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Add target memory mapping API (Avi Kivity)

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Devices accessing large amounts of memory (as with DMA) will wish to obtain
a pointer to guest memory rather than access it indirectly via
cpu_physical_memory_rw().  Add a new API to convert target addresses to
host pointers.

In case the target address does not correspond to RAM, a bounce buffer is
allocated.  To prevent the guest from causing the host to allocate unbounded
amounts of bounce buffer, this memory is limited (currently to one page).

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6394 c046a42c-6fe2-441c-8c8c-71466251a162
This commit is contained in:
aliguori 2009-01-22 16:59:11 +00:00
parent d268de04f2
commit 6d16c2f88f
2 changed files with 108 additions and 0 deletions
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6
cpu-all.h
View File

@ -923,6 +923,12 @@ static inline void cpu_physical_memory_write(target_phys_addr_t addr,
{
cpu_physical_memory_rw(addr, (uint8_t *)buf, len, 1);
}
void *cpu_physical_memory_map(target_phys_addr_t addr,
target_phys_addr_t *plen,
int is_write);
void cpu_physical_memory_unmap(void *buffer, target_phys_addr_t len,
int is_write, target_phys_addr_t access_len);
uint32_t ldub_phys(target_phys_addr_t addr);
uint32_t lduw_phys(target_phys_addr_t addr);
uint32_t ldl_phys(target_phys_addr_t addr);

102
exec.c
View File

@ -3045,6 +3045,108 @@ void cpu_physical_memory_write_rom(target_phys_addr_t addr,
}
}
typedef struct {
void *buffer;
target_phys_addr_t addr;
target_phys_addr_t len;
} BounceBuffer;
static BounceBuffer bounce;
/* Map a physical memory region into a host virtual address.
* May map a subset of the requested range, given by and returned in *plen.
* May return NULL if resources needed to perform the mapping are exhausted.
* Use only for reads OR writes - not for read-modify-write operations.
*/
void *cpu_physical_memory_map(target_phys_addr_t addr,
target_phys_addr_t *plen,
int is_write)
{
target_phys_addr_t len = *plen;
target_phys_addr_t done = 0;
int l;
uint8_t *ret = NULL;
uint8_t *ptr;
target_phys_addr_t page;
unsigned long pd;
PhysPageDesc *p;
unsigned long addr1;
while (len > 0) {
page = addr & TARGET_PAGE_MASK;
l = (page + TARGET_PAGE_SIZE) - addr;
if (l > len)
l = len;
p = phys_page_find(page >> TARGET_PAGE_BITS);
if (!p) {
pd = IO_MEM_UNASSIGNED;
} else {
pd = p->phys_offset;
}
if ((pd & ~TARGET_PAGE_MASK) != IO_MEM_RAM) {
if (done || bounce.buffer) {
break;
}
bounce.buffer = qemu_memalign(TARGET_PAGE_SIZE, TARGET_PAGE_SIZE);
bounce.addr = addr;
bounce.len = l;
if (!is_write) {
cpu_physical_memory_rw(addr, bounce.buffer, l, 0);
}
ptr = bounce.buffer;
} else {
addr1 = (pd & TARGET_PAGE_MASK) + (addr & ~TARGET_PAGE_MASK);
ptr = phys_ram_base + addr1;
}
if (!done) {
ret = ptr;
} else if (ret + done != ptr) {
break;
}
len -= l;
addr += l;
done += l;
}
*plen = done;
return ret;
}
/* Unmaps a memory region previously mapped by cpu_physical_memory_map().
* Will also mark the memory as dirty if is_write == 1. access_len gives
* the amount of memory that was actually read or written by the caller.
*/
void cpu_physical_memory_unmap(void *buffer, target_phys_addr_t len,
int is_write, target_phys_addr_t access_len)
{
if (buffer != bounce.buffer) {
if (is_write) {
unsigned long addr1 = (uint8_t *)buffer - phys_ram_base;
while (access_len) {
unsigned l;
l = TARGET_PAGE_SIZE;
if (l > access_len)
l = access_len;
if (!cpu_physical_memory_is_dirty(addr1)) {
/* invalidate code */
tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
/* set dirty bit */
phys_ram_dirty[addr1 >> TARGET_PAGE_BITS] |=
(0xff & ~CODE_DIRTY_FLAG);
}
addr1 += l;
access_len -= l;
}
}
return;
}
if (is_write) {
cpu_physical_memory_write(bounce.addr, bounce.buffer, access_len);
}
qemu_free(bounce.buffer);
bounce.buffer = NULL;
}
/* warning: addr must be aligned */
uint32_t ldl_phys(target_phys_addr_t addr)