On 05/12/2020 15:09, Philippe Mathieu-Daudé wrote:

> Per the "NCR89C105 Chip Specification" referenced in the header:
> 
>                    Chip-level Address Map
> 
>    ------------------------------------------------------------------
>    | 1D0 0000 ->   | Counter/Timers                        | W,D    |
>    |   1DF FFFF    |                                       |        |
>    ...
> 
>    The address map indicated the allowed accesses at each address.
>    [...] W indicates a word access, and D indicates a double-word
>    access.
> 
> The SLAVIO timer controller is implemented expecting 32-bit accesses.
> Commit a3d12d073e1 restricted the memory accesses to 32-bit, while
> the device allows 64-bit accesses.
> 
> This was not an issue until commit 5d971f9e67 which reverted
> ("memory: accept mismatching sizes in memory_region_access_valid").
> 
> Fix by renaming .valid MemoryRegionOps as .impl, and add the valid
> access range (W -> 4, D -> 8).
> 
> Since commit 21786c7e598 ("memory: Log invalid memory accesses")
> this class of bug can be quickly debugged displaying 'guest_errors'
> accesses, as:
> 
>    $ qemu-system-sparc -M SS-20 -m 256 -bios ss20_v2.25_rom -serial stdio -d guest_errors
> 
>    Power-ON Reset
>    Invalid access at addr 0x0, size 8, region 'timer-1', reason: invalid size (min:4 max:4)
> 
>    $ qemu-system-sparc -M SS-20 -m 256 -bios ss20_v2.25_rom -monitor stdio -S
>    (qemu) info mtree
>    address-space: memory
>      0000000000000000-ffffffffffffffff (prio 0, i/o): system
>        ...
>        0000000ff1300000-0000000ff130000f (prio 0, i/o): timer-1
>               ^^^^^^^^^                                 ^^^^^^^
>                     \ memory region base address and name /
> 
>    (qemu) info qtree
>    bus: main-system-bus
>      dev: slavio_timer, id ""              <-- device type name
>        gpio-out "sysbus-irq" 17
>        num_cpus = 1 (0x1)
>        mmio 0000000ff1310000/0000000000000014
>        mmio 0000000ff1300000/0000000000000010 <--- base address
>        mmio 0000000ff1301000/0000000000000010
>        mmio 0000000ff1302000/0000000000000010
>        ...
> 
> Reported-by: Yap KV <email address hidden>
> Buglink: https://bugs.launchpad.net/bugs/1906905
> Fixes: a3d12d073e1 ("slavio_timer: convert to memory API")
> Signed-off-by: Philippe Mathieu-Daudé <email address hidden>
> ---
> Cc: Benoit Canet <email address hidden>
> Cc: <email address hidden>
> Signed-off-by: Philippe Mathieu-Daudé <email address hidden>
> ---
>   hw/timer/slavio_timer.c | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/hw/timer/slavio_timer.c b/hw/timer/slavio_timer.c
> index 5b2d20cb6a5..03e33fc5926 100644
> --- a/hw/timer/slavio_timer.c
> +++ b/hw/timer/slavio_timer.c
> @@ -331,6 +331,10 @@ static const MemoryRegionOps slavio_timer_mem_ops = {
>       .write = slavio_timer_mem_writel,
>       .endianness = DEVICE_NATIVE_ENDIAN,
>       .valid = {
> +        .min_access_size = 4,
> +        .max_access_size = 8,
> +    },
> +    .impl = {
>           .min_access_size = 4,
>           .max_access_size = 4,
>       },

I don't really use the proprietary Sun ROMs here, but the fix looks good to me:

Reviewed-by: Mark Cave-Ayland <email address hidden>

It's probably also worth a CC to qemu-stable to try and also get this into 5.1.1 to 
accompany the related TCX issues.


ATB,

Mark.