提交 e2177955 编写于 作者: A Avi Kivity

memory: introduce memory_region_find()

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: NAvi Kivity <avi@redhat.com>
上级 55043ba3
......@@ -515,6 +515,20 @@ static AddressSpace address_space_io = {
.ops = &address_space_ops_io,
};
static AddressSpace *memory_region_to_address_space(MemoryRegion *mr)
{
while (mr->parent) {
mr = mr->parent;
}
if (mr == address_space_memory.root) {
return &address_space_memory;
}
if (mr == address_space_io.root) {
return &address_space_io;
}
abort();
}
/* Render a memory region into the global view. Ranges in @view obscure
* ranges in @mr.
*/
......@@ -1386,6 +1400,54 @@ void memory_region_set_alias_offset(MemoryRegion *mr, target_phys_addr_t offset)
memory_region_update_topology(mr);
}
static int cmp_flatrange_addr(const void *addr_, const void *fr_)
{
const AddrRange *addr = addr_;
const FlatRange *fr = fr_;
if (int128_le(addrrange_end(*addr), fr->addr.start)) {
return -1;
} else if (int128_ge(addr->start, addrrange_end(fr->addr))) {
return 1;
}
return 0;
}
static FlatRange *address_space_lookup(AddressSpace *as, AddrRange addr)
{
return bsearch(&addr, as->current_map.ranges, as->current_map.nr,
sizeof(FlatRange), cmp_flatrange_addr);
}
MemoryRegionSection memory_region_find(MemoryRegion *address_space,
target_phys_addr_t addr, uint64_t size)
{
AddressSpace *as = memory_region_to_address_space(address_space);
AddrRange range = addrrange_make(int128_make64(addr),
int128_make64(size));
FlatRange *fr = address_space_lookup(as, range);
MemoryRegionSection ret = { .mr = NULL, .size = 0 };
if (!fr) {
return ret;
}
while (fr > as->current_map.ranges
&& addrrange_intersects(fr[-1].addr, range)) {
--fr;
}
ret.mr = fr->mr;
range = addrrange_intersection(range, fr->addr);
ret.offset_within_region = fr->offset_in_region;
ret.offset_within_region += int128_get64(int128_sub(range.start,
fr->addr.start));
ret.size = int128_get64(range.size);
ret.offset_within_address_space = int128_get64(range.start);
return ret;
}
void set_system_memory_map(MemoryRegion *mr)
{
address_space_memory.root = mr;
......
......@@ -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.
*
......
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