single() has initialized the bounce buffer
-		 * proper to the contents of the original memory buffer.
-		 */
-		if (dev_is_untrusted(dev)) {
-			size_t start, virt = (size_t)phys_to_virt(phys);
-
-			/* Pre-padding */
-			start = iova_align_down(iovad, virt);
-			memset((void *)start, 0, virt - start);
-
-			/* Post-padding */
-			start = virt + size;
-			memset((void *)start, 0,
-			       iova_align(iovad, start) - start);
-		}
+			return phys;
 	}
 
 	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
-- 
2.46.2

[PATCH 07/18] dma-mapping: Implement link/unlink ranges API

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

Introduce new DMA APIs to perform DMA linkage of buffers
in layers higher than DMA.

In proposed API, the callers will perform the following steps.
In map path:
	if (dma_can_use_iova(...))
	    dma_iova_alloc()
	    for (page in range)
	       dma_iova_link_next(...)
	    dma_iova_sync(...)
	else
	     /* Fallback to legacy map pages */
             for (all pages)
	       dma_map_page(...)

In unmap path:
	if (dma_can_use_iova(...))
	     dma_iova_destroy()
	else
	     for (all pages)
		dma_unmap_page(...)

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/iommu/dma-iommu.c   | 256 ++++++++++++++++++++++++++++++++++++
 include/linux/dma-map-ops.h |   1 -
 include/linux/dma-mapping.h |  31 +++++
 3 files changed, 287 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
index b859f93b1c17..f853762c2d54 100644
--- a/drivers/iommu/dma-iommu.c
+++ b/drivers/iommu/dma-iommu.c
@@ -1833,6 +1833,262 @@ void dma_iova_free(struct device *dev, struct dma_iova_state *state)
 }
 EXPORT_SYMBOL_GPL(dma_iova_free);
 
+static int __dma_iova_link(struct device *dev, dma_addr_t addr,
+		phys_addr_t phys, size_t size, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+	bool coherent = dev_is_dma_coherent(dev);
+
+	if (!coherent && !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+		arch_sync_dma_for_device(phys, size, dir);
+
+	return iommu_map_nosync(iommu_get_dma_domain(dev), addr, phys, size,
+			dma_info_to_prot(dir, coherent, attrs), GFP_ATOMIC);
+}
+
+static int iommu_dma_iova_bounce_and_link(struct device *dev, dma_addr_t addr,
+		phys_addr_t phys, size_t bounce_len,
+		enum dma_data_direction dir, unsigned long attrs,
+		size_t iova_start_pad)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iova_domain *iovad = &domain->iova_cookie->iovad;
+	phys_addr_t bounce_phys;
+	int error;
+
+	bounce_phys = iommu_dma_map_swiotlb(dev, phys, bounce_len, dir, attrs);
+	if (bounce_phys == DMA_MAPPING_ERROR)
+		return -ENOMEM;
+
+	error = __dma_iova_link(dev, addr - iova_start_pad,
+			bounce_phys - iova_start_pad,
+			iova_align(iovad, bounce_len), dir, attrs);
+	if (error)
+		swiotlb_tbl_unmap_single(dev, bounce_phys, bounce_len, dir,
+				attrs);
+	return error;
+}
+
+static int iommu_dma_iova_link_swiotlb(struct device *dev,
+		struct dma_iova_state *state, phys_addr_t phys, size_t offset,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	size_t iova_start_pad = iova_offset(iovad, phys);
+	size_t iova_end_pad = iova_offset(iovad, phys + size);
+	dma_addr_t addr = state->addr + offset;
+	size_t mapped = 0;
+	int error;
+
+	if (iova_start_pad) {
+		size_t bounce_len = min(size, iovad->granule - iova_start_pad);
+
+		error = iommu_dma_iova_bounce_and_link(dev, addr, phys,
+				bounce_len, dir, attrs, iova_start_pad);
+		if (error)
+			return error;
+		state->__size |= DMA_IOVA_USE_SWIOTLB;
+
+		mapped += bounce_len;
+		size -= bounce_len;
+		if (!size)
+			return 0;
+	}
+
+	size -= iova_end_pad;
+	error = __dma_iova_link(dev, addr + mapped, phys + mapped, size, dir,
+			attrs);
+	if (error)
+		goto out_unmap;
+	mapped += size;
+
+	if (iova_end_pad) {
+		error = iommu_dma_iova_bounce_and_link(dev, addr + mapped,
+				phys + mapped, iova_end_pad, dir, attrs, 0);
+		if (error)
+			goto out_unmap;
+		state->__size |= DMA_IOVA_USE_SWIOTLB;
+	}
+
+	return 0;
+
+out_unmap:
+	dma_iova_unlink(dev, state, 0, mapped, dir, attrs);
+	return error;
+}
+
+/**
+ * dma_iova_link - Link a range of IOVA space
+ * @dev: DMA device
+ * @state: IOVA state
+ * @phys: physical address to link
+ * @offset: offset into the IOVA state to map into
+ * @size: size of the buffer
+ * @dir: DMA direction
+ * @attrs: attributes of mapping properties
+ *
+ * Link a range of IOVA space for the given IOVA state without IOTLB sync.
+ * This function is used to link multiple physical addresses in contigueous
+ * IOVA space without performing costly IOTLB sync.
+ *
+ * The caller is responsible to call to dma_iova_sync() to sync IOTLB at
+ * the end of linkage.
+ */
+int dma_iova_link(struct device *dev, struct dma_iova_state *state,
+		phys_addr_t phys, size_t offset, size_t size,
+		enum dma_data_direction dir, unsigned long attrs)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	size_t iova_start_pad = iova_offset(iovad, phys);
+
+	if (WARN_ON_ONCE(iova_start_pad && offset > 0))
+		return -EIO;
+
+	if (dev_use_swiotlb(dev, size, dir) && iova_offset(iovad, phys | size))
+		return iommu_dma_iova_link_swiotlb(dev, state, phys, offset,
+				size, dir, attrs);
+
+	return __dma_iova_link(dev, state->addr + offset - iova_start_pad,
+			phys - iova_start_pad,
+			iova_align(iovad, size + iova_start_pad), dir, attrs);
+}
+EXPORT_SYMBOL_GPL(dma_iova_link);
+
+/**
+ * dma_iova_sync - Sync IOTLB
+ * @dev: DMA device
+ * @state: IOVA state
+ * @offset: offset into the IOVA state to sync
+ * @size: size of the buffer
+ * @ret: return value from the last IOVA operation
+ *
+ * Sync IOTLB for the given IOVA state. This function should be called on
+ * the IOVA-contigous range created by one ore more dma_iova_link() calls
+ * to sync the IOTLB.
+ */
+int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
+		size_t offset, size_t size, int ret)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	dma_addr_t addr = state->addr + offset;
+	size_t iova_start_pad = iova_offset(iovad, addr);
+
+	addr -= iova_start_pad;
+	size = iova_align(iovad, size + iova_start_pad);
+
+	if (!ret)
+		ret = iommu_sync_map(domain, addr, size);
+	if (ret)
+		iommu_unmap(domain, addr, size);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dma_iova_sync);
+
+static void iommu_dma_iova_unlink_range_slow(struct device *dev,
+		dma_addr_t addr, size_t size, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	size_t iova_start_pad = iova_offset(iovad, addr);
+	dma_addr_t end = addr + size;
+
+	do {
+		phys_addr_t phys;
+		size_t len;
+
+		phys = iommu_iova_to_phys(domain, addr);
+		if (WARN_ON(!phys))
+			continue;
+		len = min_t(size_t,
+			end - addr, iovad->granule - iova_start_pad);
+
+		if (!dev_is_dma_coherent(dev) &&
+		    !(attrs & DMA_ATTR_SKIP_CPU_SYNC))
+			arch_sync_dma_for_cpu(phys, len, dir);
+
+		swiotlb_tbl_unmap_single(dev, phys, len, dir, attrs);
+
+		addr += len;
+		iova_start_pad = 0;
+	} while (addr < end);
+}
+
+static void __iommu_dma_iova_unlink(struct device *dev,
+		struct dma_iova_state *state, size_t offset, size_t size,
+		enum dma_data_direction dir, unsigned long attrs,
+		bool free_iova)
+{
+	struct iommu_domain *domain = iommu_get_dma_domain(dev);
+	struct iommu_dma_cookie *cookie = domain->iova_cookie;
+	struct iova_domain *iovad = &cookie->iovad;
+	dma_addr_t addr = state->addr + offset;
+	size_t iova_start_pad = iova_offset(iovad, addr);
+	struct iommu_iotlb_gather iotlb_gather;
+	size_t unmapped;
+
+	if ((state->__size & DMA_IOVA_USE_SWIOTLB) ||
+	    (!dev_is_dma_coherent(dev) && !(attrs & DMA_ATTR_SKIP_CPU_SYNC)))
+		iommu_dma_iova_unlink_range_slow(dev, addr, size, dir, attrs);
+
+	iommu_iotlb_gather_init(&iotlb_gather);
+	iotlb_gather.queued = free_iova && READ_ONCE(cookie->fq_domain);
+
+	size = iova_align(iovad, size + iova_start_pad);
+	addr -= iova_start_pad;
+	unmapped = iommu_unmap_fast(domain, addr, size, &iotlb_gather);
+	WARN_ON(unmapped != size);
+
+	if (!iotlb_gather.queued)
+		iommu_iotlb_sync(domain, &iotlb_gather);
+	if (free_iova)
+		iommu_dma_free_iova(cookie, addr, size, &iotlb_gather);
+}
+
+/**
+ * dma_iova_unlink - Unlink a range of IOVA space
+ * @dev: DMA device
+ * @state: IOVA state
+ * @offset: offset into the IOVA state to unlink
+ * @size: size of the buffer
+ * @dir: DMA direction
+ * @attrs: attributes of mapping properties
+ *
+ * Unlink a range of IOVA space for the given IOVA state.
+ */
+void dma_iova_unlink(struct device *dev, struct dma_iova_state *state,
+		size_t offset, size_t size, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+	 __iommu_dma_iova_unlink(dev, state, offset, size, dir, attrs, false);
+}
+EXPORT_SYMBOL_GPL(dma_iova_unlink);
+
+/**
+ * dma_iova_destroy - Finish a DMA mapping transaction
+ * @dev: DMA device
+ * @state: IOVA state
+ * @dir: DMA direction
+ * @attrs: attributes of mapping properties
+ *
+ * Unlink whole IOVA range and free an IOVA space. The range of IOVA from
+ * dma_addr to size must all be linked, and be the only linked IOVA in state
+ */
+void dma_iova_destroy(struct device *dev, struct dma_iova_state *state,
+		enum dma_data_direction dir, unsigned long attrs)
+{
+	__iommu_dma_iova_unlink(dev, state, 0, dma_iova_size(state), dir, attrs,
+			true);
+}
+EXPORT_SYMBOL_GPL(dma_iova_destroy);
+
 void iommu_setup_dma_ops(struct device *dev)
 {
 	struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
index 6ee626e50708..dced37816ede 100644
--- a/include/linux/dma-map-ops.h
+++ b/include/linux/dma-map-ops.h
@@ -434,5 +434,4 @@ static inline void debug_dma_dump_mappings(struct device *dev)
 #endif /* CONFIG_DMA_API_DEBUG */
 
 extern const struct dma_map_ops dma_dummy_ops;
-
 #endif /* _LINUX_DMA_MAP_OPS_H */
diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 817f11bce7bc..50f0edfe7350 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -313,6 +313,16 @@ static inline bool dma_use_iova(struct dma_iova_state *state)
 bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state,
 		phys_addr_t phys, size_t size);
 void dma_iova_free(struct device *dev, struct dma_iova_state *state);
+void dma_iova_destroy(struct device *dev, struct dma_iova_state *state,
+		enum dma_data_direction dir, unsigned long attrs);
+int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
+		size_t offset, size_t size, int ret);
+int dma_iova_link(struct device *dev, struct dma_iova_state *state,
+		phys_addr_t phys, size_t offset, size_t size,
+		enum dma_data_direction dir, unsigned long attrs);
+void dma_iova_unlink(struct device *dev, struct dma_iova_state *state,
+		size_t offset, size_t size, enum dma_data_direction dir,
+		unsigned long attrs);
 #else /* CONFIG_IOMMU_DMA */
 static inline bool dma_use_iova(struct dma_iova_state *state)
 {
@@ -327,6 +337,27 @@ static inline void dma_iova_free(struct device *dev,
 		struct dma_iova_state *state)
 {
 }
+static inline void dma_iova_destroy(struct device *dev,
+		struct dma_iova_state *state, enum dma_data_direction dir,
+		unsigned long attrs)
+{
+}
+static inline int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
+		size_t offset, size_t size, int ret)
+{
+	return -EOPNOTSUPP;
+}
+static inline int dma_iova_link(struct device *dev,
+		struct dma_iova_state *state, phys_addr_t phys, size_t offset,
+		size_t size, enum dma_data_direction dir, unsigned long attrs)
+{
+	return -EOPNOTSUPP;
+}
+static inline void dma_iova_unlink(struct device *dev,
+		struct dma_iova_state *state, size_t offset, size_t size,
+		enum dma_data_direction dir, unsigned long attrs)
+{
+}
 #endif /* CONFIG_IOMMU_DMA */
 
 #if defined(CONFIG_HAS_DMA) && defined(CONFIG_DMA_NEED_SYNC)
-- 
2.46.2

[PATCH 08/18] dma-mapping: add a dma_need_unmap helper

[Leon Romanovsky]

From: Christoph Hellwig <hch@lst.de>

Add helper that allows a driver to skip calling dma_unmap_*
if the DMA layer can guarantee that they are no-nops.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 include/linux/dma-mapping.h |  5 +++++
 kernel/dma/mapping.c        | 20 ++++++++++++++++++++
 2 files changed, 25 insertions(+)

diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
index 50f0edfe7350..c3edd6c3e1ab 100644
--- a/include/linux/dma-mapping.h
+++ b/include/linux/dma-mapping.h
@@ -409,6 +409,7 @@ static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
 {
 	return dma_dev_need_sync(dev) ? __dma_need_sync(dev, dma_addr) : false;
 }
+bool dma_need_unmap(struct device *dev);
 #else /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */
 static inline bool dma_dev_need_sync(const struct device *dev)
 {
@@ -434,6 +435,10 @@ static inline bool dma_need_sync(struct device *dev, dma_addr_t dma_addr)
 {
 	return false;
 }
+static inline bool dma_need_unmap(struct device *dev)
+{
+	return false;
+}
 #endif /* !CONFIG_HAS_DMA || !CONFIG_DMA_NEED_SYNC */
 
 struct page *dma_alloc_pages(struct device *dev, size_t size,
diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c
index 864a1121bf08..daa97a650778 100644
--- a/kernel/dma/mapping.c
+++ b/kernel/dma/mapping.c
@@ -442,6 +442,26 @@ bool __dma_need_sync(struct device *dev, dma_addr_t dma_addr)
 }
 EXPORT_SYMBOL_GPL(__dma_need_sync);
 
+/**
+ * dma_need_unmap - does this device need dma_unmap_* operations
+ * @dev: device to check
+ *
+ * If this function returns %false, drivers can skip calling dma_unmap_* after
+ * finishing an I/O.  This function must be called after all mappings that might
+ * need to be unmapped have been performed.
+ */
+bool dma_need_unmap(struct device *dev)
+{
+	if (!dma_map_direct(dev, get_dma_ops(dev)))
+		return true;
+#ifdef CONFIG_DMA_NEED_SYNC
+	if (!dev->dma_skip_sync)
+		return true;
+#endif
+	return IS_ENABLED(CONFIG_DMA_API_DEBUG);
+}
+EXPORT_SYMBOL_GPL(dma_need_unmap);
+
 static void dma_setup_need_sync(struct device *dev)
 {
 	const struct dma_map_ops *ops = get_dma_ops(dev);
-- 
2.46.2

[PATCH 09/18] docs: core-api: document the IOVA-based API

[Leon Romanovsky]

From: Christoph Hellwig <hch@lst.de>

Add an explanation of the newly added IOVA-based mapping API.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 Documentation/core-api/dma-api.rst | 70 ++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/Documentation/core-api/dma-api.rst b/Documentation/core-api/dma-api.rst
index 8e3cce3d0a23..9ecbff473d9a 100644
--- a/Documentation/core-api/dma-api.rst
+++ b/Documentation/core-api/dma-api.rst
@@ -530,6 +530,76 @@ routines, e.g.:::
 		....
 	}
 
+Part Ie - IOVA-based DMA mappings
+---------------------------------
+
+These APIs allow a very efficient mapping when using an IOMMU.  They are an
+optional path that requires extra code and are only recommended for drivers
+where DMA mapping performance, or the space usage for storing the dma addresses
+matter.  All the consideration from the previous section apply here as well.
+
+::
+
+    bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state,
+		phys_addr_t phys, size_t size);
+
+Is used to try to allocate IOVA space for mapping operation.  If it returns
+false this API can't be used for the given device and the normal streaming
+DMA mapping API should be used.  The ``struct dma_iova_state`` is allocated
+by the driver and must be kept around until unmap time.
+
+::
+
+    static inline bool dma_use_iova(struct dma_iova_state *state)
+
+Can be used by the driver to check if the IOVA-based API is used after a
+call to dma_iova_try_alloc.  This can be useful in the unmap path.
+
+::
+
+    int dma_iova_link(struct device *dev, struct dma_iova_state *state,
+		phys_addr_t phys, size_t offset, size_t size,
+		enum dma_data_direction dir, unsigned long attrs);
+
+Is used to link ranges to the IOVA previously allocated.  The start of all
+but the first call to dma_iova_link for a given state must be aligned
+to the DMA merge boundary returned by ``dma_get_merge_boundary())``, and
+the size of all but the last range must be aligned to the DMA merge boundary
+as well.
+
+::
+
+    int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
+		size_t offset, size_t size, int ret);
+
+Must called to sync the IOMMU page tables for IOVA-range mapped by one or
+more calls to ``dma_iova_link()``.
+
+For drivers that use a one-shot mapping, all ranges can be unmapped and the
+IOVA freed by calling:
+
+::
+
+   void dma_iova_destroy(struct device *dev, struct dma_iova_state *state,
+		enum dma_data_direction dir, unsigned long attrs);
+
+Alternatively drivers can dynamically manage the IOVA space by unmapping
+and mapping individual regions.  In that case
+
+::
+
+    void dma_iova_unlink(struct device *dev, struct dma_iova_state *state,
+		size_t offset, size_t size, enum dma_data_direction dir,
+		unsigned long attrs);
+
+is used to unmap a range previous mapped, and
+
+::
+
+   void dma_iova_free(struct device *dev, struct dma_iova_state *state);
+
+is used to free the IOVA space.  All regions must have been unmapped using
+``dma_iova_unlink()`` before calling ``dma_iova_free()``.
 
 Part II - Non-coherent DMA allocations
 --------------------------------------
-- 
2.46.2

[PATCH 10/18] mm/hmm: let users to tag specific PFN with DMA mapped bit

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

Introduce new sticky flag (HMM_PFN_DMA_MAPPED), which isn't overwritten
by HMM range fault. Such flag allows users to tag specific PFNs with information
if this specific PFN was already DMA mapped.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 include/linux/hmm.h | 14 ++++++++++++++
 mm/hmm.c            | 34 +++++++++++++++++++++-------------
 2 files changed, 35 insertions(+), 13 deletions(-)

diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 126a36571667..5dd655f6766b 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -23,6 +23,8 @@ struct mmu_interval_notifier;
  * HMM_PFN_WRITE - if the page memory can be written to (requires HMM_PFN_VALID)
  * HMM_PFN_ERROR - accessing the pfn is impossible and the device should
  *                 fail. ie poisoned memory, special pages, no vma, etc
+ * HMM_PFN_DMA_MAPPED - Flag preserved on input-to-output transformation
+ *                      to mark that page is already DMA mapped
  *
  * On input:
  * 0                 - Return the current state of the page, do not fault it.
@@ -36,6 +38,10 @@ enum hmm_pfn_flags {
 	HMM_PFN_VALID = 1UL << (BITS_PER_LONG - 1),
 	HMM_PFN_WRITE = 1UL << (BITS_PER_LONG - 2),
 	HMM_PFN_ERROR = 1UL << (BITS_PER_LONG - 3),
+
+	/* Sticky flag, carried from Input to Output */
+	HMM_PFN_DMA_MAPPED = 1UL << (BITS_PER_LONG - 7),
+
 	HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 8),
 
 	/* Input flags */
@@ -57,6 +63,14 @@ static inline struct page *hmm_pfn_to_page(unsigned long hmm_pfn)
 	return pfn_to_page(hmm_pfn & ~HMM_PFN_FLAGS);
 }
 
+/*
+ * hmm_pfn_to_phys() - return physical address pointed to by a device entry
+ */
+static inline phys_addr_t hmm_pfn_to_phys(unsigned long hmm_pfn)
+{
+	return __pfn_to_phys(hmm_pfn & ~HMM_PFN_FLAGS);
+}
+
 /*
  * hmm_pfn_to_map_order() - return the CPU mapping size order
  *
diff --git a/mm/hmm.c b/mm/hmm.c
index 7e0229ae4a5a..2a0c34d7cb2b 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -44,8 +44,10 @@ static int hmm_pfns_fill(unsigned long addr, unsigned long end,
 {
 	unsigned long i = (addr - range->start) >> PAGE_SHIFT;
 
-	for (; addr < end; addr += PAGE_SIZE, i++)
-		range->hmm_pfns[i] = cpu_flags;
+	for (; addr < end; addr += PAGE_SIZE, i++) {
+		range->hmm_pfns[i] &= HMM_PFN_DMA_MAPPED;
+		range->hmm_pfns[i] |= cpu_flags;
+	}
 	return 0;
 }
 
@@ -202,8 +204,10 @@ static int hmm_vma_handle_pmd(struct mm_walk *walk, unsigned long addr,
 		return hmm_vma_fault(addr, end, required_fault, walk);
 
 	pfn = pmd_pfn(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
-	for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++)
-		hmm_pfns[i] = pfn | cpu_flags;
+	for (i = 0; addr < end; addr += PAGE_SIZE, i++, pfn++) {
+		hmm_pfns[i] &= HMM_PFN_DMA_MAPPED;
+		hmm_pfns[i] |= pfn | cpu_flags;
+	}
 	return 0;
 }
 #else /* CONFIG_TRANSPARENT_HUGEPAGE */
@@ -236,7 +240,7 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
 			hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
 		if (required_fault)
 			goto fault;
-		*hmm_pfn = 0;
+		*hmm_pfn = *hmm_pfn & HMM_PFN_DMA_MAPPED;
 		return 0;
 	}
 
@@ -253,14 +257,14 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
 			cpu_flags = HMM_PFN_VALID;
 			if (is_writable_device_private_entry(entry))
 				cpu_flags |= HMM_PFN_WRITE;
-			*hmm_pfn = swp_offset_pfn(entry) | cpu_flags;
+			*hmm_pfn = (*hmm_pfn & HMM_PFN_DMA_MAPPED) | swp_offset_pfn(entry) | cpu_flags;
 			return 0;
 		}
 
 		required_fault =
 			hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0);
 		if (!required_fault) {
-			*hmm_pfn = 0;
+			*hmm_pfn = *hmm_pfn & HMM_PFN_DMA_MAPPED;
 			return 0;
 		}
 
@@ -304,11 +308,11 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr,
 			pte_unmap(ptep);
 			return -EFAULT;
 		}
-		*hmm_pfn = HMM_PFN_ERROR;
+		*hmm_pfn = (*hmm_pfn & HMM_PFN_DMA_MAPPED) | HMM_PFN_ERROR;
 		return 0;
 	}
 
-	*hmm_pfn = pte_pfn(pte) | cpu_flags;
+	*hmm_pfn = (*hmm_pfn & HMM_PFN_DMA_MAPPED) | pte_pfn(pte) | cpu_flags;
 	return 0;
 
 fault:
@@ -448,8 +452,10 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long start, unsigned long end,
 		}
 
 		pfn = pud_pfn(pud) + ((addr & ~PUD_MASK) >> PAGE_SHIFT);
-		for (i = 0; i < npages; ++i, ++pfn)
-			hmm_pfns[i] = pfn | cpu_flags;
+		for (i = 0; i < npages; ++i, ++pfn) {
+			hmm_pfns[i] &= HMM_PFN_DMA_MAPPED;
+			hmm_pfns[i] |= pfn | cpu_flags;
+		}
 		goto out_unlock;
 	}
 
@@ -507,8 +513,10 @@ static int hmm_vma_walk_hugetlb_entry(pte_t *pte, unsigned long hmask,
 	}
 
 	pfn = pte_pfn(entry) + ((start & ~hmask) >> PAGE_SHIFT);
-	for (; addr < end; addr += PAGE_SIZE, i++, pfn++)
-		range->hmm_pfns[i] = pfn | cpu_flags;
+	for (; addr < end; addr += PAGE_SIZE, i++, pfn++) {
+		range->hmm_pfns[i] &= HMM_PFN_DMA_MAPPED;
+		range->hmm_pfns[i] |= pfn | cpu_flags;
+	}
 
 	spin_unlock(ptl);
 	return 0;
-- 
2.46.2

[PATCH 11/18] mm/hmm: provide generic DMA managing logic

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

HMM callers use PFN list to populate range while calling
to hmm_range_fault(), the conversion from PFN to DMA address
is done by the callers with help of another DMA list. However,
it is wasteful on any modern platform and by doing the right
logic, that DMA list can be avoided.

Provide generic logic to manage these lists and gave an interface
to map/unmap PFNs to DMA addresses, without requiring from the callers
to be an experts in DMA core API.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 include/linux/hmm-dma.h |  32 +++++++
 include/linux/hmm.h     |   2 +
 mm/hmm.c                | 195 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 229 insertions(+)
 create mode 100644 include/linux/hmm-dma.h

diff --git a/include/linux/hmm-dma.h b/include/linux/hmm-dma.h
new file mode 100644
index 000000000000..f6ce2a00d74d
--- /dev/null
+++ b/include/linux/hmm-dma.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (c) 2024 NVIDIA Corporation & Affiliates */
+#ifndef LINUX_HMM_DMA_H
+#define LINUX_HMM_DMA_H
+
+#include <linux/dma-mapping.h>
+
+struct dma_iova_state;
+struct pci_p2pdma_map_state;
+
+/*
+ * struct hmm_dma_map - array of PFNs and DMA addresses
+ *
+ * @state: DMA IOVA state
+ * @pfns: array of PFNs
+ * @dma_list: array of DMA addresses
+ * @dma_entry_size: size of each DMA entry in the array
+ */
+struct hmm_dma_map {
+	struct dma_iova_state state;
+	unsigned long *pfn_list;
+	dma_addr_t *dma_list;
+	size_t dma_entry_size;
+};
+
+int hmm_dma_map_alloc(struct device *dev, struct hmm_dma_map *map,
+		      size_t nr_entries, size_t dma_entry_size);
+void hmm_dma_map_free(struct device *dev, struct hmm_dma_map *map);
+dma_addr_t hmm_dma_map_pfn(struct device *dev, struct hmm_dma_map *map,
+			   size_t idx, struct pci_p2pdma_map_state *p2pdma_state);
+bool hmm_dma_unmap_pfn(struct device *dev, struct hmm_dma_map *map, size_t idx);
+#endif /* LINUX_HMM_DMA_H */
diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index 5dd655f6766b..62980ca8f3c5 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -23,6 +23,7 @@ struct mmu_interval_notifier;
  * HMM_PFN_WRITE - if the page memory can be written to (requires HMM_PFN_VALID)
  * HMM_PFN_ERROR - accessing the pfn is impossible and the device should
  *                 fail. ie poisoned memory, special pages, no vma, etc
+ * HMM_PFN_P2PDMA_BUS - Bus mapped P2P transfer
  * HMM_PFN_DMA_MAPPED - Flag preserved on input-to-output transformation
  *                      to mark that page is already DMA mapped
  *
@@ -40,6 +41,7 @@ enum hmm_pfn_flags {
 	HMM_PFN_ERROR = 1UL << (BITS_PER_LONG - 3),
 
 	/* Sticky flag, carried from Input to Output */
+	HMM_PFN_P2PDMA_BUS = 1UL << (BITS_PER_LONG - 6),
 	HMM_PFN_DMA_MAPPED = 1UL << (BITS_PER_LONG - 7),
 
 	HMM_PFN_ORDER_SHIFT = (BITS_PER_LONG - 8),
diff --git a/mm/hmm.c b/mm/hmm.c
index 2a0c34d7cb2b..85cd6f20303c 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -10,6 +10,7 @@
  */
 #include <linux/pagewalk.h>
 #include <linux/hmm.h>
+#include <linux/hmm-dma.h>
 #include <linux/init.h>
 #include <linux/rmap.h>
 #include <linux/swap.h>
@@ -23,6 +24,7 @@
 #include <linux/sched/mm.h>
 #include <linux/jump_label.h>
 #include <linux/dma-mapping.h>
+#include <linux/pci-p2pdma.h>
 #include <linux/mmu_notifier.h>
 #include <linux/memory_hotplug.h>
 
@@ -615,3 +617,196 @@ int hmm_range_fault(struct hmm_range *range)
 	return ret;
 }
 EXPORT_SYMBOL(hmm_range_fault);
+
+/**
+ * hmm_dma_map_alloc - Allocate HMM map structure
+ * @dev: device to allocate structure for
+ * @map: HMM map to allocate
+ * @nr_entries: number of entries in the map
+ * @dma_entry_size: size of the DMA entry in the map
+ *
+ * Allocate the HMM map structure and all the lists it contains.
+ * Return 0 on success, -ENOMEM on failure.
+ */
+int hmm_dma_map_alloc(struct device *dev, struct hmm_dma_map *map,
+		      size_t nr_entries, size_t dma_entry_size)
+{
+	bool dma_need_sync = false;
+	bool use_iova;
+
+	if (!(nr_entries * PAGE_SIZE / dma_entry_size))
+		return -EINVAL;
+
+	/*
+	 * The HMM API violates our normal DMA buffer ownership rules and can't
+	 * transfer buffer ownership.  The dma_addressing_limited() check is a
+	 * best approximation to ensure no swiotlb buffering happens.
+	 */
+	if (IS_ENABLED(CONFIG_DMA_NEED_SYNC))
+		dma_need_sync = !dev->dma_skip_sync;
+	if (dma_need_sync || dma_addressing_limited(dev))
+		return -EOPNOTSUPP;
+
+	map->dma_entry_size = dma_entry_size;
+	map->pfn_list =
+		kvcalloc(nr_entries, sizeof(*map->pfn_list), GFP_KERNEL);
+	if (!map->pfn_list)
+		return -ENOMEM;
+
+	use_iova = dma_iova_try_alloc(dev, &map->state, 0,
+			nr_entries * PAGE_SIZE);
+	if (!use_iova && dma_need_unmap(dev)) {
+		map->dma_list = kvcalloc(nr_entries, sizeof(*map->dma_list),
+					 GFP_KERNEL);
+		if (!map->dma_list)
+			goto err_dma;
+	}
+	return 0;
+
+err_dma:
+	kfree(map->pfn_list);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(hmm_dma_map_alloc);
+
+/**
+ * hmm_dma_map_free - iFree HMM map structure
+ * @dev: device to free structure from
+ * @map: HMM map containing the various lists and state
+ *
+ * Free the HMM map structure and all the lists it contains.
+ */
+void hmm_dma_map_free(struct device *dev, struct hmm_dma_map *map)
+{
+	if (dma_use_iova(&map->state))
+		dma_iova_free(dev, &map->state);
+	kfree(map->pfn_list);
+	kfree(map->dma_list);
+}
+EXPORT_SYMBOL_GPL(hmm_dma_map_free);
+
+/**
+ * hmm_dma_map_pfn - Map a physical HMM page to DMA address
+ * @dev: Device to map the page for
+ * @map: HMM map
+ * @idx: Index into the PFN and dma address arrays
+ * @pci_p2pdma_map_state: PCI P2P state.
+ *
+ * dma_alloc_iova() allocates IOVA based on the size specified by their use in
+ * iova->size. Call this function after IOVA allocation to link whole @page
+ * to get the DMA address. Note that very first call to this function
+ * will have @offset set to 0 in the IOVA space allocated from
+ * dma_alloc_iova(). For subsequent calls to this function on same @iova,
+ * @offset needs to be advanced by the caller with the size of previous
+ * page that was linked + DMA address returned for the previous page that was
+ * linked by this function.
+ */
+dma_addr_t hmm_dma_map_pfn(struct device *dev, struct hmm_dma_map *map,
+			   size_t idx, struct pci_p2pdma_map_state *p2pdma_state)
+{
+	struct dma_iova_state *state = &map->state;
+	dma_addr_t *dma_addrs = map->dma_list;
+	unsigned long *pfns = map->pfn_list;
+	struct page *page = hmm_pfn_to_page(pfns[idx]);
+	phys_addr_t paddr = hmm_pfn_to_phys(pfns[idx]);
+	size_t offset = idx * map->dma_entry_size;
+	dma_addr_t dma_addr;
+	int ret;
+
+	if ((pfns[idx] & HMM_PFN_DMA_MAPPED) &&
+	    !(pfns[idx] & HMM_PFN_P2PDMA_BUS)) {
+		/*
+		 * We are in this flow when there is a need to resync flags,
+		 * for example when page was already linked in prefetch call
+		 * with READ flag and now we need to add WRITE flag
+		 *
+		 * This page was already programmed to HW and we don't want/need
+		 * to unlink and link it again just to resync flags.
+		 */
+		if (dma_use_iova(state))
+			return state->addr + offset;
+
+		/*
+		 * Without dma_need_unmap, the dma_addrs array is NULL, thus we
+		 * need to regenerate the address below even if there already
+		 * was a mapping. But !dma_need_unmap implies that the
+		 * mapping stateless, so this is fine.
+		 */
+		if (dma_need_unmap(dev))
+			return dma_addrs[idx];
+
+		/* Continue to remapping */
+	}
+
+	switch (pci_p2pdma_state(p2pdma_state, dev, page)) {
+	case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
+	case PCI_P2PDMA_MAP_NONE:
+		break;
+	case PCI_P2PDMA_MAP_BUS_ADDR:
+		dma_addr = pci_p2pdma_bus_addr_map(p2pdma_state, paddr);
+		pfns[idx] |= HMM_PFN_P2PDMA_BUS;
+		goto done;
+	default:
+		return DMA_MAPPING_ERROR;
+	}
+
+	if (dma_use_iova(state)) {
+		ret = dma_iova_link(dev, state, paddr, offset,
+				    map->dma_entry_size, DMA_BIDIRECTIONAL, 0);
+		ret = dma_iova_sync(dev, state, offset, map->dma_entry_size,
+			ret);
+		if (ret)
+			return DMA_MAPPING_ERROR;
+
+		dma_addr = state->addr + offset;
+	} else {
+		if (WARN_ON_ONCE(dma_need_unmap(dev) && !dma_addrs))
+			return DMA_MAPPING_ERROR;
+
+		dma_addr = dma_map_page(dev, page, 0, map->dma_entry_size,
+					DMA_BIDIRECTIONAL);
+		if (dma_mapping_error(dev, dma_addr))
+			return DMA_MAPPING_ERROR;
+
+		if (dma_need_unmap(dev))
+			dma_addrs[idx] = dma_addr;
+	}
+
+done:
+	pfns[idx] |= HMM_PFN_DMA_MAPPED;
+	return dma_addr;
+}
+EXPORT_SYMBOL_GPL(hmm_dma_map_pfn);
+
+/**
+ * hmm_dma_unmap_pfn - Unmap a physical HMM page from DMA address
+ * @dev: Device to unmap the page from
+ * @map: HMM map
+ * @idx: Index of the PFN to unmap
+ *
+ * Returns true if the PFN was mapped and has been unmapped, false otherwise.
+ */
+bool hmm_dma_unmap_pfn(struct device *dev, struct hmm_dma_map *map, size_t idx)
+{
+	struct dma_iova_state *state = &map->state;
+	dma_addr_t *dma_addrs = map->dma_list;
+	unsigned long *pfns = map->pfn_list;
+
+#define HMM_PFN_VALID_DMA (HMM_PFN_VALID | HMM_PFN_DMA_MAPPED)
+	if ((pfns[idx] & HMM_PFN_VALID_DMA) != HMM_PFN_VALID_DMA)
+		return false;
+#undef HMM_PFN_VALID_DMA
+
+	if (pfns[idx] & HMM_PFN_P2PDMA_BUS)
+		; /* no need to unmap bus address P2P mappings */
+	else if (dma_use_iova(state))
+		dma_iova_unlink(dev, state, idx * map->dma_entry_size,
+				map->dma_entry_size, DMA_BIDIRECTIONAL, 0);
+	else if (dma_need_unmap(dev))
+		dma_unmap_page(dev, dma_addrs[idx], map->dma_entry_size,
+			       DMA_BIDIRECTIONAL);
+
+	pfns[idx] &= ~(HMM_PFN_DMA_MAPPED | HMM_PFN_P2PDMA_BUS);
+	return true;
+}
+EXPORT_SYMBOL_GPL(hmm_dma_unmap_pfn);
-- 
2.46.2

[PATCH 12/18] RDMA/umem: Store ODP access mask information in PFN

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

As a preparation to remove dma_list, store access mask in PFN pointer
and not in dma_addr_t.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/infiniband/core/umem_odp.c   | 100 +++++++++++----------------
 drivers/infiniband/hw/mlx5/mlx5_ib.h |   1 +
 drivers/infiniband/hw/mlx5/odp.c     |  37 +++++-----
 include/rdma/ib_umem_odp.h           |  14 +---
 4 files changed, 61 insertions(+), 91 deletions(-)

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index e9fa22d31c23..9dba369365af 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -296,22 +296,11 @@ EXPORT_SYMBOL(ib_umem_odp_release);
 static int ib_umem_odp_map_dma_single_page(
 		struct ib_umem_odp *umem_odp,
 		unsigned int dma_index,
-		struct page *page,
-		u64 access_mask)
+		struct page *page)
 {
 	struct ib_device *dev = umem_odp->umem.ibdev;
 	dma_addr_t *dma_addr = &umem_odp->dma_list[dma_index];
 
-	if (*dma_addr) {
-		/*
-		 * If the page is already dma mapped it means it went through
-		 * a non-invalidating trasition, like read-only to writable.
-		 * Resync the flags.
-		 */
-		*dma_addr = (*dma_addr & ODP_DMA_ADDR_MASK) | access_mask;
-		return 0;
-	}
-
 	*dma_addr = ib_dma_map_page(dev, page, 0, 1 << umem_odp->page_shift,
 				    DMA_BIDIRECTIONAL);
 	if (ib_dma_mapping_error(dev, *dma_addr)) {
@@ -319,7 +308,6 @@ static int ib_umem_odp_map_dma_single_page(
 		return -EFAULT;
 	}
 	umem_odp->npages++;
-	*dma_addr |= access_mask;
 	return 0;
 }
 
@@ -355,9 +343,6 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
 	struct hmm_range range = {};
 	unsigned long timeout;
 
-	if (access_mask == 0)
-		return -EINVAL;
-
 	if (user_virt < ib_umem_start(umem_odp) ||
 	    user_virt + bcnt > ib_umem_end(umem_odp))
 		return -EFAULT;
@@ -383,7 +368,7 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
 	if (fault) {
 		range.default_flags = HMM_PFN_REQ_FAULT;
 
-		if (access_mask & ODP_WRITE_ALLOWED_BIT)
+		if (access_mask & HMM_PFN_WRITE)
 			range.default_flags |= HMM_PFN_REQ_WRITE;
 	}
 
@@ -415,22 +400,17 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
 	for (pfn_index = 0; pfn_index < num_pfns;
 		pfn_index += 1 << (page_shift - PAGE_SHIFT), dma_index++) {
 
-		if (fault) {
-			/*
-			 * Since we asked for hmm_range_fault() to populate
-			 * pages it shouldn't return an error entry on success.
-			 */
-			WARN_ON(range.hmm_pfns[pfn_index] & HMM_PFN_ERROR);
-			WARN_ON(!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID));
-		} else {
-			if (!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID)) {
-				WARN_ON(umem_odp->dma_list[dma_index]);
-				continue;
-			}
-			access_mask = ODP_READ_ALLOWED_BIT;
-			if (range.hmm_pfns[pfn_index] & HMM_PFN_WRITE)
-				access_mask |= ODP_WRITE_ALLOWED_BIT;
-		}
+		/*
+		 * Since we asked for hmm_range_fault() to populate
+		 * pages it shouldn't return an error entry on success.
+		 */
+		WARN_ON(fault && range.hmm_pfns[pfn_index] & HMM_PFN_ERROR);
+		WARN_ON(fault && !(range.hmm_pfns[pfn_index] & HMM_PFN_VALID));
+		if (!(range.hmm_pfns[pfn_index] & HMM_PFN_VALID))
+			continue;
+
+		if (range.hmm_pfns[pfn_index] & HMM_PFN_DMA_MAPPED)
+			continue;
 
 		hmm_order = hmm_pfn_to_map_order(range.hmm_pfns[pfn_index]);
 		/* If a hugepage was detected and ODP wasn't set for, the umem
@@ -445,13 +425,13 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
 		}
 
 		ret = ib_umem_odp_map_dma_single_page(
-				umem_odp, dma_index, hmm_pfn_to_page(range.hmm_pfns[pfn_index]),
-				access_mask);
+				umem_odp, dma_index, hmm_pfn_to_page(range.hmm_pfns[pfn_index]));
 		if (ret < 0) {
 			ibdev_dbg(umem_odp->umem.ibdev,
 				  "ib_umem_odp_map_dma_single_page failed with error %d\n", ret);
 			break;
 		}
+		range.hmm_pfns[pfn_index] |= HMM_PFN_DMA_MAPPED;
 	}
 	/* upon success lock should stay on hold for the callee */
 	if (!ret)
@@ -471,7 +451,6 @@ EXPORT_SYMBOL(ib_umem_odp_map_dma_and_lock);
 void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
 				 u64 bound)
 {
-	dma_addr_t dma_addr;
 	dma_addr_t dma;
 	int idx;
 	u64 addr;
@@ -482,34 +461,35 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
 	virt = max_t(u64, virt, ib_umem_start(umem_odp));
 	bound = min_t(u64, bound, ib_umem_end(umem_odp));
 	for (addr = virt; addr < bound; addr += BIT(umem_odp->page_shift)) {
+		unsigned long pfn_idx = (addr - ib_umem_start(umem_odp)) >> PAGE_SHIFT;
+		struct page *page = hmm_pfn_to_page(umem_odp->pfn_list[pfn_idx]);
+
 		idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift;
 		dma = umem_odp->dma_list[idx];
 
-		/* The access flags guaranteed a valid DMA address in case was NULL */
-		if (dma) {
-			unsigned long pfn_idx = (addr - ib_umem_start(umem_odp)) >> PAGE_SHIFT;
-			struct page *page = hmm_pfn_to_page(umem_odp->pfn_list[pfn_idx]);
-
-			dma_addr = dma & ODP_DMA_ADDR_MASK;
-			ib_dma_unmap_page(dev, dma_addr,
-					  BIT(umem_odp->page_shift),
-					  DMA_BIDIRECTIONAL);
-			if (dma & ODP_WRITE_ALLOWED_BIT) {
-				struct page *head_page = compound_head(page);
-				/*
-				 * set_page_dirty prefers being called with
-				 * the page lock. However, MMU notifiers are
-				 * called sometimes with and sometimes without
-				 * the lock. We rely on the umem_mutex instead
-				 * to prevent other mmu notifiers from
-				 * continuing and allowing the page mapping to
-				 * be removed.
-				 */
-				set_page_dirty(head_page);
-			}
-			umem_odp->dma_list[idx] = 0;
-			umem_odp->npages--;
+		if (!(umem_odp->pfn_list[pfn_idx] & HMM_PFN_VALID))
+			goto clear;
+		if (!(umem_odp->pfn_list[pfn_idx] & HMM_PFN_DMA_MAPPED))
+			goto clear;
+
+		ib_dma_unmap_page(dev, dma, BIT(umem_odp->page_shift),
+				  DMA_BIDIRECTIONAL);
+		if (umem_odp->pfn_list[pfn_idx] & HMM_PFN_WRITE) {
+			struct page *head_page = compound_head(page);
+			/*
+			 * set_page_dirty prefers being called with
+			 * the page lock. However, MMU notifiers are
+			 * called sometimes with and sometimes without
+			 * the lock. We rely on the umem_mutex instead
+			 * to prevent other mmu notifiers from
+			 * continuing and allowing the page mapping to
+			 * be removed.
+			 */
+			set_page_dirty(head_page);
 		}
+		umem_odp->npages--;
+clear:
+		umem_odp->pfn_list[pfn_idx] &= ~HMM_PFN_FLAGS;
 	}
 }
 EXPORT_SYMBOL(ib_umem_odp_unmap_dma_pages);
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 23fd72f7f63d..3e4aaa6319db 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -336,6 +336,7 @@ struct mlx5_ib_flow_db {
 #define MLX5_IB_UPD_XLT_PD	      BIT(4)
 #define MLX5_IB_UPD_XLT_ACCESS	      BIT(5)
 #define MLX5_IB_UPD_XLT_INDIRECT      BIT(6)
+#define MLX5_IB_UPD_XLT_DOWNGRADE     BIT(7)
 
 /* Private QP creation flags to be passed in ib_qp_init_attr.create_flags.
  *
diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index 4b37446758fd..78887500ce15 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -34,6 +34,7 @@
 #include <linux/kernel.h>
 #include <linux/dma-buf.h>
 #include <linux/dma-resv.h>
+#include <linux/hmm.h>
 
 #include "mlx5_ib.h"
 #include "cmd.h"
@@ -158,22 +159,12 @@ static void populate_klm(struct mlx5_klm *pklm, size_t idx, size_t nentries,
 	}
 }
 
-static u64 umem_dma_to_mtt(dma_addr_t umem_dma)
-{
-	u64 mtt_entry = umem_dma & ODP_DMA_ADDR_MASK;
-
-	if (umem_dma & ODP_READ_ALLOWED_BIT)
-		mtt_entry |= MLX5_IB_MTT_READ;
-	if (umem_dma & ODP_WRITE_ALLOWED_BIT)
-		mtt_entry |= MLX5_IB_MTT_WRITE;
-
-	return mtt_entry;
-}
-
 static void populate_mtt(__be64 *pas, size_t idx, size_t nentries,
 			 struct mlx5_ib_mr *mr, int flags)
 {
 	struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
+	bool downgrade = flags & MLX5_IB_UPD_XLT_DOWNGRADE;
+	unsigned long pfn;
 	dma_addr_t pa;
 	size_t i;
 
@@ -181,8 +172,17 @@ static void populate_mtt(__be64 *pas, size_t idx, size_t nentries,
 		return;
 
 	for (i = 0; i < nentries; i++) {
+		pfn = odp->pfn_list[idx + i];
+		if (!(pfn & HMM_PFN_VALID))
+			/* ODP initialization */
+			continue;
+
 		pa = odp->dma_list[idx + i];
-		pas[i] = cpu_to_be64(umem_dma_to_mtt(pa));
+		pa |= MLX5_IB_MTT_READ;
+		if ((pfn & HMM_PFN_WRITE) && !downgrade)
+			pa |= MLX5_IB_MTT_WRITE;
+
+		pas[i] = cpu_to_be64(pa);
 	}
 }
 
@@ -286,8 +286,7 @@ static bool mlx5_ib_invalidate_range(struct mmu_interval_notifier *mni,
 		 * estimate the cost of another UMR vs. the cost of bigger
 		 * UMR.
 		 */
-		if (umem_odp->dma_list[idx] &
-		    (ODP_READ_ALLOWED_BIT | ODP_WRITE_ALLOWED_BIT)) {
+		if (umem_odp->pfn_list[idx] & HMM_PFN_VALID) {
 			if (!in_block) {
 				blk_start_idx = idx;
 				in_block = 1;
@@ -668,7 +667,7 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct ib_umem_odp *odp,
 {
 	int page_shift, ret, np;
 	bool downgrade = flags & MLX5_PF_FLAGS_DOWNGRADE;
-	u64 access_mask;
+	u64 access_mask = 0;
 	u64 start_idx;
 	bool fault = !(flags & MLX5_PF_FLAGS_SNAPSHOT);
 	u32 xlt_flags = MLX5_IB_UPD_XLT_ATOMIC;
@@ -676,12 +675,14 @@ static int pagefault_real_mr(struct mlx5_ib_mr *mr, struct ib_umem_odp *odp,
 	if (flags & MLX5_PF_FLAGS_ENABLE)
 		xlt_flags |= MLX5_IB_UPD_XLT_ENABLE;
 
+	if (flags & MLX5_PF_FLAGS_DOWNGRADE)
+		xlt_flags |= MLX5_IB_UPD_XLT_DOWNGRADE;
+
 	page_shift = odp->page_shift;
 	start_idx = (user_va - ib_umem_start(odp)) >> page_shift;
-	access_mask = ODP_READ_ALLOWED_BIT;
 
 	if (odp->umem.writable && !downgrade)
-		access_mask |= ODP_WRITE_ALLOWED_BIT;
+		access_mask |= HMM_PFN_WRITE;
 
 	np = ib_umem_odp_map_dma_and_lock(odp, user_va, bcnt, access_mask, fault);
 	if (np < 0)
diff --git a/include/rdma/ib_umem_odp.h b/include/rdma/ib_umem_odp.h
index 0844c1d05ac6..a345c26a745d 100644
--- a/include/rdma/ib_umem_odp.h
+++ b/include/rdma/ib_umem_odp.h
@@ -8,6 +8,7 @@
 
 #include <rdma/ib_umem.h>
 #include <rdma/ib_verbs.h>
+#include <linux/hmm.h>
 
 struct ib_umem_odp {
 	struct ib_umem umem;
@@ -67,19 +68,6 @@ static inline size_t ib_umem_odp_num_pages(struct ib_umem_odp *umem_odp)
 	       umem_odp->page_shift;
 }
 
-/*
- * The lower 2 bits of the DMA address signal the R/W permissions for
- * the entry. To upgrade the permissions, provide the appropriate
- * bitmask to the map_dma_pages function.
- *
- * Be aware that upgrading a mapped address might result in change of
- * the DMA address for the page.
- */
-#define ODP_READ_ALLOWED_BIT  (1<<0ULL)
-#define ODP_WRITE_ALLOWED_BIT (1<<1ULL)
-
-#define ODP_DMA_ADDR_MASK (~(ODP_READ_ALLOWED_BIT | ODP_WRITE_ALLOWED_BIT))
-
 #ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
 
 struct ib_umem_odp *
-- 
2.46.2

[PATCH 13/18] RDMA/core: Convert UMEM ODP DMA mapping to caching IOVA and page linkage

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

Reuse newly added DMA API to cache IOVA and only link/unlink pages
in fast path for UMEM ODP flow.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/infiniband/core/umem_odp.c   | 101 ++++++---------------------
 drivers/infiniband/hw/mlx5/mlx5_ib.h |  11 +--
 drivers/infiniband/hw/mlx5/odp.c     |  40 +++++++----
 drivers/infiniband/hw/mlx5/umr.c     |  12 +++-
 include/rdma/ib_umem_odp.h           |  13 +---
 5 files changed, 69 insertions(+), 108 deletions(-)

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 9dba369365af..30cd8f353476 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -41,6 +41,7 @@
 #include <linux/hugetlb.h>
 #include <linux/interval_tree.h>
 #include <linux/hmm.h>
+#include <linux/hmm-dma.h>
 #include <linux/pagemap.h>
 
 #include <rdma/ib_umem_odp.h>
@@ -50,6 +51,7 @@
 static inline int ib_init_umem_odp(struct ib_umem_odp *umem_odp,
 				   const struct mmu_interval_notifier_ops *ops)
 {
+	struct ib_device *dev = umem_odp->umem.ibdev;
 	int ret;
 
 	umem_odp->umem.is_odp = 1;
@@ -59,7 +61,6 @@ static inline int ib_init_umem_odp(struct ib_umem_odp *umem_odp,
 		size_t page_size = 1UL << umem_odp->page_shift;
 		unsigned long start;
 		unsigned long end;
-		size_t ndmas, npfns;
 
 		start = ALIGN_DOWN(umem_odp->umem.address, page_size);
 		if (check_add_overflow(umem_odp->umem.address,
@@ -70,36 +71,23 @@ static inline int ib_init_umem_odp(struct ib_umem_odp *umem_odp,
 		if (unlikely(end < page_size))
 			return -EOVERFLOW;
 
-		ndmas = (end - start) >> umem_odp->page_shift;
-		if (!ndmas)
-			return -EINVAL;
-
-		npfns = (end - start) >> PAGE_SHIFT;
-		umem_odp->pfn_list = kvcalloc(
-			npfns, sizeof(*umem_odp->pfn_list), GFP_KERNEL);
-		if (!umem_odp->pfn_list)
-			return -ENOMEM;
-
-		umem_odp->dma_list = kvcalloc(
-			ndmas, sizeof(*umem_odp->dma_list), GFP_KERNEL);
-		if (!umem_odp->dma_list) {
-			ret = -ENOMEM;
-			goto out_pfn_list;
-		}
+		ret = hmm_dma_map_alloc(dev->dma_device, &umem_odp->map,
+					(end - start) >> PAGE_SHIFT,
+					1 << umem_odp->page_shift);
+		if (ret)
+			return ret;
 
 		ret = mmu_interval_notifier_insert(&umem_odp->notifier,
 						   umem_odp->umem.owning_mm,
 						   start, end - start, ops);
 		if (ret)
-			goto out_dma_list;
+			goto out_free_map;
 	}
 
 	return 0;
 
-out_dma_list:
-	kvfree(umem_odp->dma_list);
-out_pfn_list:
-	kvfree(umem_odp->pfn_list);
+out_free_map:
+	hmm_dma_map_free(dev->dma_device, &umem_odp->map);
 	return ret;
 }
 
@@ -262,6 +250,8 @@ EXPORT_SYMBOL(ib_umem_odp_get);
 
 void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
 {
+	struct ib_device *dev = umem_odp->umem.ibdev;
+
 	/*
 	 * Ensure that no more pages are mapped in the umem.
 	 *
@@ -274,48 +264,17 @@ void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
 					    ib_umem_end(umem_odp));
 		mutex_unlock(&umem_odp->umem_mutex);
 		mmu_interval_notifier_remove(&umem_odp->notifier);
-		kvfree(umem_odp->dma_list);
-		kvfree(umem_odp->pfn_list);
+		hmm_dma_map_free(dev->dma_device, &umem_odp->map);
 	}
 	put_pid(umem_odp->tgid);
 	kfree(umem_odp);
 }
 EXPORT_SYMBOL(ib_umem_odp_release);
 
-/*
- * Map for DMA and insert a single page into the on-demand paging page tables.
- *
- * @umem: the umem to insert the page to.
- * @dma_index: index in the umem to add the dma to.
- * @page: the page struct to map and add.
- * @access_mask: access permissions needed for this page.
- *
- * The function returns -EFAULT if the DMA mapping operation fails.
- *
- */
-static int ib_umem_odp_map_dma_single_page(
-		struct ib_umem_odp *umem_odp,
-		unsigned int dma_index,
-		struct page *page)
-{
-	struct ib_device *dev = umem_odp->umem.ibdev;
-	dma_addr_t *dma_addr = &umem_odp->dma_list[dma_index];
-
-	*dma_addr = ib_dma_map_page(dev, page, 0, 1 << umem_odp->page_shift,
-				    DMA_BIDIRECTIONAL);
-	if (ib_dma_mapping_error(dev, *dma_addr)) {
-		*dma_addr = 0;
-		return -EFAULT;
-	}
-	umem_odp->npages++;
-	return 0;
-}
-
 /**
  * ib_umem_odp_map_dma_and_lock - DMA map userspace memory in an ODP MR and lock it.
  *
  * Maps the range passed in the argument to DMA addresses.
- * The DMA addresses of the mapped pages is updated in umem_odp->dma_list.
  * Upon success the ODP MR will be locked to let caller complete its device
  * page table update.
  *
@@ -372,7 +331,7 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
 			range.default_flags |= HMM_PFN_REQ_WRITE;
 	}
 
-	range.hmm_pfns = &(umem_odp->pfn_list[pfn_start_idx]);
+	range.hmm_pfns = &(umem_odp->map.pfn_list[pfn_start_idx]);
 	timeout = jiffies + msecs_to_jiffies(HMM_RANGE_DEFAULT_TIMEOUT);
 
 retry:
@@ -423,15 +382,6 @@ int ib_umem_odp_map_dma_and_lock(struct ib_umem_odp *umem_odp, u64 user_virt,
 				  __func__, hmm_order, page_shift);
 			break;
 		}
-
-		ret = ib_umem_odp_map_dma_single_page(
-				umem_odp, dma_index, hmm_pfn_to_page(range.hmm_pfns[pfn_index]));
-		if (ret < 0) {
-			ibdev_dbg(umem_odp->umem.ibdev,
-				  "ib_umem_odp_map_dma_single_page failed with error %d\n", ret);
-			break;
-		}
-		range.hmm_pfns[pfn_index] |= HMM_PFN_DMA_MAPPED;
 	}
 	/* upon success lock should stay on hold for the callee */
 	if (!ret)
@@ -451,30 +401,23 @@ EXPORT_SYMBOL(ib_umem_odp_map_dma_and_lock);
 void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
 				 u64 bound)
 {
-	dma_addr_t dma;
-	int idx;
-	u64 addr;
 	struct ib_device *dev = umem_odp->umem.ibdev;
+	u64 addr;
 
 	lockdep_assert_held(&umem_odp->umem_mutex);
 
 	virt = max_t(u64, virt, ib_umem_start(umem_odp));
 	bound = min_t(u64, bound, ib_umem_end(umem_odp));
 	for (addr = virt; addr < bound; addr += BIT(umem_odp->page_shift)) {
-		unsigned long pfn_idx = (addr - ib_umem_start(umem_odp)) >> PAGE_SHIFT;
-		struct page *page = hmm_pfn_to_page(umem_odp->pfn_list[pfn_idx]);
-
-		idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift;
-		dma = umem_odp->dma_list[idx];
+		u64 offset = addr - ib_umem_start(umem_odp);
+		size_t idx = offset >> umem_odp->page_shift;
+		unsigned long pfn = umem_odp->map.pfn_list[idx];
 
-		if (!(umem_odp->pfn_list[pfn_idx] & HMM_PFN_VALID))
-			goto clear;
-		if (!(umem_odp->pfn_list[pfn_idx] & HMM_PFN_DMA_MAPPED))
+		if (!hmm_dma_unmap_pfn(dev->dma_device, &umem_odp->map, idx))
 			goto clear;
 
-		ib_dma_unmap_page(dev, dma, BIT(umem_odp->page_shift),
-				  DMA_BIDIRECTIONAL);
-		if (umem_odp->pfn_list[pfn_idx] & HMM_PFN_WRITE) {
+		if (pfn & HMM_PFN_WRITE) {
+			struct page *page = hmm_pfn_to_page(pfn);
 			struct page *head_page = compound_head(page);
 			/*
 			 * set_page_dirty prefers being called with
@@ -489,7 +432,7 @@ void ib_umem_odp_unmap_dma_pages(struct ib_umem_odp *umem_odp, u64 virt,
 		}
 		umem_odp->npages--;
 clear:
-		umem_odp->pfn_list[pfn_idx] &= ~HMM_PFN_FLAGS;
+		umem_odp->map.pfn_list[idx] &= ~HMM_PFN_FLAGS;
 	}
 }
 EXPORT_SYMBOL(ib_umem_odp_unmap_dma_pages);
diff --git a/drivers/infiniband/hw/mlx5/mlx5_ib.h b/drivers/infiniband/hw/mlx5/mlx5_ib.h
index 3e4aaa6319db..1bae5595c729 100644
--- a/drivers/infiniband/hw/mlx5/mlx5_ib.h
+++ b/drivers/infiniband/hw/mlx5/mlx5_ib.h
@@ -1444,8 +1444,8 @@ void mlx5_ib_odp_cleanup_one(struct mlx5_ib_dev *ibdev);
 int __init mlx5_ib_odp_init(void);
 void mlx5_ib_odp_cleanup(void);
 int mlx5_odp_init_mkey_cache(struct mlx5_ib_dev *dev);
-void mlx5_odp_populate_xlt(void *xlt, size_t idx, size_t nentries,
-			   struct mlx5_ib_mr *mr, int flags);
+int mlx5_odp_populate_xlt(void *xlt, size_t idx, size_t nentries,
+			  struct mlx5_ib_mr *mr, int flags);
 
 int mlx5_ib_advise_mr_prefetch(struct ib_pd *pd,
 			       enum ib_uverbs_advise_mr_advice advice,
@@ -1466,8 +1466,11 @@ static inline int mlx5_odp_init_mkey_cache(struct mlx5_ib_dev *dev)
 {
 	return 0;
 }
-static inline void mlx5_odp_populate_xlt(void *xlt, size_t idx, size_t nentries,
-					 struct mlx5_ib_mr *mr, int flags) {}
+static inline int mlx5_odp_populate_xlt(void *xlt, size_t idx, size_t nentries,
+					struct mlx5_ib_mr *mr, int flags)
+{
+	return -EOPNOTSUPP;
+}
 
 static inline int
 mlx5_ib_advise_mr_prefetch(struct ib_pd *pd,
diff --git a/drivers/infiniband/hw/mlx5/odp.c b/drivers/infiniband/hw/mlx5/odp.c
index 78887500ce15..fbb2a5670c32 100644
--- a/drivers/infiniband/hw/mlx5/odp.c
+++ b/drivers/infiniband/hw/mlx5/odp.c
@@ -35,6 +35,8 @@
 #include <linux/dma-buf.h>
 #include <linux/dma-resv.h>
 #include <linux/hmm.h>
+#include <linux/hmm-dma.h>
+#include <linux/pci-p2pdma.h>
 
 #include "mlx5_ib.h"
 #include "cmd.h"
@@ -159,40 +161,50 @@ static void populate_klm(struct mlx5_klm *pklm, size_t idx, size_t nentries,
 	}
 }
 
-static void populate_mtt(__be64 *pas, size_t idx, size_t nentries,
-			 struct mlx5_ib_mr *mr, int flags)
+static int populate_mtt(__be64 *pas, size_t start, size_t nentries,
+			struct mlx5_ib_mr *mr, int flags)
 {
 	struct ib_umem_odp *odp = to_ib_umem_odp(mr->umem);
 	bool downgrade = flags & MLX5_IB_UPD_XLT_DOWNGRADE;
-	unsigned long pfn;
-	dma_addr_t pa;
+	struct pci_p2pdma_map_state p2pdma_state = {};
+	struct ib_device *dev = odp->umem.ibdev;
 	size_t i;
 
 	if (flags & MLX5_IB_UPD_XLT_ZAP)
-		return;
+		return 0;
 
 	for (i = 0; i < nentries; i++) {
-		pfn = odp->pfn_list[idx + i];
+		unsigned long pfn = odp->map.pfn_list[start + i];
+		dma_addr_t dma_addr;
+
+		pfn = odp->map.pfn_list[start + i];
 		if (!(pfn & HMM_PFN_VALID))
 			/* ODP initialization */
 			continue;
 
-		pa = odp->dma_list[idx + i];
-		pa |= MLX5_IB_MTT_READ;
+		dma_addr = hmm_dma_map_pfn(dev->dma_device, &odp->map,
+					   start + i, &p2pdma_state);
+		if (ib_dma_mapping_error(dev, dma_addr))
+			return -EFAULT;
+
+		dma_addr |= MLX5_IB_MTT_READ;
 		if ((pfn & HMM_PFN_WRITE) && !downgrade)
-			pa |= MLX5_IB_MTT_WRITE;
+			dma_addr |= MLX5_IB_MTT_WRITE;
 
-		pas[i] = cpu_to_be64(pa);
+		pas[i] = cpu_to_be64(dma_addr);
+		odp->npages++;
 	}
+	return 0;
 }
 
-void mlx5_odp_populate_xlt(void *xlt, size_t idx, size_t nentries,
-			   struct mlx5_ib_mr *mr, int flags)
+int mlx5_odp_populate_xlt(void *xlt, size_t idx, size_t nentries,
+			  struct mlx5_ib_mr *mr, int flags)
 {
 	if (flags & MLX5_IB_UPD_XLT_INDIRECT) {
 		populate_klm(xlt, idx, nentries, mr, flags);
+		return 0;
 	} else {
-		populate_mtt(xlt, idx, nentries, mr, flags);
+		return populate_mtt(xlt, idx, nentries, mr, flags);
 	}
 }
 
@@ -286,7 +298,7 @@ static bool mlx5_ib_invalidate_range(struct mmu_interval_notifier *mni,
 		 * estimate the cost of another UMR vs. the cost of bigger
 		 * UMR.
 		 */
-		if (umem_odp->pfn_list[idx] & HMM_PFN_VALID) {
+		if (umem_odp->map.pfn_list[idx] & HMM_PFN_VALID) {
 			if (!in_block) {
 				blk_start_idx = idx;
 				in_block = 1;
diff --git a/drivers/infiniband/hw/mlx5/umr.c b/drivers/infiniband/hw/mlx5/umr.c
index 887fd6fa3ba9..d7fa94ab23cf 100644
--- a/drivers/infiniband/hw/mlx5/umr.c
+++ b/drivers/infiniband/hw/mlx5/umr.c
@@ -811,7 +811,17 @@ int mlx5r_umr_update_xlt(struct mlx5_ib_mr *mr, u64 idx, int npages,
 		size_to_map = npages * desc_size;
 		dma_sync_single_for_cpu(ddev, sg.addr, sg.length,
 					DMA_TO_DEVICE);
-		mlx5_odp_populate_xlt(xlt, idx, npages, mr, flags);
+		/*
+		 * npages is the maximum number of pages to map, but we
+		 * can't guarantee that all pages are actually mapped.
+		 *
+		 * For example, if page is p2p of type which is not supported
+		 * for mapping, the number of pages mapped will be less than
+		 * requested.
+		 */
+		err = mlx5_odp_populate_xlt(xlt, idx, npages, mr, flags);
+		if (err)
+			return err;
 		dma_sync_single_for_device(ddev, sg.addr, sg.length,
 					   DMA_TO_DEVICE);
 		sg.length = ALIGN(size_to_map, MLX5_UMR_FLEX_ALIGNMENT);
diff --git a/include/rdma/ib_umem_odp.h b/include/rdma/ib_umem_odp.h
index a345c26a745d..2a24bf791c10 100644
--- a/include/rdma/ib_umem_odp.h
+++ b/include/rdma/ib_umem_odp.h
@@ -8,24 +8,17 @@
 
 #include <rdma/ib_umem.h>
 #include <rdma/ib_verbs.h>
-#include <linux/hmm.h>
+#include <linux/hmm-dma.h>
 
 struct ib_umem_odp {
 	struct ib_umem umem;
 	struct mmu_interval_notifier notifier;
 	struct pid *tgid;
 
-	/* An array of the pfns included in the on-demand paging umem. */
-	unsigned long *pfn_list;
+	struct hmm_dma_map map;
 
 	/*
-	 * An array with DMA addresses mapped for pfns in pfn_list.
-	 * The lower two bits designate access permissions.
-	 * See ODP_READ_ALLOWED_BIT and ODP_WRITE_ALLOWED_BIT.
-	 */
-	dma_addr_t		*dma_list;
-	/*
-	 * The umem_mutex protects the page_list and dma_list fields of an ODP
+	 * The umem_mutex protects the page_list field of an ODP
 	 * umem, allowing only a single thread to map/unmap pages. The mutex
 	 * also protects access to the mmu notifier counters.
 	 */
-- 
2.46.2

[PATCH 14/18] RDMA/umem: Separate implicit ODP initialization from explicit ODP

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

Create separate functions for the implicit ODP initialization
which is different from the explicit ODP initialization.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/infiniband/core/umem_odp.c | 91 +++++++++++++++---------------
 1 file changed, 46 insertions(+), 45 deletions(-)

diff --git a/drivers/infiniband/core/umem_odp.c b/drivers/infiniband/core/umem_odp.c
index 30cd8f353476..51d518989914 100644
--- a/drivers/infiniband/core/umem_odp.c
+++ b/drivers/infiniband/core/umem_odp.c
@@ -48,41 +48,44 @@
 
 #include "uverbs.h"
 
-static inline int ib_init_umem_odp(struct ib_umem_odp *umem_odp,
-				   const struct mmu_interval_notifier_ops *ops)
+static void ib_init_umem_implicit_odp(struct ib_umem_odp *umem_odp)
+{
+	umem_odp->is_implicit_odp = 1;
+	umem_odp->umem.is_odp = 1;
+	mutex_init(&umem_odp->umem_mutex);
+}
+
+static int ib_init_umem_odp(struct ib_umem_odp *umem_odp,
+			    const struct mmu_interval_notifier_ops *ops)
 {
 	struct ib_device *dev = umem_odp->umem.ibdev;
+	size_t page_size = 1UL << umem_odp->page_shift;
+	unsigned long start;
+	unsigned long end;
 	int ret;
 
 	umem_odp->umem.is_odp = 1;
 	mutex_init(&umem_odp->umem_mutex);
 
-	if (!umem_odp->is_implicit_odp) {
-		size_t page_size = 1UL << umem_odp->page_shift;
-		unsigned long start;
-		unsigned long end;
-
-		start = ALIGN_DOWN(umem_odp->umem.address, page_size);
-		if (check_add_overflow(umem_odp->umem.address,
-				       (unsigned long)umem_odp->umem.length,
-				       &end))
-			return -EOVERFLOW;
-		end = ALIGN(end, page_size);
-		if (unlikely(end < page_size))
-			return -EOVERFLOW;
-
-		ret = hmm_dma_map_alloc(dev->dma_device, &umem_odp->map,
-					(end - start) >> PAGE_SHIFT,
-					1 << umem_odp->page_shift);
-		if (ret)
-			return ret;
-
-		ret = mmu_interval_notifier_insert(&umem_odp->notifier,
-						   umem_odp->umem.owning_mm,
-						   start, end - start, ops);
-		if (ret)
-			goto out_free_map;
-	}
+	start = ALIGN_DOWN(umem_odp->umem.address, page_size);
+	if (check_add_overflow(umem_odp->umem.address,
+			       (unsigned long)umem_odp->umem.length, &end))
+		return -EOVERFLOW;
+	end = ALIGN(end, page_size);
+	if (unlikely(end < page_size))
+		return -EOVERFLOW;
+
+	ret = hmm_dma_map_alloc(dev->dma_device, &umem_odp->map,
+				(end - start) >> PAGE_SHIFT,
+				1 << umem_odp->page_shift);
+	if (ret)
+		return ret;
+
+	ret = mmu_interval_notifier_insert(&umem_odp->notifier,
+					   umem_odp->umem.owning_mm, start,
+					   end - start, ops);
+	if (ret)
+		goto out_free_map;
 
 	return 0;
 
@@ -106,7 +109,6 @@ struct ib_umem_odp *ib_umem_odp_alloc_implicit(struct ib_device *device,
 {
 	struct ib_umem *umem;
 	struct ib_umem_odp *umem_odp;
-	int ret;
 
 	if (access & IB_ACCESS_HUGETLB)
 		return ERR_PTR(-EINVAL);
@@ -118,16 +120,10 @@ struct ib_umem_odp *ib_umem_odp_alloc_implicit(struct ib_device *device,
 	umem->ibdev = device;
 	umem->writable = ib_access_writable(access);
 	umem->owning_mm = current->mm;
-	umem_odp->is_implicit_odp = 1;
 	umem_odp->page_shift = PAGE_SHIFT;
 
 	umem_odp->tgid = get_task_pid(current->group_leader, PIDTYPE_PID);
-	ret = ib_init_umem_odp(umem_odp, NULL);
-	if (ret) {
-		put_pid(umem_odp->tgid);
-		kfree(umem_odp);
-		return ERR_PTR(ret);
-	}
+	ib_init_umem_implicit_odp(umem_odp);
 	return umem_odp;
 }
 EXPORT_SYMBOL(ib_umem_odp_alloc_implicit);
@@ -248,7 +244,7 @@ struct ib_umem_odp *ib_umem_odp_get(struct ib_device *device,
 }
 EXPORT_SYMBOL(ib_umem_odp_get);
 
-void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
+static void ib_umem_odp_free(struct ib_umem_odp *umem_odp)
 {
 	struct ib_device *dev = umem_odp->umem.ibdev;
 
@@ -258,14 +254,19 @@ void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
 	 * It is the driver's responsibility to ensure, before calling us,
 	 * that the hardware will not attempt to access the MR any more.
 	 */
-	if (!umem_odp->is_implicit_odp) {
-		mutex_lock(&umem_odp->umem_mutex);
-		ib_umem_odp_unmap_dma_pages(umem_odp, ib_umem_start(umem_odp),
-					    ib_umem_end(umem_odp));
-		mutex_unlock(&umem_odp->umem_mutex);
-		mmu_interval_notifier_remove(&umem_odp->notifier);
-		hmm_dma_map_free(dev->dma_device, &umem_odp->map);
-	}
+	mutex_lock(&umem_odp->umem_mutex);
+	ib_umem_odp_unmap_dma_pages(umem_odp, ib_umem_start(umem_odp),
+				    ib_umem_end(umem_odp));
+	mutex_unlock(&umem_odp->umem_mutex);
+	mmu_interval_notifier_remove(&umem_odp->notifier);
+	hmm_dma_map_free(dev->dma_device, &umem_odp->map);
+}
+
+void ib_umem_odp_release(struct ib_umem_odp *umem_odp)
+{
+	if (!umem_odp->is_implicit_odp)
+		ib_umem_odp_free(umem_odp);
+
 	put_pid(umem_odp->tgid);
 	kfree(umem_odp);
 }
-- 
2.46.2

[PATCH 15/18] vfio/mlx5: Explicitly use number of pages instead of allocated length

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

allocated_length is a multiple of page size and number of pages,
so let's change the functions to accept number of pages. It opens
us a venue to combine receive and send paths together with code
readability improvement.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/vfio/pci/mlx5/cmd.c  | 32 ++++++++++-----------
 drivers/vfio/pci/mlx5/cmd.h  | 10 +++----
 drivers/vfio/pci/mlx5/main.c | 56 +++++++++++++++++++++++-------------
 3 files changed, 57 insertions(+), 41 deletions(-)

diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c
index 41a4b0cf4297..fdc3e515741f 100644
--- a/drivers/vfio/pci/mlx5/cmd.c
+++ b/drivers/vfio/pci/mlx5/cmd.c
@@ -318,8 +318,7 @@ static int _create_mkey(struct mlx5_core_dev *mdev, u32 pdn,
 			struct mlx5_vhca_recv_buf *recv_buf,
 			u32 *mkey)
 {
-	size_t npages = buf ? DIV_ROUND_UP(buf->allocated_length, PAGE_SIZE) :
-				recv_buf->npages;
+	size_t npages = buf ? buf->npages : recv_buf->npages;
 	int err = 0, inlen;
 	__be64 *mtt;
 	void *mkc;
@@ -375,7 +374,7 @@ static int mlx5vf_dma_data_buffer(struct mlx5_vhca_data_buffer *buf)
 	if (mvdev->mdev_detach)
 		return -ENOTCONN;
 
-	if (buf->dmaed || !buf->allocated_length)
+	if (buf->dmaed || !buf->npages)
 		return -EINVAL;
 
 	ret = dma_map_sgtable(mdev->device, &buf->table.sgt, buf->dma_dir, 0);
@@ -444,7 +443,7 @@ static int mlx5vf_add_migration_pages(struct mlx5_vhca_data_buffer *buf,
 
 		if (ret)
 			goto err;
-		buf->allocated_length += filled * PAGE_SIZE;
+		buf->npages += filled;
 		/* clean input for another bulk allocation */
 		memset(page_list, 0, filled * sizeof(*page_list));
 		to_fill = min_t(unsigned int, to_alloc,
@@ -460,8 +459,7 @@ static int mlx5vf_add_migration_pages(struct mlx5_vhca_data_buffer *buf,
 }
 
 struct mlx5_vhca_data_buffer *
-mlx5vf_alloc_data_buffer(struct mlx5_vf_migration_file *migf,
-			 size_t length,
+mlx5vf_alloc_data_buffer(struct mlx5_vf_migration_file *migf, u32 npages,
 			 enum dma_data_direction dma_dir)
 {
 	struct mlx5_vhca_data_buffer *buf;
@@ -473,9 +471,8 @@ mlx5vf_alloc_data_buffer(struct mlx5_vf_migration_file *migf,
 
 	buf->dma_dir = dma_dir;
 	buf->migf = migf;
-	if (length) {
-		ret = mlx5vf_add_migration_pages(buf,
-				DIV_ROUND_UP_ULL(length, PAGE_SIZE));
+	if (npages) {
+		ret = mlx5vf_add_migration_pages(buf, npages);
 		if (ret)
 			goto end;
 
@@ -501,8 +498,8 @@ void mlx5vf_put_data_buffer(struct mlx5_vhca_data_buffer *buf)
 }
 
 struct mlx5_vhca_data_buffer *
-mlx5vf_get_data_buffer(struct mlx5_vf_migration_file *migf,
-		       size_t length, enum dma_data_direction dma_dir)
+mlx5vf_get_data_buffer(struct mlx5_vf_migration_file *migf, u32 npages,
+		       enum dma_data_direction dma_dir)
 {
 	struct mlx5_vhca_data_buffer *buf, *temp_buf;
 	struct list_head free_list;
@@ -517,7 +514,7 @@ mlx5vf_get_data_buffer(struct mlx5_vf_migration_file *migf,
 	list_for_each_entry_safe(buf, temp_buf, &migf->avail_list, buf_elm) {
 		if (buf->dma_dir == dma_dir) {
 			list_del_init(&buf->buf_elm);
-			if (buf->allocated_length >= length) {
+			if (buf->npages >= npages) {
 				spin_unlock_irq(&migf->list_lock);
 				goto found;
 			}
@@ -531,7 +528,7 @@ mlx5vf_get_data_buffer(struct mlx5_vf_migration_file *migf,
 		}
 	}
 	spin_unlock_irq(&migf->list_lock);
-	buf = mlx5vf_alloc_data_buffer(migf, length, dma_dir);
+	buf = mlx5vf_alloc_data_buffer(migf, npages, dma_dir);
 
 found:
 	while ((temp_buf = list_first_entry_or_null(&free_list,
@@ -712,7 +709,7 @@ int mlx5vf_cmd_save_vhca_state(struct mlx5vf_pci_core_device *mvdev,
 	MLX5_SET(save_vhca_state_in, in, op_mod, 0);
 	MLX5_SET(save_vhca_state_in, in, vhca_id, mvdev->vhca_id);
 	MLX5_SET(save_vhca_state_in, in, mkey, buf->mkey);
-	MLX5_SET(save_vhca_state_in, in, size, buf->allocated_length);
+	MLX5_SET(save_vhca_state_in, in, size, buf->npages * PAGE_SIZE);
 	MLX5_SET(save_vhca_state_in, in, incremental, inc);
 	MLX5_SET(save_vhca_state_in, in, set_track, track);
 
@@ -734,8 +731,11 @@ int mlx5vf_cmd_save_vhca_state(struct mlx5vf_pci_core_device *mvdev,
 	}
 
 	if (!header_buf) {
-		header_buf = mlx5vf_get_data_buffer(migf,
-			sizeof(struct mlx5_vf_migration_header), DMA_NONE);
+		header_buf = mlx5vf_get_data_buffer(
+			migf,
+			DIV_ROUND_UP(sizeof(struct mlx5_vf_migration_header),
+				     PAGE_SIZE),
+			DMA_NONE);
 		if (IS_ERR(header_buf)) {
 			err = PTR_ERR(header_buf);
 			goto err_free;
diff --git a/drivers/vfio/pci/mlx5/cmd.h b/drivers/vfio/pci/mlx5/cmd.h
index df421dc6de04..7d4a833b6900 100644
--- a/drivers/vfio/pci/mlx5/cmd.h
+++ b/drivers/vfio/pci/mlx5/cmd.h
@@ -56,7 +56,7 @@ struct mlx5_vhca_data_buffer {
 	struct sg_append_table table;
 	loff_t start_pos;
 	u64 length;
-	u64 allocated_length;
+	u32 npages;
 	u32 mkey;
 	enum dma_data_direction dma_dir;
 	u8 dmaed:1;
@@ -217,12 +217,12 @@ int mlx5vf_cmd_alloc_pd(struct mlx5_vf_migration_file *migf);
 void mlx5vf_cmd_dealloc_pd(struct mlx5_vf_migration_file *migf);
 void mlx5fv_cmd_clean_migf_resources(struct mlx5_vf_migration_file *migf);
 struct mlx5_vhca_data_buffer *
-mlx5vf_alloc_data_buffer(struct mlx5_vf_migration_file *migf,
-			 size_t length, enum dma_data_direction dma_dir);
+mlx5vf_alloc_data_buffer(struct mlx5_vf_migration_file *migf, u32 npages,
+			 enum dma_data_direction dma_dir);
 void mlx5vf_free_data_buffer(struct mlx5_vhca_data_buffer *buf);
 struct mlx5_vhca_data_buffer *
-mlx5vf_get_data_buffer(struct mlx5_vf_migration_file *migf,
-		       size_t length, enum dma_data_direction dma_dir);
+mlx5vf_get_data_buffer(struct mlx5_vf_migration_file *migf, u32 npages,
+		       enum dma_data_direction dma_dir);
 void mlx5vf_put_data_buffer(struct mlx5_vhca_data_buffer *buf);
 struct page *mlx5vf_get_migration_page(struct mlx5_vhca_data_buffer *buf,
 				       unsigned long offset);
diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
index 242c23eef452..a1dbee3be1e0 100644
--- a/drivers/vfio/pci/mlx5/main.c
+++ b/drivers/vfio/pci/mlx5/main.c
@@ -308,6 +308,7 @@ static struct mlx5_vhca_data_buffer *
 mlx5vf_mig_file_get_stop_copy_buf(struct mlx5_vf_migration_file *migf,
 				  u8 index, size_t required_length)
 {
+	u32 npages = DIV_ROUND_UP(required_length, PAGE_SIZE);
 	struct mlx5_vhca_data_buffer *buf = migf->buf[index];
 	u8 chunk_num;
 
@@ -315,12 +316,11 @@ mlx5vf_mig_file_get_stop_copy_buf(struct mlx5_vf_migration_file *migf,
 	chunk_num = buf->stop_copy_chunk_num;
 	buf->migf->buf[index] = NULL;
 	/* Checking whether the pre-allocated buffer can fit */
-	if (buf->allocated_length >= required_length)
+	if (buf->npages >= npages)
 		return buf;
 
 	mlx5vf_put_data_buffer(buf);
-	buf = mlx5vf_get_data_buffer(buf->migf, required_length,
-				     DMA_FROM_DEVICE);
+	buf = mlx5vf_get_data_buffer(buf->migf, npages, DMA_FROM_DEVICE);
 	if (IS_ERR(buf))
 		return buf;
 
@@ -373,7 +373,8 @@ static int mlx5vf_add_stop_copy_header(struct mlx5_vf_migration_file *migf,
 	u8 *to_buff;
 	int ret;
 
-	header_buf = mlx5vf_get_data_buffer(migf, size, DMA_NONE);
+	header_buf = mlx5vf_get_data_buffer(migf, DIV_ROUND_UP(size, PAGE_SIZE),
+					    DMA_NONE);
 	if (IS_ERR(header_buf))
 		return PTR_ERR(header_buf);
 
@@ -388,7 +389,7 @@ static int mlx5vf_add_stop_copy_header(struct mlx5_vf_migration_file *migf,
 	to_buff = kmap_local_page(page);
 	memcpy(to_buff, &header, sizeof(header));
 	header_buf->length = sizeof(header);
-	data.stop_copy_size = cpu_to_le64(migf->buf[0]->allocated_length);
+	data.stop_copy_size = cpu_to_le64(migf->buf[0]->npages * PAGE_SIZE);
 	memcpy(to_buff + sizeof(header), &data, sizeof(data));
 	header_buf->length += sizeof(data);
 	kunmap_local(to_buff);
@@ -437,15 +438,20 @@ static int mlx5vf_prep_stop_copy(struct mlx5vf_pci_core_device *mvdev,
 
 	num_chunks = mvdev->chunk_mode ? MAX_NUM_CHUNKS : 1;
 	for (i = 0; i < num_chunks; i++) {
-		buf = mlx5vf_get_data_buffer(migf, inc_state_size, DMA_FROM_DEVICE);
+		buf = mlx5vf_get_data_buffer(
+			migf, DIV_ROUND_UP(inc_state_size, PAGE_SIZE),
+			DMA_FROM_DEVICE);
 		if (IS_ERR(buf)) {
 			ret = PTR_ERR(buf);
 			goto err;
 		}
 
 		migf->buf[i] = buf;
-		buf = mlx5vf_get_data_buffer(migf,
-				sizeof(struct mlx5_vf_migration_header), DMA_NONE);
+		buf = mlx5vf_get_data_buffer(
+			migf,
+			DIV_ROUND_UP(sizeof(struct mlx5_vf_migration_header),
+				     PAGE_SIZE),
+			DMA_NONE);
 		if (IS_ERR(buf)) {
 			ret = PTR_ERR(buf);
 			goto err;
@@ -553,7 +559,8 @@ static long mlx5vf_precopy_ioctl(struct file *filp, unsigned int cmd,
 	 * We finished transferring the current state and the device has a
 	 * dirty state, save a new state to be ready for.
 	 */
-	buf = mlx5vf_get_data_buffer(migf, inc_length, DMA_FROM_DEVICE);
+	buf = mlx5vf_get_data_buffer(migf, DIV_ROUND_UP(inc_length, PAGE_SIZE),
+				     DMA_FROM_DEVICE);
 	if (IS_ERR(buf)) {
 		ret = PTR_ERR(buf);
 		mlx5vf_mark_err(migf);
@@ -673,8 +680,8 @@ mlx5vf_pci_save_device_data(struct mlx5vf_pci_core_device *mvdev, bool track)
 
 	if (track) {
 		/* leave the allocated buffer ready for the stop-copy phase */
-		buf = mlx5vf_alloc_data_buffer(migf,
-			migf->buf[0]->allocated_length, DMA_FROM_DEVICE);
+		buf = mlx5vf_alloc_data_buffer(migf, migf->buf[0]->npages,
+					       DMA_FROM_DEVICE);
 		if (IS_ERR(buf)) {
 			ret = PTR_ERR(buf);
 			goto out_pd;
@@ -917,11 +924,14 @@ static ssize_t mlx5vf_resume_write(struct file *filp, const char __user *buf,
 				goto out_unlock;
 			break;
 		case MLX5_VF_LOAD_STATE_PREP_HEADER_DATA:
-			if (vhca_buf_header->allocated_length < migf->record_size) {
+		{
+			u32 npages = DIV_ROUND_UP(migf->record_size, PAGE_SIZE);
+
+			if (vhca_buf_header->npages < npages) {
 				mlx5vf_free_data_buffer(vhca_buf_header);
 
-				migf->buf_header[0] = mlx5vf_alloc_data_buffer(migf,
-						migf->record_size, DMA_NONE);
+				migf->buf_header[0] = mlx5vf_alloc_data_buffer(
+					migf, npages, DMA_NONE);
 				if (IS_ERR(migf->buf_header[0])) {
 					ret = PTR_ERR(migf->buf_header[0]);
 					migf->buf_header[0] = NULL;
@@ -934,6 +944,7 @@ static ssize_t mlx5vf_resume_write(struct file *filp, const char __user *buf,
 			vhca_buf_header->start_pos = migf->max_pos;
 			migf->load_state = MLX5_VF_LOAD_STATE_READ_HEADER_DATA;
 			break;
+		}
 		case MLX5_VF_LOAD_STATE_READ_HEADER_DATA:
 			ret = mlx5vf_resume_read_header_data(migf, vhca_buf_header,
 							&buf, &len, pos, &done);
@@ -944,12 +955,13 @@ static ssize_t mlx5vf_resume_write(struct file *filp, const char __user *buf,
 		{
 			u64 size = max(migf->record_size,
 				       migf->stop_copy_prep_size);
+			u32 npages = DIV_ROUND_UP(size, PAGE_SIZE);
 
-			if (vhca_buf->allocated_length < size) {
+			if (vhca_buf->npages < npages) {
 				mlx5vf_free_data_buffer(vhca_buf);
 
-				migf->buf[0] = mlx5vf_alloc_data_buffer(migf,
-							size, DMA_TO_DEVICE);
+				migf->buf[0] = mlx5vf_alloc_data_buffer(
+					migf, npages, DMA_TO_DEVICE);
 				if (IS_ERR(migf->buf[0])) {
 					ret = PTR_ERR(migf->buf[0]);
 					migf->buf[0] = NULL;
@@ -1031,8 +1043,11 @@ mlx5vf_pci_resume_device_data(struct mlx5vf_pci_core_device *mvdev)
 	}
 
 	migf->buf[0] = buf;
-	buf = mlx5vf_alloc_data_buffer(migf,
-		sizeof(struct mlx5_vf_migration_header), DMA_NONE);
+	buf = mlx5vf_alloc_data_buffer(
+		migf,
+		DIV_ROUND_UP(sizeof(struct mlx5_vf_migration_header),
+			     PAGE_SIZE),
+		DMA_NONE);
 	if (IS_ERR(buf)) {
 		ret = PTR_ERR(buf);
 		goto out_buf;
@@ -1149,7 +1164,8 @@ mlx5vf_pci_step_device_state_locked(struct mlx5vf_pci_core_device *mvdev,
 					MLX5VF_QUERY_INC | MLX5VF_QUERY_CLEANUP);
 		if (ret)
 			return ERR_PTR(ret);
-		buf = mlx5vf_get_data_buffer(migf, size, DMA_FROM_DEVICE);
+		buf = mlx5vf_get_data_buffer(migf,
+				DIV_ROUND_UP(size, PAGE_SIZE), DMA_FROM_DEVICE);
 		if (IS_ERR(buf))
 			return ERR_CAST(buf);
 		/* pre_copy cleanup */
-- 
2.46.2

[PATCH 16/18] vfio/mlx5: Rewrite create mkey flow to allow better code reuse

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

Change the creation of mkey to be performed in multiple steps:
data allocation, DMA setup and actual call to HW to create that mkey.

In this new flow, the whole input to MKEY command is saved to eliminate
the need to keep array of pointers for DMA addresses for receive list
and in the future patches for send list too.

In addition to memory size reduce and elimination of unnecessary data
movements to set MKEY input, the code is prepared for future reuse.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/vfio/pci/mlx5/cmd.c | 156 ++++++++++++++++++++----------------
 drivers/vfio/pci/mlx5/cmd.h |   4 +-
 2 files changed, 90 insertions(+), 70 deletions(-)

diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c
index fdc3e515741f..1832a6c1f35d 100644
--- a/drivers/vfio/pci/mlx5/cmd.c
+++ b/drivers/vfio/pci/mlx5/cmd.c
@@ -313,39 +313,21 @@ static int mlx5vf_cmd_get_vhca_id(struct mlx5_core_dev *mdev, u16 function_id,
 	return ret;
 }
 
-static int _create_mkey(struct mlx5_core_dev *mdev, u32 pdn,
-			struct mlx5_vhca_data_buffer *buf,
-			struct mlx5_vhca_recv_buf *recv_buf,
-			u32 *mkey)
+static u32 *alloc_mkey_in(u32 npages, u32 pdn)
 {
-	size_t npages = buf ? buf->npages : recv_buf->npages;
-	int err = 0, inlen;
-	__be64 *mtt;
+	int inlen;
 	void *mkc;
 	u32 *in;
 
 	inlen = MLX5_ST_SZ_BYTES(create_mkey_in) +
-		sizeof(*mtt) * round_up(npages, 2);
+		sizeof(__be64) * round_up(npages, 2);
 
-	in = kvzalloc(inlen, GFP_KERNEL);
+	in = kvzalloc(inlen, GFP_KERNEL_ACCOUNT);
 	if (!in)
-		return -ENOMEM;
+		return NULL;
 
 	MLX5_SET(create_mkey_in, in, translations_octword_actual_size,
 		 DIV_ROUND_UP(npages, 2));
-	mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, in, klm_pas_mtt);
-
-	if (buf) {
-		struct sg_dma_page_iter dma_iter;
-
-		for_each_sgtable_dma_page(&buf->table.sgt, &dma_iter, 0)
-			*mtt++ = cpu_to_be64(sg_page_iter_dma_address(&dma_iter));
-	} else {
-		int i;
-
-		for (i = 0; i < npages; i++)
-			*mtt++ = cpu_to_be64(recv_buf->dma_addrs[i]);
-	}
 
 	mkc = MLX5_ADDR_OF(create_mkey_in, in, memory_key_mkey_entry);
 	MLX5_SET(mkc, mkc, access_mode_1_0, MLX5_MKC_ACCESS_MODE_MTT);
@@ -359,9 +341,29 @@ static int _create_mkey(struct mlx5_core_dev *mdev, u32 pdn,
 	MLX5_SET(mkc, mkc, log_page_size, PAGE_SHIFT);
 	MLX5_SET(mkc, mkc, translations_octword_size, DIV_ROUND_UP(npages, 2));
 	MLX5_SET64(mkc, mkc, len, npages * PAGE_SIZE);
-	err = mlx5_core_create_mkey(mdev, mkey, in, inlen);
-	kvfree(in);
-	return err;
+
+	return in;
+}
+
+static int create_mkey(struct mlx5_core_dev *mdev, u32 npages,
+		       struct mlx5_vhca_data_buffer *buf, u32 *mkey_in,
+		       u32 *mkey)
+{
+	__be64 *mtt;
+	int inlen;
+
+	mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
+	if (buf) {
+		struct sg_dma_page_iter dma_iter;
+
+		for_each_sgtable_dma_page(&buf->table.sgt, &dma_iter, 0)
+			*mtt++ = cpu_to_be64(sg_page_iter_dma_address(&dma_iter));
+	}
+
+	inlen = MLX5_ST_SZ_BYTES(create_mkey_in) +
+		sizeof(__be64) * round_up(npages, 2);
+
+	return mlx5_core_create_mkey(mdev, mkey, mkey_in, inlen);
 }
 
 static int mlx5vf_dma_data_buffer(struct mlx5_vhca_data_buffer *buf)
@@ -374,20 +376,28 @@ static int mlx5vf_dma_data_buffer(struct mlx5_vhca_data_buffer *buf)
 	if (mvdev->mdev_detach)
 		return -ENOTCONN;
 
-	if (buf->dmaed || !buf->npages)
+	if (buf->mkey_in || !buf->npages)
 		return -EINVAL;
 
 	ret = dma_map_sgtable(mdev->device, &buf->table.sgt, buf->dma_dir, 0);
 	if (ret)
 		return ret;
 
-	ret = _create_mkey(mdev, buf->migf->pdn, buf, NULL, &buf->mkey);
-	if (ret)
+	buf->mkey_in = alloc_mkey_in(buf->npages, buf->migf->pdn);
+	if (!buf->mkey_in) {
+		ret = -ENOMEM;
 		goto err;
+	}
 
-	buf->dmaed = true;
+	ret = create_mkey(mdev, buf->npages, buf, buf->mkey_in, &buf->mkey);
+	if (ret)
+		goto err_create_mkey;
 
 	return 0;
+
+err_create_mkey:
+	kvfree(buf->mkey_in);
+	buf->mkey_in = NULL;
 err:
 	dma_unmap_sgtable(mdev->device, &buf->table.sgt, buf->dma_dir, 0);
 	return ret;
@@ -401,8 +411,9 @@ void mlx5vf_free_data_buffer(struct mlx5_vhca_data_buffer *buf)
 	lockdep_assert_held(&migf->mvdev->state_mutex);
 	WARN_ON(migf->mvdev->mdev_detach);
 
-	if (buf->dmaed) {
+	if (buf->mkey_in) {
 		mlx5_core_destroy_mkey(migf->mvdev->mdev, buf->mkey);
+		kvfree(buf->mkey_in);
 		dma_unmap_sgtable(migf->mvdev->mdev->device, &buf->table.sgt,
 				  buf->dma_dir, 0);
 	}
@@ -779,7 +790,7 @@ int mlx5vf_cmd_load_vhca_state(struct mlx5vf_pci_core_device *mvdev,
 	if (mvdev->mdev_detach)
 		return -ENOTCONN;
 
-	if (!buf->dmaed) {
+	if (!buf->mkey_in) {
 		err = mlx5vf_dma_data_buffer(buf);
 		if (err)
 			return err;
@@ -1380,56 +1391,54 @@ static int alloc_recv_pages(struct mlx5_vhca_recv_buf *recv_buf,
 	kvfree(recv_buf->page_list);
 	return -ENOMEM;
 }
+static void unregister_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
+				 u32 *mkey_in)
+{
+	dma_addr_t addr;
+	__be64 *mtt;
+	int i;
+
+	mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
+	for (i = npages - 1; i >= 0; i--) {
+		addr = be64_to_cpu(mtt[i]);
+		dma_unmap_single(mdev->device, addr, PAGE_SIZE,
+				DMA_FROM_DEVICE);
+	}
+}
 
-static int register_dma_recv_pages(struct mlx5_core_dev *mdev,
-				   struct mlx5_vhca_recv_buf *recv_buf)
+static int register_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
+			      struct page **page_list, u32 *mkey_in)
 {
-	int i, j;
+	dma_addr_t addr;
+	__be64 *mtt;
+	int i;
 
-	recv_buf->dma_addrs = kvcalloc(recv_buf->npages,
-				       sizeof(*recv_buf->dma_addrs),
-				       GFP_KERNEL_ACCOUNT);
-	if (!recv_buf->dma_addrs)
-		return -ENOMEM;
+	mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
 
-	for (i = 0; i < recv_buf->npages; i++) {
-		recv_buf->dma_addrs[i] = dma_map_page(mdev->device,
-						      recv_buf->page_list[i],
-						      0, PAGE_SIZE,
-						      DMA_FROM_DEVICE);
-		if (dma_mapping_error(mdev->device, recv_buf->dma_addrs[i]))
+	for (i = 0; i < npages; i++) {
+		addr = dma_map_page(mdev->device, page_list[i], 0, PAGE_SIZE,
+				    DMA_FROM_DEVICE);
+		if (dma_mapping_error(mdev->device, addr))
 			goto error;
+
+		*mtt++ = cpu_to_be64(addr);
 	}
+
 	return 0;
 
 error:
-	for (j = 0; j < i; j++)
-		dma_unmap_single(mdev->device, recv_buf->dma_addrs[j],
-				 PAGE_SIZE, DMA_FROM_DEVICE);
-
-	kvfree(recv_buf->dma_addrs);
+	unregister_dma_pages(mdev, i, mkey_in);
 	return -ENOMEM;
 }
 
-static void unregister_dma_recv_pages(struct mlx5_core_dev *mdev,
-				      struct mlx5_vhca_recv_buf *recv_buf)
-{
-	int i;
-
-	for (i = 0; i < recv_buf->npages; i++)
-		dma_unmap_single(mdev->device, recv_buf->dma_addrs[i],
-				 PAGE_SIZE, DMA_FROM_DEVICE);
-
-	kvfree(recv_buf->dma_addrs);
-}
-
 static void mlx5vf_free_qp_recv_resources(struct mlx5_core_dev *mdev,
 					  struct mlx5_vhca_qp *qp)
 {
 	struct mlx5_vhca_recv_buf *recv_buf = &qp->recv_buf;
 
 	mlx5_core_destroy_mkey(mdev, recv_buf->mkey);
-	unregister_dma_recv_pages(mdev, recv_buf);
+	unregister_dma_pages(mdev, recv_buf->npages, recv_buf->mkey_in);
+	kvfree(recv_buf->mkey_in);
 	free_recv_pages(&qp->recv_buf);
 }
 
@@ -1445,18 +1454,29 @@ static int mlx5vf_alloc_qp_recv_resources(struct mlx5_core_dev *mdev,
 	if (err < 0)
 		return err;
 
-	err = register_dma_recv_pages(mdev, recv_buf);
-	if (err)
+	recv_buf->mkey_in = alloc_mkey_in(npages, pdn);
+	if (!recv_buf->mkey_in) {
+		err = -ENOMEM;
 		goto end;
+	}
+
+	err = register_dma_pages(mdev, npages, recv_buf->page_list,
+				 recv_buf->mkey_in);
+	if (err)
+		goto err_register_dma;
 
-	err = _create_mkey(mdev, pdn, NULL, recv_buf, &recv_buf->mkey);
+	err = create_mkey(mdev, npages, NULL, recv_buf->mkey_in,
+			  &recv_buf->mkey);
 	if (err)
 		goto err_create_mkey;
 
 	return 0;
 
 err_create_mkey:
-	unregister_dma_recv_pages(mdev, recv_buf);
+	unregister_dma_pages(mdev, npages, recv_buf->mkey_in);
+err_register_dma:
+	kvfree(recv_buf->mkey_in);
+	recv_buf->mkey_in = NULL;
 end:
 	free_recv_pages(recv_buf);
 	return err;
diff --git a/drivers/vfio/pci/mlx5/cmd.h b/drivers/vfio/pci/mlx5/cmd.h
index 7d4a833b6900..25dd6ff54591 100644
--- a/drivers/vfio/pci/mlx5/cmd.h
+++ b/drivers/vfio/pci/mlx5/cmd.h
@@ -58,8 +58,8 @@ struct mlx5_vhca_data_buffer {
 	u64 length;
 	u32 npages;
 	u32 mkey;
+	u32 *mkey_in;
 	enum dma_data_direction dma_dir;
-	u8 dmaed:1;
 	u8 stop_copy_chunk_num;
 	struct list_head buf_elm;
 	struct mlx5_vf_migration_file *migf;
@@ -133,8 +133,8 @@ struct mlx5_vhca_cq {
 struct mlx5_vhca_recv_buf {
 	u32 npages;
 	struct page **page_list;
-	dma_addr_t *dma_addrs;
 	u32 next_rq_offset;
+	u32 *mkey_in;
 	u32 mkey;
 };
 
-- 
2.46.2

[PATCH 17/18] vfio/mlx5: Explicitly store page list

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

As a preparation to removal scatter-gather table and unifying
receive and send list, explicitly store page list.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/vfio/pci/mlx5/cmd.c | 29 ++++++++++++-----------------
 drivers/vfio/pci/mlx5/cmd.h |  1 +
 2 files changed, 13 insertions(+), 17 deletions(-)

diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c
index 1832a6c1f35d..34ae3e299a9e 100644
--- a/drivers/vfio/pci/mlx5/cmd.c
+++ b/drivers/vfio/pci/mlx5/cmd.c
@@ -422,6 +422,7 @@ void mlx5vf_free_data_buffer(struct mlx5_vhca_data_buffer *buf)
 	for_each_sgtable_page(&buf->table.sgt, &sg_iter, 0)
 		__free_page(sg_page_iter_page(&sg_iter));
 	sg_free_append_table(&buf->table);
+	kvfree(buf->page_list);
 	kfree(buf);
 }
 
@@ -434,39 +435,33 @@ static int mlx5vf_add_migration_pages(struct mlx5_vhca_data_buffer *buf,
 	unsigned int to_fill;
 	int ret;
 
-	to_fill = min_t(unsigned int, npages, PAGE_SIZE / sizeof(*page_list));
-	page_list = kvzalloc(to_fill * sizeof(*page_list), GFP_KERNEL_ACCOUNT);
+	to_fill = min_t(unsigned int, npages, PAGE_SIZE / sizeof(*buf->page_list));
+	page_list = kvzalloc(to_fill * sizeof(*buf->page_list), GFP_KERNEL_ACCOUNT);
 	if (!page_list)
 		return -ENOMEM;
 
+	buf->page_list = page_list;
+
 	do {
 		filled = alloc_pages_bulk_array(GFP_KERNEL_ACCOUNT, to_fill,
-						page_list);
-		if (!filled) {
-			ret = -ENOMEM;
-			goto err;
-		}
+				buf->page_list + buf->npages);
+		if (!filled)
+			return -ENOMEM;
+
 		to_alloc -= filled;
 		ret = sg_alloc_append_table_from_pages(
-			&buf->table, page_list, filled, 0,
+			&buf->table, buf->page_list + buf->npages, filled, 0,
 			filled << PAGE_SHIFT, UINT_MAX, SG_MAX_SINGLE_ALLOC,
 			GFP_KERNEL_ACCOUNT);
 
 		if (ret)
-			goto err;
+			return ret;
 		buf->npages += filled;
-		/* clean input for another bulk allocation */
-		memset(page_list, 0, filled * sizeof(*page_list));
 		to_fill = min_t(unsigned int, to_alloc,
-				PAGE_SIZE / sizeof(*page_list));
+				PAGE_SIZE / sizeof(*buf->page_list));
 	} while (to_alloc > 0);
 
-	kvfree(page_list);
 	return 0;
-
-err:
-	kvfree(page_list);
-	return ret;
 }
 
 struct mlx5_vhca_data_buffer *
diff --git a/drivers/vfio/pci/mlx5/cmd.h b/drivers/vfio/pci/mlx5/cmd.h
index 25dd6ff54591..5b764199db53 100644
--- a/drivers/vfio/pci/mlx5/cmd.h
+++ b/drivers/vfio/pci/mlx5/cmd.h
@@ -53,6 +53,7 @@ struct mlx5_vf_migration_header {
 };
 
 struct mlx5_vhca_data_buffer {
+	struct page **page_list;
 	struct sg_append_table table;
 	loff_t start_pos;
 	u64 length;
-- 
2.46.2

[PATCH 18/18] vfio/mlx5: Convert vfio to use DMA link API

[Leon Romanovsky]

From: Leon Romanovsky <leonro@nvidia.com>

Remove intermediate scatter-gather table as it is not needed
if DMA link API is used. This conversion reduces drastically
the memory used to manage that table.

Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
---
 drivers/vfio/pci/mlx5/cmd.c  | 211 ++++++++++++++++++-----------------
 drivers/vfio/pci/mlx5/cmd.h  |   9 +-
 drivers/vfio/pci/mlx5/main.c |  31 +----
 3 files changed, 114 insertions(+), 137 deletions(-)

diff --git a/drivers/vfio/pci/mlx5/cmd.c b/drivers/vfio/pci/mlx5/cmd.c
index 34ae3e299a9e..58c490222be7 100644
--- a/drivers/vfio/pci/mlx5/cmd.c
+++ b/drivers/vfio/pci/mlx5/cmd.c
@@ -345,25 +345,81 @@ static u32 *alloc_mkey_in(u32 npages, u32 pdn)
 	return in;
 }
 
-static int create_mkey(struct mlx5_core_dev *mdev, u32 npages,
-		       struct mlx5_vhca_data_buffer *buf, u32 *mkey_in,
+static int create_mkey(struct mlx5_core_dev *mdev, u32 npages, u32 *mkey_in,
 		       u32 *mkey)
 {
+	int inlen = MLX5_ST_SZ_BYTES(create_mkey_in) +
+		sizeof(__be64) * round_up(npages, 2);
+
+	return mlx5_core_create_mkey(mdev, mkey, mkey_in, inlen);
+}
+
+static void unregister_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
+				 u32 *mkey_in, struct dma_iova_state *state,
+				 enum dma_data_direction dir)
+{
+	dma_addr_t addr;
 	__be64 *mtt;
-	int inlen;
+	int i;
 
-	mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
-	if (buf) {
-		struct sg_dma_page_iter dma_iter;
+	WARN_ON_ONCE(dir == DMA_NONE);
 
-		for_each_sgtable_dma_page(&buf->table.sgt, &dma_iter, 0)
-			*mtt++ = cpu_to_be64(sg_page_iter_dma_address(&dma_iter));
+	if (dma_use_iova(state)) {
+		dma_iova_destroy(mdev->device, state, dir, 0);
+	} else {
+		mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in,
+					     klm_pas_mtt);
+		for (i = npages - 1; i >= 0; i--) {
+			addr = be64_to_cpu(mtt[i]);
+			dma_unmap_page(mdev->device, addr, PAGE_SIZE, dir);
+		}
 	}
+}
 
-	inlen = MLX5_ST_SZ_BYTES(create_mkey_in) +
-		sizeof(__be64) * round_up(npages, 2);
+static int register_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
+			      struct page **page_list, u32 *mkey_in,
+			      struct dma_iova_state *state,
+			      enum dma_data_direction dir)
+{
+	dma_addr_t addr;
+	size_t mapped = 0;
+	__be64 *mtt;
+	int i, err;
 
-	return mlx5_core_create_mkey(mdev, mkey, mkey_in, inlen);
+	WARN_ON_ONCE(dir == DMA_NONE);
+
+	mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
+
+	if (dma_iova_try_alloc(mdev->device, state, 0, npages * PAGE_SIZE)) {
+		addr = state->addr;
+		for (i = 0; i < npages; i++) {
+			err = dma_iova_link(mdev->device, state,
+					    page_to_phys(page_list[i]), mapped,
+					    PAGE_SIZE, dir, 0);
+			if (err)
+				break;
+			*mtt++ = cpu_to_be64(addr);
+			addr += PAGE_SIZE;
+			mapped += PAGE_SIZE;
+		}
+		err = dma_iova_sync(mdev->device, state, 0, mapped, err);
+		if (err)
+			goto error;
+	} else {
+		for (i = 0; i < npages; i++) {
+			addr = dma_map_page(mdev->device, page_list[i], 0,
+					    PAGE_SIZE, dir);
+			err = dma_mapping_error(mdev->device, addr);
+			if (err)
+				goto error;
+			*mtt++ = cpu_to_be64(addr);
+		}
+	}
+	return 0;
+
+error:
+	unregister_dma_pages(mdev, i, mkey_in, state, dir);
+	return err;
 }
 
 static int mlx5vf_dma_data_buffer(struct mlx5_vhca_data_buffer *buf)
@@ -379,50 +435,57 @@ static int mlx5vf_dma_data_buffer(struct mlx5_vhca_data_buffer *buf)
 	if (buf->mkey_in || !buf->npages)
 		return -EINVAL;
 
-	ret = dma_map_sgtable(mdev->device, &buf->table.sgt, buf->dma_dir, 0);
-	if (ret)
-		return ret;
-
 	buf->mkey_in = alloc_mkey_in(buf->npages, buf->migf->pdn);
-	if (!buf->mkey_in) {
-		ret = -ENOMEM;
-		goto err;
-	}
+	if (!buf->mkey_in)
+		return -ENOMEM;
+
+	ret = register_dma_pages(mdev, buf->npages, buf->page_list,
+				 buf->mkey_in, &buf->state, buf->dma_dir);
+	if (ret)
+		goto err_register_dma;
 
-	ret = create_mkey(mdev, buf->npages, buf, buf->mkey_in, &buf->mkey);
+	ret = create_mkey(mdev, buf->npages, buf->mkey_in, &buf->mkey);
 	if (ret)
 		goto err_create_mkey;
 
 	return 0;
 
 err_create_mkey:
+	unregister_dma_pages(mdev, buf->npages, buf->mkey_in, &buf->state,
+			     buf->dma_dir);
+err_register_dma:
 	kvfree(buf->mkey_in);
 	buf->mkey_in = NULL;
-err:
-	dma_unmap_sgtable(mdev->device, &buf->table.sgt, buf->dma_dir, 0);
 	return ret;
 }
 
+static void free_page_list(u32 npages, struct page **page_list)
+{
+	int i;
+
+	/* Undo alloc_pages_bulk_array() */
+	for (i = npages - 1; i >= 0; i--)
+		__free_page(page_list[i]);
+
+	kvfree(page_list);
+}
+
 void mlx5vf_free_data_buffer(struct mlx5_vhca_data_buffer *buf)
 {
-	struct mlx5_vf_migration_file *migf = buf->migf;
-	struct sg_page_iter sg_iter;
+	struct mlx5vf_pci_core_device *mvdev = buf->migf->mvdev;
+	struct mlx5_core_dev *mdev = mvdev->mdev;
 
-	lockdep_assert_held(&migf->mvdev->state_mutex);
-	WARN_ON(migf->mvdev->mdev_detach);
+	lockdep_assert_held(&mvdev->state_mutex);
+	WARN_ON(mvdev->mdev_detach);
 
 	if (buf->mkey_in) {
-		mlx5_core_destroy_mkey(migf->mvdev->mdev, buf->mkey);
+		mlx5_core_destroy_mkey(mdev, buf->mkey);
+		unregister_dma_pages(mdev, buf->npages, buf->mkey_in,
+				     &buf->state, buf->dma_dir);
 		kvfree(buf->mkey_in);
-		dma_unmap_sgtable(migf->mvdev->mdev->device, &buf->table.sgt,
-				  buf->dma_dir, 0);
 	}
 
-	/* Undo alloc_pages_bulk_array() */
-	for_each_sgtable_page(&buf->table.sgt, &sg_iter, 0)
-		__free_page(sg_page_iter_page(&sg_iter));
-	sg_free_append_table(&buf->table);
-	kvfree(buf->page_list);
+	free_page_list(buf->npages, buf->page_list);
 	kfree(buf);
 }
 
@@ -433,7 +496,6 @@ static int mlx5vf_add_migration_pages(struct mlx5_vhca_data_buffer *buf,
 	struct page **page_list;
 	unsigned long filled;
 	unsigned int to_fill;
-	int ret;
 
 	to_fill = min_t(unsigned int, npages, PAGE_SIZE / sizeof(*buf->page_list));
 	page_list = kvzalloc(to_fill * sizeof(*buf->page_list), GFP_KERNEL_ACCOUNT);
@@ -443,22 +505,13 @@ static int mlx5vf_add_migration_pages(struct mlx5_vhca_data_buffer *buf,
 	buf->page_list = page_list;
 
 	do {
-		filled = alloc_pages_bulk_array(GFP_KERNEL_ACCOUNT, to_fill,
-				buf->page_list + buf->npages);
+		filled = alloc_pages_bulk_array(GFP_KERNEL_ACCOUNT, to_alloc,
+						buf->page_list + buf->npages);
 		if (!filled)
 			return -ENOMEM;
 
 		to_alloc -= filled;
-		ret = sg_alloc_append_table_from_pages(
-			&buf->table, buf->page_list + buf->npages, filled, 0,
-			filled << PAGE_SHIFT, UINT_MAX, SG_MAX_SINGLE_ALLOC,
-			GFP_KERNEL_ACCOUNT);
-
-		if (ret)
-			return ret;
 		buf->npages += filled;
-		to_fill = min_t(unsigned int, to_alloc,
-				PAGE_SIZE / sizeof(*buf->page_list));
 	} while (to_alloc > 0);
 
 	return 0;
@@ -1340,17 +1393,6 @@ static void mlx5vf_destroy_qp(struct mlx5_core_dev *mdev,
 	kfree(qp);
 }
 
-static void free_recv_pages(struct mlx5_vhca_recv_buf *recv_buf)
-{
-	int i;
-
-	/* Undo alloc_pages_bulk_array() */
-	for (i = 0; i < recv_buf->npages; i++)
-		__free_page(recv_buf->page_list[i]);
-
-	kvfree(recv_buf->page_list);
-}
-
 static int alloc_recv_pages(struct mlx5_vhca_recv_buf *recv_buf,
 			    unsigned int npages)
 {
@@ -1386,45 +1428,6 @@ static int alloc_recv_pages(struct mlx5_vhca_recv_buf *recv_buf,
 	kvfree(recv_buf->page_list);
 	return -ENOMEM;
 }
-static void unregister_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
-				 u32 *mkey_in)
-{
-	dma_addr_t addr;
-	__be64 *mtt;
-	int i;
-
-	mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
-	for (i = npages - 1; i >= 0; i--) {
-		addr = be64_to_cpu(mtt[i]);
-		dma_unmap_single(mdev->device, addr, PAGE_SIZE,
-				DMA_FROM_DEVICE);
-	}
-}
-
-static int register_dma_pages(struct mlx5_core_dev *mdev, u32 npages,
-			      struct page **page_list, u32 *mkey_in)
-{
-	dma_addr_t addr;
-	__be64 *mtt;
-	int i;
-
-	mtt = (__be64 *)MLX5_ADDR_OF(create_mkey_in, mkey_in, klm_pas_mtt);
-
-	for (i = 0; i < npages; i++) {
-		addr = dma_map_page(mdev->device, page_list[i], 0, PAGE_SIZE,
-				    DMA_FROM_DEVICE);
-		if (dma_mapping_error(mdev->device, addr))
-			goto error;
-
-		*mtt++ = cpu_to_be64(addr);
-	}
-
-	return 0;
-
-error:
-	unregister_dma_pages(mdev, i, mkey_in);
-	return -ENOMEM;
-}
 
 static void mlx5vf_free_qp_recv_resources(struct mlx5_core_dev *mdev,
 					  struct mlx5_vhca_qp *qp)
@@ -1432,9 +1435,10 @@ static void mlx5vf_free_qp_recv_resources(struct mlx5_core_dev *mdev,
 	struct mlx5_vhca_recv_buf *recv_buf = &qp->recv_buf;
 
 	mlx5_core_destroy_mkey(mdev, recv_buf->mkey);
-	unregister_dma_pages(mdev, recv_buf->npages, recv_buf->mkey_in);
+	unregister_dma_pages(mdev, recv_buf->npages, recv_buf->mkey_in,
+			     &recv_buf->state, DMA_FROM_DEVICE);
 	kvfree(recv_buf->mkey_in);
-	free_recv_pages(&qp->recv_buf);
+	free_page_list(recv_buf->npages, recv_buf->page_list);
 }
 
 static int mlx5vf_alloc_qp_recv_resources(struct mlx5_core_dev *mdev,
@@ -1456,24 +1460,25 @@ static int mlx5vf_alloc_qp_recv_resources(struct mlx5_core_dev *mdev,
 	}
 
 	err = register_dma_pages(mdev, npages, recv_buf->page_list,
-				 recv_buf->mkey_in);
+				 recv_buf->mkey_in, &recv_buf->state,
+				 DMA_FROM_DEVICE);
 	if (err)
 		goto err_register_dma;
 
-	err = create_mkey(mdev, npages, NULL, recv_buf->mkey_in,
-			  &recv_buf->mkey);
+	err = create_mkey(mdev, npages, recv_buf->mkey_in, &recv_buf->mkey);
 	if (err)
 		goto err_create_mkey;
 
 	return 0;
 
 err_create_mkey:
-	unregister_dma_pages(mdev, npages, recv_buf->mkey_in);
+	unregister_dma_pages(mdev, npages, recv_buf->mkey_in, &recv_buf->state,
+			     DMA_FROM_DEVICE);
 err_register_dma:
 	kvfree(recv_buf->mkey_in);
 	recv_buf->mkey_in = NULL;
 end:
-	free_recv_pages(recv_buf);
+	free_page_list(npages, recv_buf->page_list);
 	return err;
 }
 
diff --git a/drivers/vfio/pci/mlx5/cmd.h b/drivers/vfio/pci/mlx5/cmd.h
index 5b764199db53..f9c7268272e7 100644
--- a/drivers/vfio/pci/mlx5/cmd.h
+++ b/drivers/vfio/pci/mlx5/cmd.h
@@ -54,20 +54,16 @@ struct mlx5_vf_migration_header {
 
 struct mlx5_vhca_data_buffer {
 	struct page **page_list;
-	struct sg_append_table table;
+	struct dma_iova_state state;
+	enum dma_data_direction dma_dir;
 	loff_t start_pos;
 	u64 length;
 	u32 npages;
 	u32 mkey;
 	u32 *mkey_in;
-	enum dma_data_direction dma_dir;
 	u8 stop_copy_chunk_num;
 	struct list_head buf_elm;
 	struct mlx5_vf_migration_file *migf;
-	/* Optimize mlx5vf_get_migration_page() for sequential access */
-	struct scatterlist *last_offset_sg;
-	unsigned int sg_last_entry;
-	unsigned long last_offset;
 };
 
 struct mlx5vf_async_data {
@@ -134,6 +130,7 @@ struct mlx5_vhca_cq {
 struct mlx5_vhca_recv_buf {
 	u32 npages;
 	struct page **page_list;
+	struct dma_iova_state state;
 	u32 next_rq_offset;
 	u32 *mkey_in;
 	u32 mkey;
diff --git a/drivers/vfio/pci/mlx5/main.c b/drivers/vfio/pci/mlx5/main.c
index a1dbee3be1e0..cac99e6b047d 100644
--- a/drivers/vfio/pci/mlx5/main.c
+++ b/drivers/vfio/pci/mlx5/main.c
@@ -34,35 +34,10 @@ static struct mlx5vf_pci_core_device *mlx5vf_drvdata(struct pci_dev *pdev)
 			    core_device);
 }
 
-struct page *
-mlx5vf_get_migration_page(struct mlx5_vhca_data_buffer *buf,
-			  unsigned long offset)
+struct page *mlx5vf_get_migration_page(struct mlx5_vhca_data_buffer *buf,
+				       unsigned long offset)
 {
-	unsigned long cur_offset = 0;
-	struct scatterlist *sg;
-	unsigned int i;
-
-	/* All accesses are sequential */
-	if (offset < buf->last_offset || !buf->last_offset_sg) {
-		buf->last_offset = 0;
-		buf->last_offset_sg = buf->table.sgt.sgl;
-		buf->sg_last_entry = 0;
-	}
-
-	cur_offset = buf->last_offset;
-
-	for_each_sg(buf->last_offset_sg, sg,
-			buf->table.sgt.orig_nents - buf->sg_last_entry, i) {
-		if (offset < sg->length + cur_offset) {
-			buf->last_offset_sg = sg;
-			buf->sg_last_entry += i;
-			buf->last_offset = cur_offset;
-			return nth_page(sg_page(sg),
-					(offset - cur_offset) / PAGE_SIZE);
-		}
-		cur_offset += sg->length;
-	}
-	return NULL;
+	return buf->page_list[offset / PAGE_SIZE];
 }
 
 static void mlx5vf_disable_fd(struct mlx5_vf_migration_file *migf)
-- 
2.46.2

Re: [PATCH 05/18] dma: Provide an interface to allow allocate IOVA

[Baolu Lu]

On 2024/10/27 22:21, Leon Romanovsky wrote:
> From: Leon Romanovsky<leonro@nvidia.com>
> 
> The existing .map_page() callback provides both allocating of IOVA
> and linking DMA pages. That combination works great for most of the
> callers who use it in control paths, but is less effective in fast
> paths where there may be multiple calls to map_page().
> 
> These advanced callers already manage their data in some sort of
> database and can perform IOVA allocation in advance, leaving range
> linkage operation to be in fast path.
> 
> Provide an interface to allocate/deallocate IOVA and next patch
> link/unlink DMA ranges to that specific IOVA.
> 
> The API is exported from dma-iommu as it is the only implementation
> supported, the namespace is clearly different from iommu_* functions
> which are not allowed to be used. This code layout allows us to save
> function call per API call used in datapath as well as a lot of boilerplate
> code.
> 
> Signed-off-by: Leon Romanovsky<leonro@nvidia.com>
> ---
>   drivers/iommu/dma-iommu.c   | 79 +++++++++++++++++++++++++++++++++++++
>   include/linux/dma-mapping.h | 15 +++++++
>   2 files changed, 94 insertions(+)
> 
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index c422e36c0d66..0644152c5aad 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -1745,6 +1745,85 @@ size_t iommu_dma_max_mapping_size(struct device *dev)
>   	return SIZE_MAX;
>   }
>   
> +static bool iommu_dma_iova_alloc(struct device *dev,
> +		struct dma_iova_state *state, phys_addr_t phys, size_t size)
> +{
> +	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> +	struct iommu_dma_cookie *cookie = domain->iova_cookie;
> +	struct iova_domain *iovad = &cookie->iovad;
> +	size_t iova_off = iova_offset(iovad, phys);
> +	dma_addr_t addr;
> +
> +	if (WARN_ON_ONCE(!size))
> +		return false;
> +	if (WARN_ON_ONCE(size & DMA_IOVA_USE_SWIOTLB))
> +		return false;
> +
> +	addr = iommu_dma_alloc_iova(domain,
> +			iova_align(iovad, size + iova_off),
> +			dma_get_mask(dev), dev);
> +	if (!addr)
> +		return false;
> +
> +	state->addr = addr + iova_off;
> +	state->__size = size;
> +	return true;
> +}
> +
> +/**
> + * dma_iova_try_alloc - Try to allocate an IOVA space
> + * @dev: Device to allocate the IOVA space for
> + * @state: IOVA state
> + * @phys: physical address
I'm curious to know why a physical address is necessary for IOVA space
allocation. Could you please elaborate?

> + * @size: IOVA size
> + *
> + * Check if @dev supports the IOVA-based DMA API, and if yes allocate IOVA space
> + * for the given base address and size.
> + *
> + * Note: @phys is only used to calculate the IOVA alignment. Callers that always
> + * do PAGE_SIZE aligned transfers can safely pass 0 here.
> + *
> + * Returns %true if the IOVA-based DMA API can be used and IOVA space has been
> + * allocated, or %false if the regular DMA API should be used.
> + */
> +bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state,
> +		phys_addr_t phys, size_t size)
> +{
> +	memset(state, 0, sizeof(*state));
> +	if (!use_dma_iommu(dev))
> +		return false;
> +	if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&
> +	    iommu_deferred_attach(dev, iommu_get_domain_for_dev(dev)))
> +		return false;
> +	return iommu_dma_iova_alloc(dev, state, phys, size);
> +}
> +EXPORT_SYMBOL_GPL(dma_iova_try_alloc);

Thanks,
baolu

Re: [PATCH 07/18] dma-mapping: Implement link/unlink ranges API

[Baolu Lu]

On 2024/10/27 22:21, Leon Romanovsky wrote:
> +/**
> + * dma_iova_sync - Sync IOTLB
> + * @dev: DMA device
> + * @state: IOVA state
> + * @offset: offset into the IOVA state to sync
> + * @size: size of the buffer
> + * @ret: return value from the last IOVA operation
> + *
> + * Sync IOTLB for the given IOVA state. This function should be called on
> + * the IOVA-contigous range created by one ore more dma_iova_link() calls
> + * to sync the IOTLB.
> + */
> +int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
> +		size_t offset, size_t size, int ret)
> +{
> +	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> +	struct iommu_dma_cookie *cookie = domain->iova_cookie;
> +	struct iova_domain *iovad = &cookie->iovad;
> +	dma_addr_t addr = state->addr + offset;
> +	size_t iova_start_pad = iova_offset(iovad, addr);
> +
> +	addr -= iova_start_pad;
> +	size = iova_align(iovad, size + iova_start_pad);
> +
> +	if (!ret)
> +		ret = iommu_sync_map(domain, addr, size);
> +	if (ret)
> +		iommu_unmap(domain, addr, size);

It appears strange that mapping is not done in this helper, but
unmapping is added in the failure path. Perhaps I overlooked anything?
To my understanding, it should like below:

	return iommu_sync_map(domain, addr, size);

In the drivers that make use of this interface should do something like
below:

	ret = dma_iova_sync(...);
	if (ret)
		dma_iova_destroy(...)

> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(dma_iova_sync);

Thanks,
baolu

Re: [PATCH 05/18] dma: Provide an interface to allow allocate IOVA

[Srinivasulu Thanneeru]

On Sun, Oct 27, 2024 at 10:23 PM Leon Romanovsky <leon@kernel.org> wrote:
>
> From: Leon Romanovsky <leonro@nvidia.com>
>
> The existing .map_page() callback provides both allocating of IOVA
> and linking DMA pages. That combination works great for most of the
> callers who use it in control paths, but is less effective in fast
> paths where there may be multiple calls to map_page().

Can you please share perf stats with this patch in fast path, if available?

> These advanced callers already manage their data in some sort of
> database and can perform IOVA allocation in advance, leaving range
> linkage operation to be in fast path.
>
> Provide an interface to allocate/deallocate IOVA and next patch
> link/unlink DMA ranges to that specific IOVA.
>
> The API is exported from dma-iommu as it is the only implementation
> supported, the namespace is clearly different from iommu_* functions
> which are not allowed to be used. This code layout allows us to save
> function call per API call used in datapath as well as a lot of boilerplate
> code.
>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
> ---
>  drivers/iommu/dma-iommu.c   | 79 +++++++++++++++++++++++++++++++++++++
>  include/linux/dma-mapping.h | 15 +++++++
>  2 files changed, 94 insertions(+)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index c422e36c0d66..0644152c5aad 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -1745,6 +1745,85 @@ size_t iommu_dma_max_mapping_size(struct device *dev)
>         return SIZE_MAX;
>  }
>
> +static bool iommu_dma_iova_alloc(struct device *dev,
> +               struct dma_iova_state *state, phys_addr_t phys, size_t size)
> +{
> +       struct iommu_domain *domain = iommu_get_dma_domain(dev);
> +       struct iommu_dma_cookie *cookie = domain->iova_cookie;
> +       struct iova_domain *iovad = &cookie->iovad;
> +       size_t iova_off = iova_offset(iovad, phys);
> +       dma_addr_t addr;
> +
> +       if (WARN_ON_ONCE(!size))
> +               return false;
> +       if (WARN_ON_ONCE(size & DMA_IOVA_USE_SWIOTLB))
> +               return false;
> +
> +       addr = iommu_dma_alloc_iova(domain,
> +                       iova_align(iovad, size + iova_off),
> +                       dma_get_mask(dev), dev);
> +       if (!addr)
> +               return false;
> +
> +       state->addr = addr + iova_off;
> +       state->__size = size;
> +       return true;
> +}
> +
> +/**
> + * dma_iova_try_alloc - Try to allocate an IOVA space
> + * @dev: Device to allocate the IOVA space for
> + * @state: IOVA state
> + * @phys: physical address
> + * @size: IOVA size
> + *
> + * Check if @dev supports the IOVA-based DMA API, and if yes allocate IOVA space
> + * for the given base address and size.
> + *
> + * Note: @phys is only used to calculate the IOVA alignment. Callers that always
> + * do PAGE_SIZE aligned transfers can safely pass 0 here.
> + *
> + * Returns %true if the IOVA-based DMA API can be used and IOVA space has been
> + * allocated, or %false if the regular DMA API should be used.
> + */
> +bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state,
> +               phys_addr_t phys, size_t size)
> +{
> +       memset(state, 0, sizeof(*state));
> +       if (!use_dma_iommu(dev))
> +               return false;
> +       if (static_branch_unlikely(&iommu_deferred_attach_enabled) &&
> +           iommu_deferred_attach(dev, iommu_get_domain_for_dev(dev)))
> +               return false;
> +       return iommu_dma_iova_alloc(dev, state, phys, size);
> +}
> +EXPORT_SYMBOL_GPL(dma_iova_try_alloc);
> +
> +/**
> + * dma_iova_free - Free an IOVA space
> + * @dev: Device to free the IOVA space for
> + * @state: IOVA state
> + *
> + * Undoes a successful dma_try_iova_alloc().
> + *
> + * Note that all dma_iova_link() calls need to be undone first.  For callers
> + * that never call dma_iova_unlink(), dma_iova_destroy() can be used instead
> + * which unlinks all ranges and frees the IOVA space in a single efficient
> + * operation.
> + */
> +void dma_iova_free(struct device *dev, struct dma_iova_state *state)
> +{
> +       struct iommu_domain *domain = iommu_get_dma_domain(dev);
> +       struct iommu_dma_cookie *cookie = domain->iova_cookie;
> +       struct iova_domain *iovad = &cookie->iovad;
> +       size_t iova_start_pad = iova_offset(iovad, state->addr);
> +       size_t size = dma_iova_size(state);
> +
> +       iommu_dma_free_iova(cookie, state->addr - iova_start_pad,
> +                       iova_align(iovad, size + iova_start_pad), NULL);
> +}
> +EXPORT_SYMBOL_GPL(dma_iova_free);
> +
>  void iommu_setup_dma_ops(struct device *dev)
>  {
>         struct iommu_domain *domain = iommu_get_domain_for_dev(dev);
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 6075e0708deb..817f11bce7bc 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -11,6 +11,7 @@
>  #include <linux/scatterlist.h>
>  #include <linux/bug.h>
>  #include <linux/mem_encrypt.h>
> +#include <linux/iommu.h>
>
>  /**
>   * List of possible attributes associated with a DMA mapping. The semantics
> @@ -77,6 +78,7 @@
>  #define DMA_BIT_MASK(n)        (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
>
>  struct dma_iova_state {
> +       dma_addr_t addr;
>         size_t __size;
>  };
>
> @@ -307,11 +309,24 @@ static inline bool dma_use_iova(struct dma_iova_state *state)
>  {
>         return state->__size != 0;
>  }
> +
> +bool dma_iova_try_alloc(struct device *dev, struct dma_iova_state *state,
> +               phys_addr_t phys, size_t size);
> +void dma_iova_free(struct device *dev, struct dma_iova_state *state);
>  #else /* CONFIG_IOMMU_DMA */
>  static inline bool dma_use_iova(struct dma_iova_state *state)
>  {
>         return false;
>  }
> +static inline bool dma_iova_try_alloc(struct device *dev,
> +               struct dma_iova_state *state, phys_addr_t phys, size_t size)
> +{
> +       return false;
> +}
> +static inline void dma_iova_free(struct device *dev,
> +               struct dma_iova_state *state)
> +{
> +}
>  #endif /* CONFIG_IOMMU_DMA */
>
>  #if defined(CONFIG_HAS_DMA) && defined(CONFIG_DMA_NEED_SYNC)
> --
> 2.46.2
>
>

Re: [PATCH 07/18] dma-mapping: Implement link/unlink ranges API

[Leon Romanovsky]

On Mon, Oct 28, 2024 at 10:00:25AM +0800, Baolu Lu wrote:
> On 2024/10/27 22:21, Leon Romanovsky wrote:
> > +/**
> > + * dma_iova_sync - Sync IOTLB
> > + * @dev: DMA device
> > + * @state: IOVA state
> > + * @offset: offset into the IOVA state to sync
> > + * @size: size of the buffer
> > + * @ret: return value from the last IOVA operation
> > + *
> > + * Sync IOTLB for the given IOVA state. This function should be called on
> > + * the IOVA-contigous range created by one ore more dma_iova_link() calls
> > + * to sync the IOTLB.
> > + */
> > +int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
> > +		size_t offset, size_t size, int ret)
> > +{
> > +	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> > +	struct iommu_dma_cookie *cookie = domain->iova_cookie;
> > +	struct iova_domain *iovad = &cookie->iovad;
> > +	dma_addr_t addr = state->addr + offset;
> > +	size_t iova_start_pad = iova_offset(iovad, addr);
> > +
> > +	addr -= iova_start_pad;
> > +	size = iova_align(iovad, size + iova_start_pad);
> > +
> > +	if (!ret)
> > +		ret = iommu_sync_map(domain, addr, size);
> > +	if (ret)
> > +		iommu_unmap(domain, addr, size);
> 
> It appears strange that mapping is not done in this helper, but
> unmapping is added in the failure path. Perhaps I overlooked anything?

Like iommu_sync_map() is performed on whole continuous range, the iommu_unmap()
should be done on the same range. So, technically you can unmap only part of
the range which called to dma_iova_link() and failed, but you will need
to make sure that iommu_sync_map() is still called for "successful" part of
iommu_map().

In that case, you will need to undo everything anyway and it means that
you will call to iommu_unmap() on the successful part of the range
anyway.

dma_iova_sync() is single operation for the whole range and
iommu_unmap() too, so they are bound together.

> To my understanding, it should like below:
> 
> 	return iommu_sync_map(domain, addr, size);
> 
> In the drivers that make use of this interface should do something like
> below:
> 
> 	ret = dma_iova_sync(...);
> 	if (ret)
> 		dma_iova_destroy(...)

It is actually what is happening in the code, but in less direct way due
to unwinding of the code.

As an simple example, see VFIO patch https://lore.kernel.org/all/0a517ddff099c14fac1ceb0e75f2f50ed183d09c.1730037276.git.leon@kernel.org/
where failed in dma_iova_sync() will trigger call to unregister_dma_pages() and that will call to dma_iova_destroy().

> 
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(dma_iova_sync);
> 
> Thanks,
> baolu
> 

Re: [PATCH 05/18] dma: Provide an interface to allow allocate IOVA

[Leon Romanovsky]

On Mon, Oct 28, 2024 at 09:24:08AM +0800, Baolu Lu wrote:
> On 2024/10/27 22:21, Leon Romanovsky wrote:
> > From: Leon Romanovsky<leonro@nvidia.com>
> > 
> > The existing .map_page() callback provides both allocating of IOVA
> > and linking DMA pages. That combination works great for most of the
> > callers who use it in control paths, but is less effective in fast
> > paths where there may be multiple calls to map_page().
> > 
> > These advanced callers already manage their data in some sort of
> > database and can perform IOVA allocation in advance, leaving range
> > linkage operation to be in fast path.
> > 
> > Provide an interface to allocate/deallocate IOVA and next patch
> > link/unlink DMA ranges to that specific IOVA.
> > 
> > The API is exported from dma-iommu as it is the only implementation
> > supported, the namespace is clearly different from iommu_* functions
> > which are not allowed to be used. This code layout allows us to save
> > function call per API call used in datapath as well as a lot of boilerplate
> > code.
> > 
> > Signed-off-by: Leon Romanovsky<leonro@nvidia.com>
> > ---
> >   drivers/iommu/dma-iommu.c   | 79 +++++++++++++++++++++++++++++++++++++
> >   include/linux/dma-mapping.h | 15 +++++++
> >   2 files changed, 94 insertions(+)
> > 
> > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> > index c422e36c0d66..0644152c5aad 100644
> > --- a/drivers/iommu/dma-iommu.c
> > +++ b/drivers/iommu/dma-iommu.c
> > @@ -1745,6 +1745,85 @@ size_t iommu_dma_max_mapping_size(struct device *dev)
> >   	return SIZE_MAX;
> >   }
> > +static bool iommu_dma_iova_alloc(struct device *dev,
> > +		struct dma_iova_state *state, phys_addr_t phys, size_t size)
> > +{
> > +	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> > +	struct iommu_dma_cookie *cookie = domain->iova_cookie;
> > +	struct iova_domain *iovad = &cookie->iovad;
> > +	size_t iova_off = iova_offset(iovad, phys);
> > +	dma_addr_t addr;
> > +
> > +	if (WARN_ON_ONCE(!size))
> > +		return false;
> > +	if (WARN_ON_ONCE(size & DMA_IOVA_USE_SWIOTLB))
> > +		return false;
> > +
> > +	addr = iommu_dma_alloc_iova(domain,
> > +			iova_align(iovad, size + iova_off),
> > +			dma_get_mask(dev), dev);
> > +	if (!addr)
> > +		return false;
> > +
> > +	state->addr = addr + iova_off;
> > +	state->__size = size;
> > +	return true;
> > +}
> > +
> > +/**
> > + * dma_iova_try_alloc - Try to allocate an IOVA space
> > + * @dev: Device to allocate the IOVA space for
> > + * @state: IOVA state
> > + * @phys: physical address
> I'm curious to know why a physical address is necessary for IOVA space
> allocation. Could you please elaborate?

The proposed API is not only splitted to allow batching of DMA
operations without need of scatter-gather, but also allowed to
users without "struct *page" to use it. 

In IOMMU and DMA layers all operations are performed on physical
addresses and the API "request" to provide "struct *page" in
dma_map_sg/dma_map_page is not truly needed.

In this specific case, the physical address is used to calculate
IOVA offset, see "size_t iova_off = iova_offset(iovad, phys);" line,
which is needed for NVMe PCI/block layer, as they can have first
address to be unaligned and IOVA allocation will need an offset to
properly calculate size.

HMM and VFIO operate on page granularity and in simple case
they don't need alignment. In more advance scenarios, they will
benefit from this offset anyway as it will cause to reduce of IOVA
space.

Thanks

Re: [PATCH 05/18] dma: Provide an interface to allow allocate IOVA

[Leon Romanovsky]

On Mon, Oct 28, 2024 at 09:54:49AM +0530, Srinivasulu Thanneeru wrote:
> On Sun, Oct 27, 2024 at 10:23 PM Leon Romanovsky <leon@kernel.org> wrote:
> >
> > From: Leon Romanovsky <leonro@nvidia.com>
> >
> > The existing .map_page() callback provides both allocating of IOVA
> > and linking DMA pages. That combination works great for most of the
> > callers who use it in control paths, but is less effective in fast
> > paths where there may be multiple calls to map_page().
> 
> Can you please share perf stats with this patch in fast path, if available?

I don't have this data for HMM and VFIO as they have other benefits from this
series except performance. For NVMe, I don't have the data yet, but it will
come https://lore.kernel.org/all/cover.1730037261.git.leon@kernel.org/,
as it is the main performant user of this API.

This is the main reason why NVMe series is marked as RFC yet.

Thanks

Re: [PATCH 01/18] PCI/P2PDMA: refactor the p2pdma mapping helpers

[Logan Gunthorpe]

On 2024-10-27 08:21, Leon Romanovsky wrote:
> From: Christoph Hellwig <hch@lst.de>
> 
> The current scheme with a single helper to determine the P2P status
> and map a scatterlist segment force users to always use the map_sg
> helper to DMA map, which we're trying to get away from because they
> are very cache inefficient.
> 
> Refactor the code so that there is a single helper that checks the P2P
> state for a page, including the result that it is not a P2P page to
> simplify the callers, and a second one to perform the address translation
> for a bus mapped P2P transfer that does not depend on the scatterlist
> structure.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>

Looks good to me. Thanks!

Reviewed-by: Logan Gunthorpe <logang@deltatee.com>

Re: [PATCH 02/18] dma-mapping: move the PCI P2PDMA mapping helpers to pci-p2pdma.h

[Logan Gunthorpe]

On 2024-10-27 08:21, Leon Romanovsky wrote:
> From: Christoph Hellwig <hch@lst.de>
> 
> To support the upcoming non-scatterlist mapping helpers, we need to go
> back to have them called outside of the DMA API.  Thus move them out of
> dma-map-ops.h, which is only for DMA API implementations to pci-p2pdma.h,
> which is for driver use.
> 
> Note that the core helper is still not exported as the mapping is
> expected to be done only by very highlevel subsystem code at least for
> now.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>

Also looks good. Thanks!

Reviewed-by: Logan Gunthorpe <logang@deltatee.com>

Re: [PATCH 09/18] docs: core-api: document the IOVA-based API

[Logan Gunthorpe]

I noticed a couple of typos below:

On 2024-10-27 08:21, Leon Romanovsky wrote:

> +Part Ie - IOVA-based DMA mappings
> +---------------------------------
> +
> +These APIs allow a very efficient mapping when using an IOMMU.  They are an
> +optional path that requires extra code and are only recommended for drivers
> +where DMA mapping performance, or the space usage for storing the dma addresses

The second 'dma' should be capitalized as it is in other uses.


> +    int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
> +		size_t offset, size_t size, int ret);
> +
> +Must called to sync the IOMMU page tables for IOVA-range mapped by one or
> +more calls to ``dma_iova_link()``.

"Must be called" instead of "Must called"

Thanks,

Logan

Re: [PATCH 09/18] docs: core-api: document the IOVA-based API

[Leon Romanovsky]

On Mon, Oct 28, 2024 at 12:12:34PM -0600, Logan Gunthorpe wrote:
> 
> I noticed a couple of typos below:
> 
> On 2024-10-27 08:21, Leon Romanovsky wrote:
> 
> > +Part Ie - IOVA-based DMA mappings
> > +---------------------------------
> > +
> > +These APIs allow a very efficient mapping when using an IOMMU.  They are an
> > +optional path that requires extra code and are only recommended for drivers
> > +where DMA mapping performance, or the space usage for storing the dma addresses
> 
> The second 'dma' should be capitalized as it is in other uses.
> 
> 
> > +    int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
> > +		size_t offset, size_t size, int ret);
> > +
> > +Must called to sync the IOMMU page tables for IOVA-range mapped by one or
> > +more calls to ``dma_iova_link()``.
> 
> "Must be called" instead of "Must called"

Thanks, will fix.

> 
> Thanks,
> 
> Logan

Re: [PATCH 07/18] dma-mapping: Implement link/unlink ranges API

[Leon Romanovsky]

On Mon, Oct 28, 2024 at 08:22:52AM +0200, Leon Romanovsky wrote:
> On Mon, Oct 28, 2024 at 10:00:25AM +0800, Baolu Lu wrote:
> > On 2024/10/27 22:21, Leon Romanovsky wrote:
> > > +/**
> > > + * dma_iova_sync - Sync IOTLB
> > > + * @dev: DMA device
> > > + * @state: IOVA state
> > > + * @offset: offset into the IOVA state to sync
> > > + * @size: size of the buffer
> > > + * @ret: return value from the last IOVA operation
> > > + *
> > > + * Sync IOTLB for the given IOVA state. This function should be called on
> > > + * the IOVA-contigous range created by one ore more dma_iova_link() calls
> > > + * to sync the IOTLB.
> > > + */
> > > +int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
> > > +		size_t offset, size_t size, int ret)
> > > +{
> > > +	struct iommu_domain *domain = iommu_get_dma_domain(dev);
> > > +	struct iommu_dma_cookie *cookie = domain->iova_cookie;
> > > +	struct iova_domain *iovad = &cookie->iovad;
> > > +	dma_addr_t addr = state->addr + offset;
> > > +	size_t iova_start_pad = iova_offset(iovad, addr);
> > > +
> > > +	addr -= iova_start_pad;
> > > +	size = iova_align(iovad, size + iova_start_pad);
> > > +
> > > +	if (!ret)
> > > +		ret = iommu_sync_map(domain, addr, size);
> > > +	if (ret)
> > > +		iommu_unmap(domain, addr, size);
> > 
> > It appears strange that mapping is not done in this helper, but
> > unmapping is added in the failure path. Perhaps I overlooked anything?
> 
> Like iommu_sync_map() is performed on whole continuous range, the iommu_unmap()
> should be done on the same range. So, technically you can unmap only part of
> the range which called to dma_iova_link() and failed, but you will need
> to make sure that iommu_sync_map() is still called for "successful" part of
> iommu_map().
> 
> In that case, you will need to undo everything anyway and it means that
> you will call to iommu_unmap() on the successful part of the range
> anyway.
> 
> dma_iova_sync() is single operation for the whole range and
> iommu_unmap() too, so they are bound together.
> 
> > To my understanding, it should like below:
> > 
> > 	return iommu_sync_map(domain, addr, size);
> > 
> > In the drivers that make use of this interface should do something like
> > below:
> > 
> > 	ret = dma_iova_sync(...);
> > 	if (ret)
> > 		dma_iova_destroy(...)
> 
> It is actually what is happening in the code, but in less direct way due
> to unwinding of the code.

After more thoughts on the topic, I think that it will be better to make
this dma_iova_sync() less cryptic and more direct. I will change it to be
as below in my next version:

  1972 int dma_iova_sync(struct device *dev, struct dma_iova_state *state,
  1973                 size_t offset, size_t size)
  1974 {
  1975         struct iommu_domain *domain = iommu_get_dma_domain(dev);
  1976         struct iommu_dma_cookie *cookie = domain->iova_cookie;
  1977         struct iova_domain *iovad = &cookie->iovad;
  1978         dma_addr_t addr = state->addr + offset;
  1979         size_t iova_start_pad = iova_offset(iovad, addr);
  1980
  1981         return iommu_sync_map(domain, addr - iova_start_pad,
  1982                       iova_align(iovad, size + iova_start_pad));
  1983 }
  1984 EXPORT_SYMBOL_GPL(dma_iova_sync);

Thanks

Re: [PATCH 01/18] PCI/P2PDMA: refactor the p2pdma mapping helpers

[Bjorn Helgaas]

Prefer subject capitalization in drivers/pci:

  PCI/P2PDMA: Refactor ...

On Sun, Oct 27, 2024 at 04:21:01PM +0200, Leon Romanovsky wrote:
> From: Christoph Hellwig <hch@lst.de>
> 
> The current scheme with a single helper to determine the P2P status
> and map a scatterlist segment force users to always use the map_sg
> helper to DMA map, which we're trying to get away from because they
> are very cache inefficient.
> ...

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

A couple minor nits below.

> @@ -1412,28 +1411,29 @@ int iommu_dma_map_sg(struct device *dev, struct scatterlist *sg, int nents,
>  		size_t s_length = s->length;
>  		size_t pad_len = (mask - iova_len + 1) & mask;
>  
> -		if (is_pci_p2pdma_page(sg_page(s))) {
> -			map = pci_p2pdma_map_segment(&p2pdma_state, dev, s);
> -			switch (map) {
> -			case PCI_P2PDMA_MAP_BUS_ADDR:
> -				/*
> -				 * iommu_map_sg() will skip this segment as
> -				 * it is marked as a bus address,
> -				 * __finalise_sg() will copy the dma address
> -				 * into the output segment.
> -				 */
> -				continue;
> -			case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> -				/*
> -				 * Mapping through host bridge should be
> -				 * mapped with regular IOVAs, thus we
> -				 * do nothing here and continue below.
> -				 */
> -				break;
> -			default:
> -				ret = -EREMOTEIO;
> -				goto out_restore_sg;
> -			}
> +		switch (pci_p2pdma_state(&p2pdma_state, dev, sg_page(s))) {
> +		case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> +			/*
> +			 * Mapping through host bridge should be mapped with
> +			 * regular IOVAs, thus we do nothing here and continue
> +			 * below.
> +			 */

I guess this is technically not a fall-through to the next case
because there's no executable code here, but since the comment
separates these two cases, I would find it easier to read if you
included the break here explicitly.

> +		case PCI_P2PDMA_MAP_NONE:
> +			break;

> +void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
> +		struct device *dev, struct page *page);
> +
> +/**
> + * pci_p2pdma_state - check the P2P transfer state of a page
> + * @state: 	P2P state structure

Checkpatch complains about space before tab here.

> + * pci_p2pdma_bus_addr_map - map a PCI_P2PDMA_MAP_BUS_ADDR P2P transfer
> + * @state: 	P2P state structure

And here.

> @@ -462,34 +462,32 @@ int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
>  		enum dma_data_direction dir, unsigned long attrs)
>  {
>  	struct pci_p2pdma_map_state p2pdma_state = {};
> -	enum pci_p2pdma_map_type map;
>  	struct scatterlist *sg;
>  	int i, ret;
>  
>  	for_each_sg(sgl, sg, nents, i) {
> -		if (is_pci_p2pdma_page(sg_page(sg))) {
> -			map = pci_p2pdma_map_segment(&p2pdma_state, dev, sg);
> -			switch (map) {
> -			case PCI_P2PDMA_MAP_BUS_ADDR:
> -				continue;
> -			case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> -				/*
> -				 * Any P2P mapping that traverses the PCI
> -				 * host bridge must be mapped with CPU physical
> -				 * address and not PCI bus addresses. This is
> -				 * done with dma_direct_map_page() below.
> -				 */
> -				break;
> -			default:
> -				ret = -EREMOTEIO;
> +		switch (pci_p2pdma_state(&p2pdma_state, dev, sg_page(sg))) {
> +		case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
> +			/*
> +			 * Any P2P mapping that traverses the PCI host bridge
> +			 * must be mapped with CPU physical address and not PCI
> +			 * bus addresses.
> +			 */

Same fall-through comment.

> +		case PCI_P2PDMA_MAP_NONE:
> +			sg->dma_address = dma_direct_map_page(dev, sg_page(sg),
> +					sg->offset, sg->length, dir, attrs);
> +			if (sg->dma_address == DMA_MAPPING_ERROR) {
> +				ret = -EIO;
>  				goto out_unmap;
>  			}
> -		}

Re: [PATCH 05/18] dma: Provide an interface to allow allocate IOVA

[Christoph Hellwig]

On Mon, Oct 28, 2024 at 08:37:40AM +0200, Leon Romanovsky wrote:
> In this specific case, the physical address is used to calculate
> IOVA offset, see "size_t iova_off = iova_offset(iovad, phys);" line,
> which is needed for NVMe PCI/block layer, as they can have first
> address to be unaligned and IOVA allocation will need an offset to
> properly calculate size.

And that is also very explicitly spelled out in the kerneldoc comments,
including the note that the physical address is optional if the
transfer is granule aligned (actually it says PAGE_SIZE which should
be fixed).

Any suggestions to further improve it are welcome of course.

Re: [PATCH 02/18] dma-mapping: move the PCI P2PDMA mapping helpers to pci-p2pdma.h

[Bjorn Helgaas]

On Sun, Oct 27, 2024 at 04:21:02PM +0200, Leon Romanovsky wrote:
> From: Christoph Hellwig <hch@lst.de>
> 
> To support the upcoming non-scatterlist mapping helpers, we need to go
> back to have them called outside of the DMA API.  Thus move them out of
> dma-map-ops.h, which is only for DMA API implementations to pci-p2pdma.h,
> which is for driver use.
> 
> Note that the core helper is still not exported as the mapping is
> expected to be done only by very highlevel subsystem code at least for
> now.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Signed-off-by: Leon Romanovsky <leonro@nvidia.com>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/iommu/dma-iommu.c   |  1 +
>  include/linux/dma-map-ops.h | 84 -------------------------------------
>  include/linux/pci-p2pdma.h  | 84 +++++++++++++++++++++++++++++++++++++
>  kernel/dma/direct.c         |  1 +
>  4 files changed, 86 insertions(+), 84 deletions(-)
> 
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 6e50023c8112..c422e36c0d66 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -26,6 +26,7 @@
>  #include <linux/mutex.h>
>  #include <linux/of_iommu.h>
>  #include <linux/pci.h>
> +#include <linux/pci-p2pdma.h>
>  #include <linux/scatterlist.h>
>  #include <linux/spinlock.h>
>  #include <linux/swiotlb.h>
> diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
> index 49edcbda19d1..6ee626e50708 100644
> --- a/include/linux/dma-map-ops.h
> +++ b/include/linux/dma-map-ops.h
> @@ -435,88 +435,4 @@ static inline void debug_dma_dump_mappings(struct device *dev)
>  
>  extern const struct dma_map_ops dma_dummy_ops;
>  
> -enum pci_p2pdma_map_type {
> -	/*
> -	 * PCI_P2PDMA_MAP_UNKNOWN: Used internally for indicating the mapping
> -	 * type hasn't been calculated yet. Functions that return this enum
> -	 * never return this value.
> -	 */
> -	PCI_P2PDMA_MAP_UNKNOWN = 0,
> -
> -	/*
> -	 * Not a PCI P2PDMA transfer.
> -	 */
> -	PCI_P2PDMA_MAP_NONE,
> -
> -	/*
> -	 * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will
> -	 * traverse the host bridge and the host bridge is not in the
> -	 * allowlist. DMA Mapping routines should return an error when
> -	 * this is returned.
> -	 */
> -	PCI_P2PDMA_MAP_NOT_SUPPORTED,
> -
> -	/*
> -	 * PCI_P2PDMA_BUS_ADDR: Indicates that two devices can talk to
> -	 * each other directly through a PCI switch and the transaction will
> -	 * not traverse the host bridge. Such a mapping should program
> -	 * the DMA engine with PCI bus addresses.
> -	 */
> -	PCI_P2PDMA_MAP_BUS_ADDR,
> -
> -	/*
> -	 * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: Indicates two devices can talk
> -	 * to each other, but the transaction traverses a host bridge on the
> -	 * allowlist. In this case, a normal mapping either with CPU physical
> -	 * addresses (in the case of dma-direct) or IOVA addresses (in the
> -	 * case of IOMMUs) should be used to program the DMA engine.
> -	 */
> -	PCI_P2PDMA_MAP_THRU_HOST_BRIDGE,
> -};
> -
> -struct pci_p2pdma_map_state {
> -	struct dev_pagemap *pgmap;
> -	enum pci_p2pdma_map_type map;
> -	u64 bus_off;
> -};
> -
> -/* helper for pci_p2pdma_state(), do not use directly */
> -void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
> -		struct device *dev, struct page *page);
> -
> -/**
> - * pci_p2pdma_state - check the P2P transfer state of a page
> - * @state: 	P2P state structure
> - * @dev:	device to transfer to/from
> - * @page:	page to map
> - *
> - * Check if @page is a PCI P2PDMA page, and if yes of what kind.  Returns the
> - * map type, and updates @state with all information needed for a P2P transfer.
> - */
> -static inline enum pci_p2pdma_map_type
> -pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev,
> -		struct page *page)
> -{
> -	if (IS_ENABLED(CONFIG_PCI_P2PDMA) && is_pci_p2pdma_page(page)) {
> -		if (state->pgmap != page->pgmap)
> -			__pci_p2pdma_update_state(state, dev, page);
> -		return state->map;
> -	}
> -	return PCI_P2PDMA_MAP_NONE;
> -}
> -
> -/**
> - * pci_p2pdma_bus_addr_map - map a PCI_P2PDMA_MAP_BUS_ADDR P2P transfer
> - * @state: 	P2P state structure
> - * @paddr:	physical address to map
> - *
> - * Map a physically contigous PCI_P2PDMA_MAP_BUS_ADDR transfer.
> - */
> -static inline dma_addr_t
> -pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr)
> -{
> -	WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR);
> -	return paddr + state->bus_off;
> -}
> -
>  #endif /* _LINUX_DMA_MAP_OPS_H */
> diff --git a/include/linux/pci-p2pdma.h b/include/linux/pci-p2pdma.h
> index 2c07aa6b7665..66b71f60a811 100644
> --- a/include/linux/pci-p2pdma.h
> +++ b/include/linux/pci-p2pdma.h
> @@ -104,4 +104,88 @@ static inline struct pci_dev *pci_p2pmem_find(struct device *client)
>  	return pci_p2pmem_find_many(&client, 1);
>  }
>  
> +enum pci_p2pdma_map_type {
> +	/*
> +	 * PCI_P2PDMA_MAP_UNKNOWN: Used internally for indicating the mapping
> +	 * type hasn't been calculated yet. Functions that return this enum
> +	 * never return this value.
> +	 */
> +	PCI_P2PDMA_MAP_UNKNOWN = 0,
> +
> +	/*
> +	 * Not a PCI P2PDMA transfer.
> +	 */
> +	PCI_P2PDMA_MAP_NONE,
> +
> +	/*
> +	 * PCI_P2PDMA_MAP_NOT_SUPPORTED: Indicates the transaction will
> +	 * traverse the host bridge and the host bridge is not in the
> +	 * allowlist. DMA Mapping routines should return an error when
> +	 * this is returned.
> +	 */
> +	PCI_P2PDMA_MAP_NOT_SUPPORTED,
> +
> +	/*
> +	 * PCI_P2PDMA_BUS_ADDR: Indicates that two devices can talk to
> +	 * each other directly through a PCI switch and the transaction will
> +	 * not traverse the host bridge. Such a mapping should program
> +	 * the DMA engine with PCI bus addresses.
> +	 */
> +	PCI_P2PDMA_MAP_BUS_ADDR,
> +
> +	/*
> +	 * PCI_P2PDMA_MAP_THRU_HOST_BRIDGE: Indicates two devices can talk
> +	 * to each other, but the transaction traverses a host bridge on the
> +	 * allowlist. In this case, a normal mapping either with CPU physical
> +	 * addresses (in the case of dma-direct) or IOVA addresses (in the
> +	 * case of IOMMUs) should be used to program the DMA engine.
> +	 */
> +	PCI_P2PDMA_MAP_THRU_HOST_BRIDGE,
> +};
> +
> +struct pci_p2pdma_map_state {
> +	struct dev_pagemap *pgmap;
> +	enum pci_p2pdma_map_type map;
> +	u64 bus_off;
> +};
> +
> +/* helper for pci_p2pdma_state(), do not use directly */
> +void __pci_p2pdma_update_state(struct pci_p2pdma_map_state *state,
> +		struct device *dev, struct page *page);
> +
> +/**
> + * pci_p2pdma_state - check the P2P transfer state of a page
> + * @state: 	P2P state structure
> + * @dev:	device to transfer to/from
> + * @page:	page to map
> + *
> + * Check if @page is a PCI P2PDMA page, and if yes of what kind.  Returns the
> + * map type, and updates @state with all information needed for a P2P transfer.
> + */
> +static inline enum pci_p2pdma_map_type
> +pci_p2pdma_state(struct pci_p2pdma_map_state *state, struct device *dev,
> +		struct page *page)
> +{
> +	if (IS_ENABLED(CONFIG_PCI_P2PDMA) && is_pci_p2pdma_page(page)) {
> +		if (state->pgmap != page->pgmap)
> +			__pci_p2pdma_update_state(state, dev, page);
> +		return state->map;
> +	}
> +	return PCI_P2PDMA_MAP_NONE;
> +}
> +
> +/**
> + * pci_p2pdma_bus_addr_map - map a PCI_P2PDMA_MAP_BUS_ADDR P2P transfer
> + * @state: 	P2P state structure
> + * @paddr:	physical address to map
> + *
> + * Map a physically contigous PCI_P2PDMA_MAP_BUS_ADDR transfer.
> + */
> +static inline dma_addr_t
> +pci_p2pdma_bus_addr_map(struct pci_p2pdma_map_state *state, phys_addr_t paddr)
> +{
> +	WARN_ON_ONCE(state->map != PCI_P2PDMA_MAP_BUS_ADDR);
> +	return paddr + state->bus_off;
> +}
> +
>  #endif /* _LINUX_PCI_P2P_H */
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index a793400161c2..47e124561fff 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -13,6 +13,7 @@
>  #include <linux/vmalloc.h>
>  #include <linux/set_memory.h>
>  #include <linux/slab.h>
> +#include <linux/pci-p2pdma.h>
>  #include "direct.h"
>  
>  /*
> -- 
> 2.46.2
> 

Re: [PATCH 01/18] PCI/P2PDMA: refactor the p2pdma mapping helpers

[Leon Romanovsky]

On Mon, Oct 28, 2024 at 03:59:02PM -0500, Bjorn Helgaas wrote:
> Prefer subject capitalization in drivers/pci:
> 
>   PCI/P2PDMA: Refactor ...
> 
> On Sun, Oct 27, 2024 at 04:21:01PM +0200, Leon Romanovsky wrote:
> > From: Christoph Hellwig <hch@lst.de>
> > 
> > The current scheme with a single helper to determine the P2P status
> > and map a scatterlist segment force users to always use the map_sg
> > helper to DMA map, which we're trying to get away from because they
> > are very cache inefficient.
> > ...
> 
> Acked-by: Bjorn Helgaas <bhelgaas@google.com>
> 
> A couple minor nits below.

I'll fix, thanks