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qemu/dma.h
Benjamin Herrenschmidt 7a0bac4da9 Add a memory barrier to DMA functions 
The emulated devices can run simultaneously with the guest, so
we need to be careful with ordering of load and stores done by
them to the guest system memory, which need to be observed in
the right order by the guest operating system.

This adds a barrier call to the basic DMA read/write ops which
is currently implemented as a smp_mb(), but could be later
improved for more fine grained control of barriers.

Additionally, a _relaxed() variant of the accessors is provided
to easily convert devices who would be performance sensitive
and negatively impacted by the change.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
2012-06-27 16:33:26 -05:00

279 lines
9.5 KiB
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/*
* DMA helper functions
*
* Copyright (c) 2009 Red Hat
*
* This work is licensed under the terms of the GNU General Public License
* (GNU GPL), version 2 or later.
*/
#ifndef DMA_H
#define DMA_H
#include <stdio.h>
#include "hw/hw.h"
#include "block.h"
#include "kvm.h"
typedef struct DMAContext DMAContext;
typedef struct ScatterGatherEntry ScatterGatherEntry;
typedef enum {
DMA_DIRECTION_TO_DEVICE = 0,
DMA_DIRECTION_FROM_DEVICE = 1,
} DMADirection;
struct QEMUSGList {
ScatterGatherEntry *sg;
int nsg;
int nalloc;
size_t size;
DMAContext *dma;
};
#if defined(TARGET_PHYS_ADDR_BITS)
/*
* When an IOMMU is present, bus addresses become distinct from
* CPU/memory physical addresses and may be a different size. Because
* the IOVA size depends more on the bus than on the platform, we more
* or less have to treat these as 64-bit always to cover all (or at
* least most) cases.
*/
typedef uint64_t dma_addr_t;
#define DMA_ADDR_BITS 64
#define DMA_ADDR_FMT "%" PRIx64
typedef int DMATranslateFunc(DMAContext *dma,
dma_addr_t addr,
target_phys_addr_t *paddr,
target_phys_addr_t *len,
DMADirection dir);
typedef void* DMAMapFunc(DMAContext *dma,
dma_addr_t addr,
dma_addr_t *len,
DMADirection dir);
typedef void DMAUnmapFunc(DMAContext *dma,
void *buffer,
dma_addr_t len,
DMADirection dir,
dma_addr_t access_len);
struct DMAContext {
DMATranslateFunc *translate;
DMAMapFunc *map;
DMAUnmapFunc *unmap;
};
static inline void dma_barrier(DMAContext *dma, DMADirection dir)
{
/*
* This is called before DMA read and write operations
* unless the _relaxed form is used and is responsible
* for providing some sane ordering of accesses vs
* concurrently running VCPUs.
*
* Users of map(), unmap() or lower level st/ld_*
* operations are responsible for providing their own
* ordering via barriers.
*
* This primitive implementation does a simple smp_mb()
* before each operation which provides pretty much full
* ordering.
*
* A smarter implementation can be devised if needed to
* use lighter barriers based on the direction of the
* transfer, the DMA context, etc...
*/
if (kvm_enabled()) {
smp_mb();
}
}
static inline bool dma_has_iommu(DMAContext *dma)
{
return !!dma;
}
/* Checks that the given range of addresses is valid for DMA. This is
* useful for certain cases, but usually you should just use
* dma_memory_{read,write}() and check for errors */
bool iommu_dma_memory_valid(DMAContext *dma, dma_addr_t addr, dma_addr_t len,
DMADirection dir);
static inline bool dma_memory_valid(DMAContext *dma,
dma_addr_t addr, dma_addr_t len,
DMADirection dir)
{
if (!dma_has_iommu(dma)) {
return true;
} else {
return iommu_dma_memory_valid(dma, addr, len, dir);
}
}
int iommu_dma_memory_rw(DMAContext *dma, dma_addr_t addr,
void *buf, dma_addr_t len, DMADirection dir);
static inline int dma_memory_rw_relaxed(DMAContext *dma, dma_addr_t addr,
void *buf, dma_addr_t len,
DMADirection dir)
{
if (!dma_has_iommu(dma)) {
/* Fast-path for no IOMMU */
cpu_physical_memory_rw(addr, buf, len,
dir == DMA_DIRECTION_FROM_DEVICE);
return 0;
} else {
return iommu_dma_memory_rw(dma, addr, buf, len, dir);
}
}
static inline int dma_memory_read_relaxed(DMAContext *dma, dma_addr_t addr,
void *buf, dma_addr_t len)
{
return dma_memory_rw_relaxed(dma, addr, buf, len, DMA_DIRECTION_TO_DEVICE);
}
static inline int dma_memory_write_relaxed(DMAContext *dma, dma_addr_t addr,
const void *buf, dma_addr_t len)
{
return dma_memory_rw_relaxed(dma, addr, (void *)buf, len,
DMA_DIRECTION_FROM_DEVICE);
}
static inline int dma_memory_rw(DMAContext *dma, dma_addr_t addr,
void *buf, dma_addr_t len,
DMADirection dir)
{
dma_barrier(dma, dir);
return dma_memory_rw_relaxed(dma, addr, buf, len, dir);
}
static inline int dma_memory_read(DMAContext *dma, dma_addr_t addr,
void *buf, dma_addr_t len)
{
return dma_memory_rw(dma, addr, buf, len, DMA_DIRECTION_TO_DEVICE);
}
static inline int dma_memory_write(DMAContext *dma, dma_addr_t addr,
const void *buf, dma_addr_t len)
{
return dma_memory_rw(dma, addr, (void *)buf, len,
DMA_DIRECTION_FROM_DEVICE);
}
int iommu_dma_memory_set(DMAContext *dma, dma_addr_t addr, uint8_t c,
dma_addr_t len);
int dma_memory_set(DMAContext *dma, dma_addr_t addr, uint8_t c, dma_addr_t len);
void *iommu_dma_memory_map(DMAContext *dma,
dma_addr_t addr, dma_addr_t *len,
DMADirection dir);
static inline void *dma_memory_map(DMAContext *dma,
dma_addr_t addr, dma_addr_t *len,
DMADirection dir)
{
if (!dma_has_iommu(dma)) {
target_phys_addr_t xlen = *len;
void *p;
p = cpu_physical_memory_map(addr, &xlen,
dir == DMA_DIRECTION_FROM_DEVICE);
*len = xlen;
return p;
} else {
return iommu_dma_memory_map(dma, addr, len, dir);
}
}
void iommu_dma_memory_unmap(DMAContext *dma,
void *buffer, dma_addr_t len,
DMADirection dir, dma_addr_t access_len);
static inline void dma_memory_unmap(DMAContext *dma,
void *buffer, dma_addr_t len,
DMADirection dir, dma_addr_t access_len)
{
if (!dma_has_iommu(dma)) {
return cpu_physical_memory_unmap(buffer, (target_phys_addr_t)len,
dir == DMA_DIRECTION_FROM_DEVICE,
access_len);
} else {
iommu_dma_memory_unmap(dma, buffer, len, dir, access_len);
}
}
#define DEFINE_LDST_DMA(_lname, _sname, _bits, _end) \
static inline uint##_bits##_t ld##_lname##_##_end##_dma(DMAContext *dma, \
dma_addr_t addr) \
{ \
uint##_bits##_t val; \
dma_memory_read(dma, addr, &val, (_bits) / 8); \
return _end##_bits##_to_cpu(val); \
} \
static inline void st##_sname##_##_end##_dma(DMAContext *dma, \
dma_addr_t addr, \
uint##_bits##_t val) \
{ \
val = cpu_to_##_end##_bits(val); \
dma_memory_write(dma, addr, &val, (_bits) / 8); \
}
static inline uint8_t ldub_dma(DMAContext *dma, dma_addr_t addr)
{
uint8_t val;
dma_memory_read(dma, addr, &val, 1);
return val;
}
static inline void stb_dma(DMAContext *dma, dma_addr_t addr, uint8_t val)
{
dma_memory_write(dma, addr, &val, 1);
}
DEFINE_LDST_DMA(uw, w, 16, le);
DEFINE_LDST_DMA(l, l, 32, le);
DEFINE_LDST_DMA(q, q, 64, le);
DEFINE_LDST_DMA(uw, w, 16, be);
DEFINE_LDST_DMA(l, l, 32, be);
DEFINE_LDST_DMA(q, q, 64, be);
#undef DEFINE_LDST_DMA
void dma_context_init(DMAContext *dma, DMATranslateFunc translate,
DMAMapFunc map, DMAUnmapFunc unmap);
struct ScatterGatherEntry {
dma_addr_t base;
dma_addr_t len;
};
void qemu_sglist_init(QEMUSGList *qsg, int alloc_hint, DMAContext *dma);
void qemu_sglist_add(QEMUSGList *qsg, dma_addr_t base, dma_addr_t len);
void qemu_sglist_destroy(QEMUSGList *qsg);
#endif
typedef BlockDriverAIOCB *DMAIOFunc(BlockDriverState *bs, int64_t sector_num,
QEMUIOVector *iov, int nb_sectors,
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *dma_bdrv_io(BlockDriverState *bs,
QEMUSGList *sg, uint64_t sector_num,
DMAIOFunc *io_func, BlockDriverCompletionFunc *cb,
void *opaque, DMADirection dir);
BlockDriverAIOCB *dma_bdrv_read(BlockDriverState *bs,
QEMUSGList *sg, uint64_t sector,
BlockDriverCompletionFunc *cb, void *opaque);
BlockDriverAIOCB *dma_bdrv_write(BlockDriverState *bs,
QEMUSGList *sg, uint64_t sector,
BlockDriverCompletionFunc *cb, void *opaque);
uint64_t dma_buf_read(uint8_t *ptr, int32_t len, QEMUSGList *sg);
uint64_t dma_buf_write(uint8_t *ptr, int32_t len, QEMUSGList *sg);
void dma_acct_start(BlockDriverState *bs, BlockAcctCookie *cookie,
QEMUSGList *sg, enum BlockAcctType type);
#endif
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