Re: [Xen-devel] [PATCH qemu-traditional] ioreq: Support 32-bit default_ioport_* accesses

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Fri, May 20, 2016 at 09:52:40AM -0400, Boris Ostrovsky wrote:
> Recent changes in ACPICA (specifically, Linux commit 66b1ed5aa8dd ("ACPICA:
> ACPI 2.0, Hardware: Add access_width/bit_offset support for
> acpi_hw_write()") result in guests issuing 32-bit accesses to IO space.
> 
> QEMU needs to be able to handle them.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> ---
>  vl.c | 15 ++++++++-------
>  1 file changed, 8 insertions(+), 7 deletions(-)
> 
> diff --git a/vl.c b/vl.c
> index c864e7d..79d3ab5 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -350,17 +350,18 @@ static void default_ioport_writew(void *opaque, 
> uint32_t address, uint32_t data)
>  
>  static uint32_t default_ioport_readl(void *opaque, uint32_t address)
>  {
> -#ifdef DEBUG_UNUSED_IOPORT
> -    fprintf(stderr, "unused inl: port=0x%04x\n", address);
> -#endif
> -    return 0xffffffff;
> +    uint32_t data;
> +    data = default_ioport_readw(opaque, address) & 0xffff;
> +    address = (address + 2) & (MAX_IOPORTS - 1);

I'm not very familiar with how hardware behaves, but shouldn't we return
some sort of invalid result (~0) and log when the port wraps?

Wei.

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