Re: [Qemu-devel] [PATCH v2 for 1.6 1/2] memory: Provide separate handling of unassigned io ports accesses

[Anthony Liguori <aliguori@us.ibm.com>]

Jan Kiszka <jan.kiszka@siemens.com> writes:

> Accesses to unassigned io ports shall return -1 on read and be ignored
> on write. Ensure these properties via dedicated ops, decoupling us from
> the memory core's handling of unassigned accesses.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

Please top-post.

Regards,

Anthony Liguori

> ---
>
> Changes in v2:
>  - avoid breakage in ioport.h for user build
>
>  exec.c                |    3 ++-
>  include/exec/ioport.h |    4 ++++
>  ioport.c              |   16 ++++++++++++++++
>  3 files changed, 22 insertions(+), 1 deletions(-)
>
> diff --git a/exec.c b/exec.c
> index 3ca9381..9ed598f 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1820,7 +1820,8 @@ static void memory_map_init(void)
>      address_space_init(&address_space_memory, system_memory, "memory");
>  
>      system_io = g_malloc(sizeof(*system_io));
> -    memory_region_init(system_io, NULL, "io", 65536);
> +    memory_region_init_io(system_io, NULL, &unassigned_io_ops, NULL, "io",
> +                          65536);
>      address_space_init(&address_space_io, system_io, "I/O");
>  
>      memory_listener_register(&core_memory_listener, &address_space_memory);
> diff --git a/include/exec/ioport.h b/include/exec/ioport.h
> index bdd4e96..b3848be 100644
> --- a/include/exec/ioport.h
> +++ b/include/exec/ioport.h
> @@ -45,6 +45,10 @@ typedef struct MemoryRegionPortio {
>  
>  #define PORTIO_END_OF_LIST() { }
>  
> +#ifndef CONFIG_USER_ONLY
> +extern const MemoryRegionOps unassigned_io_ops;
> +#endif
> +
>  void cpu_outb(pio_addr_t addr, uint8_t val);
>  void cpu_outw(pio_addr_t addr, uint16_t val);
>  void cpu_outl(pio_addr_t addr, uint32_t val);
> diff --git a/ioport.c b/ioport.c
> index 79b7f1a..707cce8 100644
> --- a/ioport.c
> +++ b/ioport.c
> @@ -44,6 +44,22 @@ typedef struct MemoryRegionPortioList {
>      MemoryRegionPortio ports[];
>  } MemoryRegionPortioList;
>  
> +static uint64_t unassigned_io_read(void *opaque, hwaddr addr, unsigned size)
> +{
> +    return -1ULL;
> +}
> +
> +static void unassigned_io_write(void *opaque, hwaddr addr, uint64_t val,
> +                                unsigned size)
> +{
> +}
> +
> +const MemoryRegionOps unassigned_io_ops = {
> +    .read = unassigned_io_read,
> +    .write = unassigned_io_write,
> +    .endianness = DEVICE_NATIVE_ENDIAN,
> +};
> +
>  void cpu_outb(pio_addr_t addr, uint8_t val)
>  {
>      LOG_IOPORT("outb: %04"FMT_pioaddr" %02"PRIx8"\n", addr, val);
> -- 
> 1.7.3.4