qemu/include/sysemu/dma.h

/*
 * DMA helper functions
 *
 * Copyright (c) 2009, 2020 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 "exec/memory.h"
#include "exec/address-spaces.h"
#include "block/block.h"
#include "block/accounting.h"

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;
    DeviceState *dev;
    AddressSpace *as;
};

#ifndef CONFIG_USER_ONLY

/*
 * 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

static inline void dma_barrier(AddressSpace *as, 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...
     */
    smp_mb();
}

/* 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 */
static inline bool dma_memory_valid(AddressSpace *as,
                                    dma_addr_t addr, dma_addr_t len,
                                    DMADirection dir)
{
    return address_space_access_valid(as, addr, len,
                                      dir == DMA_DIRECTION_FROM_DEVICE,
                                      MEMTXATTRS_UNSPECIFIED);
}

static inline MemTxResult dma_memory_rw_relaxed(AddressSpace *as,
                                                dma_addr_t addr,
                                                void *buf, dma_addr_t len,
                                                DMADirection dir)
{
    return address_space_rw(as, addr, MEMTXATTRS_UNSPECIFIED,
                            buf, len, dir == DMA_DIRECTION_FROM_DEVICE);
}

static inline int dma_memory_read_relaxed(AddressSpace *as, dma_addr_t addr,
                                          void *buf, dma_addr_t len)
{
    return dma_memory_rw_relaxed(as, addr, buf, len, DMA_DIRECTION_TO_DEVICE);
}

static inline int dma_memory_write_relaxed(AddressSpace *as, dma_addr_t addr,
                                           const void *buf, dma_addr_t len)
{
    return dma_memory_rw_relaxed(as, addr, (void *)buf, len,
                                 DMA_DIRECTION_FROM_DEVICE);
}

/**
 * dma_memory_rw: Read from or write to an address space from DMA controller.
 *
 * Return a MemTxResult indicating whether the operation succeeded
 * or failed (eg unassigned memory, device rejected the transaction,
 * IOMMU fault).
 *
 * @as: #AddressSpace to be accessed
 * @addr: address within that address space
 * @buf: buffer with the data transferred
 * @len: the number of bytes to read or write
 * @dir: indicates the transfer direction
 */
static inline MemTxResult dma_memory_rw(AddressSpace *as, dma_addr_t addr,
                                        void *buf, dma_addr_t len,
                                        DMADirection dir)
{
    dma_barrier(as, dir);

    return dma_memory_rw_relaxed(as, addr, buf, len, dir);
}

static inline int dma_memory_read(AddressSpace *as, dma_addr_t addr,
                                  void *buf, dma_addr_t len)
{
    return dma_memory_rw(as, addr, buf, len, DMA_DIRECTION_TO_DEVICE);
}

static inline int dma_memory_write(AddressSpace *as, dma_addr_t addr,
                                   const void *buf, dma_addr_t len)
{
    return dma_memory_rw(as, addr, (void *)buf, len,
                         DMA_DIRECTION_FROM_DEVICE);
}

/**
 * dma_memory_set: Fill memory with a constant byte from DMA controller.
 *
 * Return a MemTxResult indicating whether the operation succeeded
 * or failed (eg unassigned memory, device rejected the transaction,
 * IOMMU fault).
 *
 * @as: #AddressSpace to be accessed
 * @addr: address within that address space
 * @c: constant byte to fill the memory
 * @len: the number of bytes to fill with the constant byte
 */
MemTxResult dma_memory_set(AddressSpace *as, dma_addr_t addr,
                           uint8_t c, dma_addr_t len);

/**
 * address_space_map: 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 and set *@plen to zero(0), if resources needed to perform
 * the mapping are exhausted.
 * Use only for reads OR writes - not for read-modify-write operations.
 *
 * @as: #AddressSpace to be accessed
 * @addr: address within that address space
 * @len: pointer to length of buffer; updated on return
 * @dir: indicates the transfer direction
 */
static inline void *dma_memory_map(AddressSpace *as,
                                   dma_addr_t addr, dma_addr_t *len,
                                   DMADirection dir)
{
    hwaddr xlen = *len;
    void *p;

    p = address_space_map(as, addr, &xlen, dir == DMA_DIRECTION_FROM_DEVICE,
                          MEMTXATTRS_UNSPECIFIED);
    *len = xlen;
    return p;
}

/**
 * address_space_unmap: Unmaps a memory region previously mapped
 *                      by dma_memory_map()
 *
 * Will also mark the memory as dirty if @dir == %DMA_DIRECTION_FROM_DEVICE.
 * @access_len gives the amount of memory that was actually read or written
 * by the caller.
 *
 * @as: #AddressSpace used
 * @buffer: host pointer as returned by address_space_map()
 * @len: buffer length as returned by address_space_map()
 * @dir: indicates the transfer direction
 * @access_len: amount of data actually transferred
 */
static inline void dma_memory_unmap(AddressSpace *as,
                                    void *buffer, dma_addr_t len,
                                    DMADirection dir, dma_addr_t access_len)
{
    address_space_unmap(as, buffer, (hwaddr)len,
                        dir == DMA_DIRECTION_FROM_DEVICE, access_len);
}

#define DEFINE_LDST_DMA(_lname, _sname, _bits, _end) \
    static inline uint##_bits##_t ld##_lname##_##_end##_dma(AddressSpace *as, \
                                                            dma_addr_t addr) \
    {                                                                   \
        uint##_bits##_t val;                                            \
        dma_memory_read(as, addr, &val, (_bits) / 8);                   \
        return _end##_bits##_to_cpu(val);                               \
    }                                                                   \
    static inline void st##_sname##_##_end##_dma(AddressSpace *as,      \
                                                 dma_addr_t addr,       \
                                                 uint##_bits##_t val)   \
    {                                                                   \
        val = cpu_to_##_end##_bits(val);                                \
        dma_memory_write(as, addr, &val, (_bits) / 8);                  \
    }

static inline uint8_t ldub_dma(AddressSpace *as, dma_addr_t addr)
{
    uint8_t val;

    dma_memory_read(as, addr, &val, 1);
    return val;
}

static inline void stb_dma(AddressSpace *as, dma_addr_t addr, uint8_t val)
{
    dma_memory_write(as, 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

struct ScatterGatherEntry {
    dma_addr_t base;
    dma_addr_t len;
};

void qemu_sglist_init(QEMUSGList *qsg, DeviceState *dev, int alloc_hint,
                      AddressSpace *as);
void qemu_sglist_add(QEMUSGList *qsg, dma_addr_t base, dma_addr_t len);
void qemu_sglist_destroy(QEMUSGList *qsg);
#endif

typedef BlockAIOCB *DMAIOFunc(int64_t offset, QEMUIOVector *iov,
                              BlockCompletionFunc *cb, void *cb_opaque,
                              void *opaque);

BlockAIOCB *dma_blk_io(AioContext *ctx,
                       QEMUSGList *sg, uint64_t offset, uint32_t align,
                       DMAIOFunc *io_func, void *io_func_opaque,
                       BlockCompletionFunc *cb, void *opaque, DMADirection dir);
BlockAIOCB *dma_blk_read(BlockBackend *blk,
                         QEMUSGList *sg, uint64_t offset, uint32_t align,
                         BlockCompletionFunc *cb, void *opaque);
BlockAIOCB *dma_blk_write(BlockBackend *blk,
                          QEMUSGList *sg, uint64_t offset, uint32_t align,
                          BlockCompletionFunc *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(BlockBackend *blk, BlockAcctCookie *cookie,
                    QEMUSGList *sg, enum BlockAcctType type);

#endif