misc: mic: SCIF RMA header file and IOCTL changes

This patch updates the SCIF header file and IOCTL interface with the
changes required to support RMAs. APIs added include the ability to
pin pages and register those pages with SCIF. SCIF kernel clients can
also add references to remote registered pages and access them via the
CPU. The user space IOCTL interface has been updated to enable SCIF
registration, RDMA/CPU copies and fence APIs for RDMA synchronization.

Reviewed-by: Nikhil Rao <[e-mail]>
Reviewed-by: Ashutosh Dixit <[e-mail]>
Signed-off-by: Sudeep Dutt <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

include/linux/scif.h

···
 #define SCIF_PORT_RSVD		1088
 
 typedef struct scif_endpt *scif_epd_t;
+typedef struct scif_pinned_pages *scif_pinned_pages_t;
+
+/**
+ * struct scif_range - SCIF registered range used in kernel mode
+ * @cookie: cookie used internally by SCIF
+ * @nr_pages: number of pages of PAGE_SIZE
+ * @prot_flags: R/W protection
+ * @phys_addr: Array of bus addresses
+ * @va: Array of kernel virtual addresses backed by the pages in the phys_addr
+ *	array. The va is populated only when called on the host for a remote
+ *	SCIF connection on MIC. This is required to support the use case of DMA
+ *	between MIC and another device which is not a SCIF node e.g., an IB or
+ *	ethernet NIC.
+ */
+struct scif_range {
+	void *cookie;
+	int nr_pages;
+	int prot_flags;
+	dma_addr_t *phys_addr;
+	void __iomem **va;
+};
 
 /**
  * struct scif_pollepd - SCIF endpoint to be monitored via scif_poll
···
  * Errors:
  * EBADF, ENOTTY - epd is not a valid endpoint descriptor
  * ECONNRESET - Connection reset by peer
- * EFAULT - An invalid address was specified for a parameter
  * EINVAL - flags is invalid, or len is negative
  * ENODEV - The remote node is lost or existed, but is not currently in the
  * network since it may have crashed
···
  * EAGAIN - The destination node is returning from a low power state
  * EBADF, ENOTTY - epd is not a valid endpoint descriptor
  * ECONNRESET - Connection reset by peer
- * EFAULT - An invalid address was specified for a parameter
  * EINVAL - flags is invalid, or len is negative
  * ENODEV - The remote node is lost or existed, but is not currently in the
  * network since it may have crashed
···
  * SCIF_PROT_READ - allow read operations from the window
  * SCIF_PROT_WRITE - allow write operations to the window
  *
- * The map_flags argument can be set to SCIF_MAP_FIXED which interprets a
- * fixed offset.
- *
  * Return:
  * Upon successful completion, scif_register() returns the offset at which the
  * mapping was placed (po); otherwise in user mode SCIF_REGISTER_FAILED (that
···
  * EAGAIN - The mapping could not be performed due to lack of resources
  * EBADF, ENOTTY - epd is not a valid endpoint descriptor
  * ECONNRESET - Connection reset by peer
- * EFAULT - Addresses in the range [addr, addr + len - 1] are invalid
  * EINVAL - map_flags is invalid, or prot_flags is invalid, or SCIF_MAP_FIXED is
  * set in flags, and offset is not a multiple of the page size, or addr is not a
  * multiple of the page size, or len is not a multiple of the page size, or is
···
  * EACCESS - Attempt to write to a read-only range
  * EBADF, ENOTTY - epd is not a valid endpoint descriptor
  * ECONNRESET - Connection reset by peer
- * EFAULT - Addresses in the range [addr, addr + len - 1] are invalid
  * EINVAL - rma_flags is invalid
  * ENODEV - The remote node is lost or existed, but is not currently in the
  * network since it may have crashed
···
  * EACCESS - Attempt to write to a read-only range
  * EBADF, ENOTTY - epd is not a valid endpoint descriptor
  * ECONNRESET - Connection reset by peer
- * EFAULT - Addresses in the range [addr, addr + len - 1] are invalid
  * EINVAL - rma_flags is invalid
  * ENODEV - The remote node is lost or existed, but is not currently in the
  * network since it may have crashed
···
  * online nodes in the SCIF network including 'self'; otherwise in user mode
  * -1 is returned and errno is set to indicate the error; in kernel mode no
  * errors are returned.
- *
- * Errors:
- * EFAULT - Bad address
  */
 int scif_get_node_ids(u16 *nodes, int len, u16 *self);
+
+/**
+ * scif_pin_pages() - Pin a set of pages
+ * @addr:		Virtual address of range to pin
+ * @len:		Length of range to pin
+ * @prot_flags:		Page protection flags
+ * @map_flags:		Page classification flags
+ * @pinned_pages:	Handle to pinned pages
+ *
+ * scif_pin_pages() pins (locks in physical memory) the physical pages which
+ * back the range of virtual address pages starting at addr and continuing for
+ * len bytes. addr and len are constrained to be multiples of the page size. A
+ * successful scif_pin_pages() call returns a handle to pinned_pages which may
+ * be used in subsequent calls to scif_register_pinned_pages().
+ *
+ * The pages will remain pinned as long as there is a reference against the
+ * scif_pinned_pages_t value returned by scif_pin_pages() and until
+ * scif_unpin_pages() is called, passing the scif_pinned_pages_t value. A
+ * reference is added to a scif_pinned_pages_t value each time a window is
+ * created by calling scif_register_pinned_pages() and passing the
+ * scif_pinned_pages_t value. A reference is removed from a
+ * scif_pinned_pages_t value each time such a window is deleted.
+ *
+ * Subsequent operations which change the memory pages to which virtual
+ * addresses are mapped (such as mmap(), munmap()) have no effect on the
+ * scif_pinned_pages_t value or windows created against it.
+ *
+ * If the process will fork(), it is recommended that the registered
+ * virtual address range be marked with MADV_DONTFORK. Doing so will prevent
+ * problems due to copy-on-write semantics.
+ *
+ * The prot_flags argument is formed by OR'ing together one or more of the
+ * following values.
+ * SCIF_PROT_READ - allow read operations against the pages
+ * SCIF_PROT_WRITE - allow write operations against the pages
+ * The map_flags argument can be set as SCIF_MAP_KERNEL to interpret addr as a
+ * kernel space address. By default, addr is interpreted as a user space
+ * address.
+ *
+ * Return:
+ * Upon successful completion, scif_pin_pages() returns 0; otherwise the
+ * negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EINVAL - prot_flags is invalid, map_flags is invalid, or offset is negative
+ * ENOMEM - Not enough space
+ */
+int scif_pin_pages(void *addr, size_t len, int prot_flags, int map_flags,
+		   scif_pinned_pages_t *pinned_pages);
+
+/**
+ * scif_unpin_pages() - Unpin a set of pages
+ * @pinned_pages:	Handle to pinned pages to be unpinned
+ *
+ * scif_unpin_pages() prevents scif_register_pinned_pages() from registering new
+ * windows against pinned_pages. The physical pages represented by pinned_pages
+ * will remain pinned until all windows previously registered against
+ * pinned_pages are deleted (the window is scif_unregister()'d and all
+ * references to the window are removed (see scif_unregister()).
+ *
+ * pinned_pages must have been obtain from a previous call to scif_pin_pages().
+ * After calling scif_unpin_pages(), it is an error to pass pinned_pages to
+ * scif_register_pinned_pages().
+ *
+ * Return:
+ * Upon successful completion, scif_unpin_pages() returns 0; otherwise the
+ * negative of one of the following errors is returned.
+ *
+ * Errors:
+ * EINVAL - pinned_pages is not valid
+ */
+int scif_unpin_pages(scif_pinned_pages_t pinned_pages);
+
+/**
+ * scif_register_pinned_pages() - Mark a memory region for remote access.
+ * @epd:		endpoint descriptor
+ * @pinned_pages:	Handle to pinned pages
+ * @offset:		Registered address space offset
+ * @map_flags:		Flags which control where pages are mapped
+ *
+ * The scif_register_pinned_pages() function opens a window, a range of whole
+ * pages of the registered address space of the endpoint epd, starting at
+ * offset po. The value of po, further described below, is a function of the
+ * parameters offset and pinned_pages, and the value of map_flags. Each page of
+ * the window represents a corresponding physical memory page of the range
+ * represented by pinned_pages; the length of the window is the same as the
+ * length of range represented by pinned_pages. A successful
+ * scif_register_pinned_pages() call returns po as the return value.
+ *
+ * When SCIF_MAP_FIXED is set in the map_flags argument, po will be offset
+ * exactly, and offset is constrained to be a multiple of the page size. The
+ * mapping established by scif_register_pinned_pages() will not replace any
+ * existing registration; an error is returned if any page of the new window
+ * would intersect an existing window.
+ *
+ * When SCIF_MAP_FIXED is not set, the implementation uses offset in an
+ * implementation-defined manner to arrive at po. The po so chosen will be an
+ * area of the registered address space that the implementation deems suitable
+ * for a mapping of the required size. An offset value of 0 is interpreted as
+ * granting the implementation complete freedom in selecting po, subject to
+ * constraints described below. A non-zero value of offset is taken to be a
+ * suggestion of an offset near which the mapping should be placed. When the
+ * implementation selects a value for po, it does not replace any extant
+ * window. In all cases, po will be a multiple of the page size.
+ *
+ * The physical pages which are so represented by a window are available for
+ * access in calls to scif_get_pages(), scif_readfrom(), scif_writeto(),
+ * scif_vreadfrom(), and scif_vwriteto(). While a window is registered, the
+ * physical pages represented by the window will not be reused by the memory
+ * subsystem for any other purpose. Note that the same physical page may be
+ * represented by multiple windows.
+ *
+ * Windows created by scif_register_pinned_pages() are unregistered by
+ * scif_unregister().
+ *
+ * The map_flags argument can be set to SCIF_MAP_FIXED which interprets a
+ * fixed offset.
+ *
+ * Return:
+ * Upon successful completion, scif_register_pinned_pages() returns the offset
+ * at which the mapping was placed (po); otherwise the negative of one of the
+ * following errors is returned.
+ *
+ * Errors:
+ * EADDRINUSE - SCIF_MAP_FIXED is set in map_flags and pages in the new window
+ * would intersect an existing window
+ * EAGAIN - The mapping could not be performed due to lack of resources
+ * ECONNRESET - Connection reset by peer
+ * EINVAL - map_flags is invalid, or SCIF_MAP_FIXED is set in map_flags, and
+ * offset is not a multiple of the page size, or offset is negative
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOMEM - Not enough space
+ * ENOTCONN - The endpoint is not connected
+ */
+off_t scif_register_pinned_pages(scif_epd_t epd,
+				 scif_pinned_pages_t pinned_pages,
+				 off_t offset, int map_flags);
+
+/**
+ * scif_get_pages() - Add references to remote registered pages
+ * @epd:	endpoint descriptor
+ * @offset:	remote registered offset
+ * @len:	length of range of pages
+ * @pages:	returned scif_range structure
+ *
+ * scif_get_pages() returns the addresses of the physical pages represented by
+ * those pages of the registered address space of the peer of epd, starting at
+ * offset and continuing for len bytes. offset and len are constrained to be
+ * multiples of the page size.
+ *
+ * All of the pages in the specified range [offset, offset + len - 1] must be
+ * within a single window of the registered address space of the peer of epd.
+ *
+ * The addresses are returned as a virtually contiguous array pointed to by the
+ * phys_addr component of the scif_range structure whose address is returned in
+ * pages. The nr_pages component of scif_range is the length of the array. The
+ * prot_flags component of scif_range holds the protection flag value passed
+ * when the pages were registered.
+ *
+ * Each physical page whose address is returned by scif_get_pages() remains
+ * available and will not be released for reuse until the scif_range structure
+ * is returned in a call to scif_put_pages(). The scif_range structure returned
+ * by scif_get_pages() must be unmodified.
+ *
+ * It is an error to call scif_close() on an endpoint on which a scif_range
+ * structure of that endpoint has not been returned to scif_put_pages().
+ *
+ * Return:
+ * Upon successful completion, scif_get_pages() returns 0; otherwise the
+ * negative of one of the following errors is returned.
+ * Errors:
+ * ECONNRESET - Connection reset by peer.
+ * EINVAL - offset is not a multiple of the page size, or offset is negative, or
+ * len is not a multiple of the page size
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ * ENXIO - Offsets in the range [offset, offset + len - 1] are invalid
+ * for the registered address space of the peer epd
+ */
+int scif_get_pages(scif_epd_t epd, off_t offset, size_t len,
+		   struct scif_range **pages);
+
+/**
+ * scif_put_pages() - Remove references from remote registered pages
+ * @pages:	pages to be returned
+ *
+ * scif_put_pages() releases a scif_range structure previously obtained by
+ * calling scif_get_pages(). The physical pages represented by pages may
+ * be reused when the window which represented those pages is unregistered.
+ * Therefore, those pages must not be accessed after calling scif_put_pages().
+ *
+ * Return:
+ * Upon successful completion, scif_put_pages() returns 0; otherwise the
+ * negative of one of the following errors is returned.
+ * Errors:
+ * EINVAL - pages does not point to a valid scif_range structure, or
+ * the scif_range structure pointed to by pages was already returned
+ * ENODEV - The remote node is lost or existed, but is not currently in the
+ * network since it may have crashed
+ * ENOTCONN - The endpoint is not connected
+ */
+int scif_put_pages(struct scif_range *pages);
 
 /**
  * scif_poll() - Wait for some event on an endpoint

include/uapi/linux/scif_ioctl.h

···
 };
 
 /**
+ * struct scifioctl_reg - used for SCIF_REG IOCTL
+ * @addr:	starting virtual address
+ * @len:	length of range
+ * @offset:	offset of window
+ * @prot:	read/write protection
+ * @flags:	flags
+ * @out_offset:	offset returned
+ */
+struct scifioctl_reg {
+	__u64		addr;
+	__u64		len;
+	__s64		offset;
+	__s32		prot;
+	__s32		flags;
+	__s64		out_offset;
+};
+
+/**
+ * struct scifioctl_unreg - used for SCIF_UNREG IOCTL
+ * @offset:	start of range to unregister
+ * @len:	length of range to unregister
+ */
+struct scifioctl_unreg {
+	__s64		offset;
+	__u64		len;
+};
+
+/**
+ * struct scifioctl_copy - used for SCIF DMA copy IOCTLs
+ *
+ * @loffset:	offset in local registered address space to/from
+ *		which to copy
+ * @len:	length of range to copy
+ * @roffset:	offset in remote registered address space to/from
+ *		which to copy
+ * @addr:	user virtual address to/from which to copy
+ * @flags:	flags
+ *
+ * This structure is used for SCIF_READFROM, SCIF_WRITETO, SCIF_VREADFROM
+ * and SCIF_VREADFROM IOCTL's.
+ */
+struct scifioctl_copy {
+	__s64		loffset;
+	__u64		len;
+	__s64		roffset;
+	__u64		addr;
+	__s32		flags;
+};
+
+/**
+ * struct scifioctl_fence_mark  - used for SCIF_FENCE_MARK IOCTL
+ * @flags:	flags
+ * @mark:	fence handle which is a pointer to a __s32
+ */
+struct scifioctl_fence_mark {
+	__s32	flags;
+	__u64	mark;
+};
+
+/**
+ * struct scifioctl_fence_signal - used for SCIF_FENCE_SIGNAL IOCTL
+ * @loff:	local offset
+ * @lval:	value to write to loffset
+ * @roff:	remote offset
+ * @rval:	value to write to roffset
+ * @flags:	flags
+ */
+struct scifioctl_fence_signal {
+	__s64		loff;
+	__u64		lval;
+	__s64		roff;
+	__u64		rval;
+	__s32		flags;
+};
+
+/**
  * struct scifioctl_node_ids - used for SCIF_GET_NODEIDS IOCTL
  * @nodes:	pointer to an array of node_ids
  * @self:	ID of the current node
···
 #define SCIF_ACCEPTREG		_IOWR('s', 5, __u64)
 #define SCIF_SEND		_IOWR('s', 6, struct scifioctl_msg)
 #define SCIF_RECV		_IOWR('s', 7, struct scifioctl_msg)
+#define SCIF_REG		_IOWR('s', 8, struct scifioctl_reg)
+#define SCIF_UNREG		_IOWR('s', 9, struct scifioctl_unreg)
+#define SCIF_READFROM		_IOWR('s', 10, struct scifioctl_copy)
+#define SCIF_WRITETO		_IOWR('s', 11, struct scifioctl_copy)
+#define SCIF_VREADFROM		_IOWR('s', 12, struct scifioctl_copy)
+#define SCIF_VWRITETO		_IOWR('s', 13, struct scifioctl_copy)
 #define SCIF_GET_NODEIDS	_IOWR('s', 14, struct scifioctl_node_ids)
+#define SCIF_FENCE_MARK		_IOWR('s', 15, struct scifioctl_fence_mark)
+#define SCIF_FENCE_WAIT		_IOWR('s', 16, __s32)
+#define SCIF_FENCE_SIGNAL	_IOWR('s', 17, struct scifioctl_fence_signal)
 
 #endif /* SCIF_IOCTL_H */