Re: [PATCH v4] hw/dma/pl330: Add memory region to replace default

[Philippe Mathieu-Daudé]

On 8/18/21 4:47 AM, Wen, Jianxian wrote:
> Add configurable property memory region which can connect with IOMMU region 
> to support SMMU translate.
> 
> Signed-off-by: Jianxian Wen <jianxian.wen@verisilicon.com>
> ---
> v3 -> v4 (after review of Philippe Mathieu-Daudé):
>  - Avoid adding unnecessary AS, add AS if we connect with IOMMU region.
> v2 -> v3 (after review of Philippe Mathieu-Daudé):
>  - Refine code to comply with code style, update error message if memory link 
> is not set.
> v1 -> v2 (after review of Peter Maydell):
>  - Data access use dma_memory_read/write functions, update function 
> AddressSpace* parameter.
> 
>  hw/dma/pl330.c | 21 +++++++++++++++++----
>  1 file changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/dma/pl330.c b/hw/dma/pl330.c
> index 944ba29..8ae56c7 100644
> --- a/hw/dma/pl330.c
> +++ b/hw/dma/pl330.c
> @@ -269,6 +269,9 @@ struct PL330State {
>      uint8_t num_faulting;
>      uint8_t periph_busy[PL330_PERIPH_NUM];
>  
> +    /* Memory region that DMA operation access */
> +    MemoryRegion *mem_mr;
> +    AddressSpace *mem_as;
>  };
>  
>  #define TYPE_PL330 "pl330"
> @@ -1108,7 +1111,7 @@ static inline const PL330InsnDesc 
> *pl330_fetch_insn(PL330Chan *ch)
>      uint8_t opcode;
>      int i;
>  
> -    dma_memory_read(&address_space_memory, ch->pc, &opcode, 1);
> +    dma_memory_read(ch->parent->mem_as, ch->pc, &opcode, 1);
>      for (i = 0; insn_desc[i].size; i++) {
>          if ((opcode & insn_desc[i].opmask) == insn_desc[i].opcode) {
>              return &insn_desc[i];
> @@ -1122,7 +1125,7 @@ static inline void pl330_exec_insn(PL330Chan *ch, const 
> PL330InsnDesc *insn)
>      uint8_t buf[PL330_INSN_MAXSIZE];
>  
>      assert(insn->size <= PL330_INSN_MAXSIZE);
> -    dma_memory_read(&address_space_memory, ch->pc, buf, insn->size);
> +    dma_memory_read(ch->parent->mem_as, ch->pc, buf, insn->size);
>      insn->exec(ch, buf[0], &buf[1], insn->size - 1);
>  }
>  
> @@ -1186,7 +1189,7 @@ static int pl330_exec_cycle(PL330Chan *channel)
>      if (q != NULL && q->len <= pl330_fifo_num_free(&s->fifo)) {
>          int len = q->len - (q->addr & (q->len - 1));
>  
> -        dma_memory_read(&address_space_memory, q->addr, buf, len);
> +        dma_memory_read(s->mem_as, q->addr, buf, len);
>          trace_pl330_exec_cycle(q->addr, len);
>          if (trace_event_get_state_backends(TRACE_PL330_HEXDUMP)) {
>              pl330_hexdump(buf, len);
> @@ -1217,7 +1220,7 @@ static int pl330_exec_cycle(PL330Chan *channel)
>              fifo_res = pl330_fifo_get(&s->fifo, buf, len, q->tag);
>          }
>          if (fifo_res == PL330_FIFO_OK || q->z) {
> -            dma_memory_write(&address_space_memory, q->addr, buf, len);
> +            dma_memory_write(s->mem_as, q->addr, buf, len);
>              trace_pl330_exec_cycle(q->addr, len);
>              if (trace_event_get_state_backends(TRACE_PL330_HEXDUMP)) {
>                  pl330_hexdump(buf, len);
> @@ -1562,6 +1565,13 @@ static void pl330_realize(DeviceState *dev, Error 
> **errp)
>                            "dma", PL330_IOMEM_SIZE);
>      sysbus_init_mmio(SYS_BUS_DEVICE(dev), &s->iomem);
>  
> +    if (s->mem_mr && (s->mem_mr != get_system_memory())) {
> +        s->mem_as = g_malloc0(sizeof(AddressSpace));
> +        address_space_init(s->mem_as, s->mem_mr, s->mem_mr->name);

I'm not sure about the description. Anyhow, don't access MemoryRegion
internals, use memory_region_name().

> +    } else {
> +        s->mem_as = &address_space_memory;
> +    }

A bit convoluted but I like the result.

Maybe easier to follow as:

    if (!s->mem_mr) {
        error_setg(errp, "'memory' link is not set");
        return;
    } else if (s->mem_mr == get_system_memory()) {
        /* Avoid creating new AS for system memory. */
        s->mem_as = &address_space_memory;
    } else {
        g_autofree char *desc =
              g_strdup_printf("%s-as", memory_region_name(s->mem_mr);

        s->mem_as = g_new0(AddressSpace, 1);
        address_space_init(s->mem_as, s->mem_mr, desc);
    }

'desc' is optional, I don't mind if you prefer the simpler:

        address_space_init(s->mem_as, s->mem_mr,
                           memory_region_name(s->mem_mr));

>      s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, pl330_exec_cycle_timer, s);
>  
>      s->cfg[0] = (s->mgr_ns_at_rst ? 0x4 : 0) |
> @@ -1656,6 +1666,9 @@ static Property pl330_properties[] = {
>      DEFINE_PROP_UINT8("rd_q_dep", PL330State, rd_q_dep, 16),
>      DEFINE_PROP_UINT16("data_buffer_dep", PL330State, data_buffer_dep, 256),
>  
> +    DEFINE_PROP_LINK("memory", PL330State, mem_mr,
> +                     TYPE_MEMORY_REGION, MemoryRegion *),
> +
>      DEFINE_PROP_END_OF_LIST(),
>  };
>  
>