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memory: introduce memory_region_find()

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Given an address space (represented by the top-level memory region),
returns the memory region that maps a given range.  Useful for implementing
DMA.

The implementation is a simplistic binary search.  Once we have a tree
representation this can be optimized.

Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Avi Kivity 2011-12-08 15:00:18 +02:00
parent 55043ba37e
commit e2177955a8
2 changed files with 101 additions and 0 deletions
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39
memory.h
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@ -148,6 +148,24 @@ struct MemoryRegionPortio {
#define PORTIO_END_OF_LIST() { }
typedef struct MemoryRegionSection MemoryRegionSection;
/**
* MemoryRegionSection: describes a fragment of a #MemoryRegion
*
* @mr: the region, or %NULL if empty
* @offset_within_region: the beginning of the section, relative to @mr's start
* @size: the size of the section; will not exceed @mr's boundaries
* @offset_within_address_space: the address of the first byte of the section
* relative to the region's address space
*/
struct MemoryRegionSection {
MemoryRegion *mr;
target_phys_addr_t offset_within_region;
uint64_t size;
target_phys_addr_t offset_within_address_space;
};
/**
* memory_region_init: Initialize a memory region
*
@ -568,6 +586,27 @@ void memory_region_set_address(MemoryRegion *mr, target_phys_addr_t addr);
void memory_region_set_alias_offset(MemoryRegion *mr,
target_phys_addr_t offset);
/**
* memory_region_find: locate a MemoryRegion in an address space
*
* Locates the first #MemoryRegion within an address space given by
* @address_space that overlaps the range given by @addr and @size.
*
* Returns a #MemoryRegionSection that describes a contiguous overlap.
* It will have the following characteristics:
* .@offset_within_address_space >= @addr
* .@offset_within_address_space + .@size <= @addr + @size
* .@size = 0 iff no overlap was found
* .@mr is non-%NULL iff an overlap was found
*
* @address_space: a top-level (i.e. parentless) region that contains
* the region to be found
* @addr: start of the area within @address_space to be searched
* @size: size of the area to be searched
*/
MemoryRegionSection memory_region_find(MemoryRegion *address_space,
target_phys_addr_t addr, uint64_t size);
/**
* memory_region_transaction_begin: Start a transaction.
*