xen: import new ring macros in ring.h

Sync the ring.h file with upstream Xen, to introduce the new ring macros.
They will be used by the Xen transport for 9pfs.

CC: konrad.wilk@oracle.com
CC: boris.ostrovsky@oracle.com
CC: jgross@suse.com
CC: groug@kaod.org

Signed-off-by: Stefano Stabellini <stefano@aporeto.com>
Acked-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
This commit is contained in:
Stefano Stabellini 2017-04-05 12:03:55 -07:00 committed by Juergen Gross
parent ab1570a427
commit 564f7dfde2
1 changed files with 143 additions and 0 deletions

View File

@ -283,4 +283,147 @@ struct __name##_back_ring { \
(_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r); \
} while (0)
/*
* DEFINE_XEN_FLEX_RING_AND_INTF defines two monodirectional rings and
* functions to check if there is data on the ring, and to read and
* write to them.
*
* DEFINE_XEN_FLEX_RING is similar to DEFINE_XEN_FLEX_RING_AND_INTF, but
* does not define the indexes page. As different protocols can have
* extensions to the basic format, this macro allow them to define their
* own struct.
*
* XEN_FLEX_RING_SIZE
* Convenience macro to calculate the size of one of the two rings
* from the overall order.
*
* $NAME_mask
* Function to apply the size mask to an index, to reduce the index
* within the range [0-size].
*
* $NAME_read_packet
* Function to read data from the ring. The amount of data to read is
* specified by the "size" argument.
*
* $NAME_write_packet
* Function to write data to the ring. The amount of data to write is
* specified by the "size" argument.
*
* $NAME_get_ring_ptr
* Convenience function that returns a pointer to read/write to the
* ring at the right location.
*
* $NAME_data_intf
* Indexes page, shared between frontend and backend. It also
* contains the array of grant refs.
*
* $NAME_queued
* Function to calculate how many bytes are currently on the ring,
* ready to be read. It can also be used to calculate how much free
* space is currently on the ring (XEN_FLEX_RING_SIZE() -
* $NAME_queued()).
*/
#ifndef XEN_PAGE_SHIFT
/* The PAGE_SIZE for ring protocols and hypercall interfaces is always
* 4K, regardless of the architecture, and page granularity chosen by
* operating systems.
*/
#define XEN_PAGE_SHIFT 12
#endif
#define XEN_FLEX_RING_SIZE(order) \
(1UL << ((order) + XEN_PAGE_SHIFT - 1))
#define DEFINE_XEN_FLEX_RING(name) \
static inline RING_IDX name##_mask(RING_IDX idx, RING_IDX ring_size) \
{ \
return idx & (ring_size - 1); \
} \
\
static inline unsigned char *name##_get_ring_ptr(unsigned char *buf, \
RING_IDX idx, \
RING_IDX ring_size) \
{ \
return buf + name##_mask(idx, ring_size); \
} \
\
static inline void name##_read_packet(void *opaque, \
const unsigned char *buf, \
size_t size, \
RING_IDX masked_prod, \
RING_IDX *masked_cons, \
RING_IDX ring_size) \
{ \
if (*masked_cons < masked_prod || \
size <= ring_size - *masked_cons) { \
memcpy(opaque, buf + *masked_cons, size); \
} else { \
memcpy(opaque, buf + *masked_cons, ring_size - *masked_cons); \
memcpy((unsigned char *)opaque + ring_size - *masked_cons, buf, \
size - (ring_size - *masked_cons)); \
} \
*masked_cons = name##_mask(*masked_cons + size, ring_size); \
} \
\
static inline void name##_write_packet(unsigned char *buf, \
const void *opaque, \
size_t size, \
RING_IDX *masked_prod, \
RING_IDX masked_cons, \
RING_IDX ring_size) \
{ \
if (*masked_prod < masked_cons || \
size <= ring_size - *masked_prod) { \
memcpy(buf + *masked_prod, opaque, size); \
} else { \
memcpy(buf + *masked_prod, opaque, ring_size - *masked_prod); \
memcpy(buf, (unsigned char *)opaque + (ring_size - *masked_prod), \
size - (ring_size - *masked_prod)); \
} \
*masked_prod = name##_mask(*masked_prod + size, ring_size); \
} \
\
static inline RING_IDX name##_queued(RING_IDX prod, \
RING_IDX cons, \
RING_IDX ring_size) \
{ \
RING_IDX size; \
\
if (prod == cons) \
return 0; \
\
prod = name##_mask(prod, ring_size); \
cons = name##_mask(cons, ring_size); \
\
if (prod == cons) \
return ring_size; \
\
if (prod > cons) \
size = prod - cons; \
else \
size = ring_size - (cons - prod); \
return size; \
} \
\
struct name##_data { \
unsigned char *in; /* half of the allocation */ \
unsigned char *out; /* half of the allocation */ \
}
#define DEFINE_XEN_FLEX_RING_AND_INTF(name) \
struct name##_data_intf { \
RING_IDX in_cons, in_prod; \
\
uint8_t pad1[56]; \
\
RING_IDX out_cons, out_prod; \
\
uint8_t pad2[56]; \
\
RING_IDX ring_order; \
grant_ref_t ref[]; \
}; \
DEFINE_XEN_FLEX_RING(name)
#endif /* __XEN_PUBLIC_IO_RING_H__ */