[PATCH rdma-next v3 03/17] RDMA/core: Introduce generic buffer descriptor infrastructure for umem

[Jiri Pirko <jiri@resnulli.us>]

From: Jiri Pirko <jiri@nvidia.com>

Introduce a per-attribute UVERBS_ATTR_UMEM model so each uverbs
command's umem set is explicit in its UAPI definition. Add
driver-facing wrapper helpers that pin a umem on demand from an
attribute or a VA addr; the driver owns the returned umem and
releases it from its destroy/error paths.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
---
v2->v3:
- pushed out desc processing to ib_umem_get_desc()
- replaced UVERBS_ATTR_BUFFERS array with per-attribute UVERBS_ATTR_UMEM
- struct ib_uverbs_buffer_desc: dropped .index, moved .type first,
  bumped reserved to __u32 reserved[2]
- added canonical ib_umem_get() + two inline wrappers
  (_attr, _attr_or_va)
- dropped ib_umem_list_* family + ib_umem_release_non_listed()
---
 drivers/infiniband/core/umem.c          | 105 ++++++++++++++++++++++++
 include/rdma/ib_umem.h                  |  55 +++++++++++++
 include/rdma/uverbs_ioctl.h             |  12 +++
 include/uapi/rdma/ib_user_ioctl_verbs.h |  23 ++++++
 4 files changed, 195 insertions(+)

diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
index 6e0906f0f5c4..d9073b1012bc 100644
--- a/drivers/infiniband/core/umem.c
+++ b/drivers/infiniband/core/umem.c
@@ -272,6 +272,111 @@ static struct ib_umem *__ib_umem_get_va(struct ib_device *device,
 	return ret ? ERR_PTR(ret) : umem;
 }
 
+static struct ib_umem *
+ib_umem_get_desc(struct ib_device *device,
+		 const struct ib_uverbs_buffer_desc *desc, int access)
+{
+	struct ib_umem_dmabuf *umem_dmabuf;
+
+	if (desc->reserved[0] || desc->reserved[1])
+		return ERR_PTR(-EINVAL);
+
+	switch (desc->type) {
+	case IB_UVERBS_BUFFER_TYPE_DMABUF:
+		umem_dmabuf = ib_umem_dmabuf_get_pinned(device, desc->addr,
+							desc->length, desc->fd,
+							access);
+		if (IS_ERR(umem_dmabuf))
+			return ERR_CAST(umem_dmabuf);
+		return &umem_dmabuf->umem;
+	case IB_UVERBS_BUFFER_TYPE_VA:
+		return __ib_umem_get_va(device, desc->addr, desc->length,
+					access);
+	default:
+		return ERR_PTR(-EINVAL);
+	}
+}
+
+/**
+ * ib_umem_get - Canonical on-demand umem getter.
+ * @device:        IB device.
+ * @udata:         uverbs udata bundle (may be NULL).
+ * @attr_id:       per-command UMEM attribute id; consulted if @udata is set.
+ * @legacy_filler: optional command-specific legacy attr filler.
+ *                 invoked if @udata is set.
+ * @va_fallback:   if true, build a VA-typed desc with @addr.
+ * @addr:          user VA, used if @va_fallback is true.
+ * @size:          driver-required minimum length.
+ * @access:        IB access flags forwarded to ib_umem_get_desc().
+ *
+ * Return: valid umem on success, ERR_PTR(...) on error, NULL
+ * if no source produced a buffer (only possible when @va_fallback is false).
+ */
+struct ib_umem *ib_umem_get(struct ib_device *device, struct ib_udata *udata,
+			    u16 attr_id,
+			    ib_umem_buf_desc_filler_t legacy_filler,
+			    bool va_fallback, u64 addr, size_t size, int access)
+{
+	struct uverbs_attr_bundle *attrs = NULL;
+	struct ib_uverbs_buffer_desc desc = {};
+	bool have_desc = false;
+	struct ib_umem *umem;
+	int ret;
+
+	if (udata)
+		attrs = container_of(udata, struct uverbs_attr_bundle,
+				     driver_udata);
+
+	if (attrs) {
+		ret = uverbs_copy_from(&desc, attrs, attr_id);
+		if (!ret)
+			have_desc = true;
+		else if (ret != -ENOENT)
+			return ERR_PTR(ret);
+	}
+
+	if (attrs && legacy_filler) {
+		struct ib_uverbs_buffer_desc legacy_desc = {};
+
+		ret = legacy_filler(attrs, &legacy_desc);
+		if (!ret) {
+			if (have_desc) {
+				ibdev_err(device,
+					  "UMEM attr (id=%u) and legacy attrs are mutually exclusive\n",
+					  attr_id);
+				return ERR_PTR(-EINVAL);
+			}
+			memcpy(&desc, &legacy_desc, sizeof(desc));
+			have_desc = true;
+		} else if (ret != -ENODATA) {
+			return ERR_PTR(ret);
+		}
+	}
+
+	if (have_desc)
+		goto have_desc;
+
+	if (!va_fallback)
+		return NULL;
+
+	desc = (struct ib_uverbs_buffer_desc){
+		.type	= IB_UVERBS_BUFFER_TYPE_VA,
+		.addr	= addr,
+		.length	= size,
+	};
+
+have_desc:
+	umem = ib_umem_get_desc(device, &desc, access);
+	if (IS_ERR(umem))
+		return umem;
+	if (umem->length < size) {
+		ib_umem_release(umem);
+		return ERR_PTR(-EINVAL);
+	}
+	return umem;
+}
+EXPORT_SYMBOL(ib_umem_get);
+
 /**
  * ib_umem_get_va - Pin and DMA map userspace memory.
  *
diff --git a/include/rdma/ib_umem.h b/include/rdma/ib_umem.h
index 25e90766892e..4897c7599fa3 100644
--- a/include/rdma/ib_umem.h
+++ b/include/rdma/ib_umem.h
@@ -73,10 +73,44 @@ static inline size_t ib_umem_num_pages(struct ib_umem *umem)
 {
 	return ib_umem_num_dma_blocks(umem, PAGE_SIZE);
 }
+
+struct ib_udata;
+struct ib_uverbs_buffer_desc;
+struct uverbs_attr_bundle;
+
+/*
+ * Per-command legacy buffer-desc filler.
+ * Returns 0 on success (desc filled), -ENODATA if no legacy attrs apply,
+ * negative errno on validation failure.
+ */
+typedef int (*ib_umem_buf_desc_filler_t)(struct uverbs_attr_bundle *attrs,
+					 struct ib_uverbs_buffer_desc *desc);
+
 #ifdef CONFIG_INFINIBAND_USER_MEM
 
+struct ib_umem *ib_umem_get(struct ib_device *device, struct ib_udata *udata,
+			    u16 attr_id,
+			    ib_umem_buf_desc_filler_t legacy_filler,
+			    bool va_fallback, u64 addr, size_t size, int access);
 struct ib_umem *ib_umem_get_va(struct ib_device *device, unsigned long addr,
 			       size_t size, int access);
+
+static inline struct ib_umem *
+ib_umem_get_attr(struct ib_device *device, struct ib_udata *udata,
+		 u16 attr_id, size_t size, int access)
+{
+	return ib_umem_get(device, udata, attr_id, NULL,
+			   false, 0, size, access);
+}
+
+static inline struct ib_umem *
+ib_umem_get_attr_or_va(struct ib_device *device, struct ib_udata *udata,
+		       u16 attr_id, u64 addr, size_t size, int access)
+{
+	return ib_umem_get(device, udata, attr_id, NULL,
+			   true, addr, size, access);
+}
+
 void ib_umem_release(struct ib_umem *umem);
 int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,
 		      size_t length);
@@ -160,12 +194,33 @@ void ib_umem_dmabuf_revoke(struct ib_umem_dmabuf *umem_dmabuf);
 
 #include <linux/err.h>
 
+static inline struct ib_umem *
+ib_umem_get(struct ib_device *device, struct ib_udata *udata, u16 attr_id,
+	    ib_umem_buf_desc_filler_t legacy_filler, bool va_fallback, u64 addr,
+	    size_t size, int access)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
 static inline struct ib_umem *ib_umem_get_va(struct ib_device *device,
 					     unsigned long addr, size_t size,
 					     int access)
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
+static inline struct ib_umem *ib_umem_get_attr(struct ib_device *device,
+					       struct ib_udata *udata,
+					       u16 attr_id, size_t size,
+					       int access)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+static inline struct ib_umem *ib_umem_get_attr_or_va(struct ib_device *device,
+						     struct ib_udata *udata,
+						     u16 attr_id, u64 addr,
+						     size_t size, int access)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
 static inline void ib_umem_release(struct ib_umem *umem) { }
 static inline int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,
 		      		    size_t length) {
diff --git a/include/rdma/uverbs_ioctl.h b/include/rdma/uverbs_ioctl.h
index e2af17da3e32..76e94ede668e 100644
--- a/include/rdma/uverbs_ioctl.h
+++ b/include/rdma/uverbs_ioctl.h
@@ -590,6 +590,18 @@ struct uapi_definition {
 			    UA_OPTIONAL,                                       \
 			    .is_udata = 1)
 
+/*
+ * Per-attribute UMEM descriptor. The payload is a single
+ * struct ib_uverbs_buffer_desc identifying a memory region backed by
+ * dma-buf or user virtual address. _access selects UA_OPTIONAL or
+ * UA_MANDATORY. Drivers obtain a umem from the attribute via the
+ * ib_umem_get_*() wrapper helpers.
+ */
+#define UVERBS_ATTR_UMEM(_attr_id, _access)                                    \
+	UVERBS_ATTR_PTR_IN(_attr_id,                                           \
+			   UVERBS_ATTR_TYPE(struct ib_uverbs_buffer_desc),     \
+			   _access)
+
 /* =================================================
  *              Parsing infrastructure
  * =================================================
diff --git a/include/uapi/rdma/ib_user_ioctl_verbs.h b/include/uapi/rdma/ib_user_ioctl_verbs.h
index 90c5cd8e7753..6dfb95d56770 100644
--- a/include/uapi/rdma/ib_user_ioctl_verbs.h
+++ b/include/uapi/rdma/ib_user_ioctl_verbs.h
@@ -273,4 +273,27 @@ struct ib_uverbs_gid_entry {
 	__u32 netdev_ifindex; /* It is 0 if there is no netdev associated with it */
 };
 
+enum ib_uverbs_buffer_type {
+	IB_UVERBS_BUFFER_TYPE_DMABUF,
+	IB_UVERBS_BUFFER_TYPE_VA,
+};
+
+/*
+ * Describes a single buffer backed by dma-buf or user virtual address.
+ * Used as the payload of a per-attribute UVERBS_ATTR_UMEM-typed attribute.
+ *
+ * @type: buffer type from enum ib_uverbs_buffer_type
+ * @fd: dma-buf file descriptor (valid for IB_UVERBS_BUFFER_TYPE_DMABUF)
+ * @reserved: must be zero
+ * @addr: offset within dma-buf, or user virtual address for VA
+ * @length: buffer length in bytes
+ */
+struct ib_uverbs_buffer_desc {
+	__u32 type;
+	__s32 fd;
+	__u32 reserved[2];
+	__aligned_u64 addr;
+	__aligned_u64 length;
+};
+
 #endif
-- 
2.53.0