diff options
Diffstat (limited to 'include/xen/interface/io/ring.h')
| -rw-r--r-- | include/xen/interface/io/ring.h | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h index 21f4fbd55e48..c79456855539 100644 --- a/include/xen/interface/io/ring.h +++ b/include/xen/interface/io/ring.h @@ -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__ */ |