Similarly to commit 158b659451 with the APB PnP registers, guests
can crash QEMU when writting to the AHB PnP registers:

  $ echo 'writeb 0xfffff042 69' | qemu-system-sparc -M leon3_generic -S -bios /etc/magic -qtest stdio
  [I 1571938309.932255] OPENED
  [R +0.063474] writeb 0xfffff042 69
  Segmentation fault (core dumped)

  (gdb) bt
  #0  0x0000000000000000 in  ()
  #1  0x0000562999110df4 in memory_region_write_with_attrs_accessor
      (mr=mr@entry=0x56299aa28ea0, addr=66, value=value@entry=0x7fff6abe13b8, size=size@entry=1, shift=<optimized out>, mask=mask@entry=255, attrs=...) at memory.c:503
  #2  0x000056299911095e in access_with_adjusted_size
      (addr=addr@entry=66, value=value@entry=0x7fff6abe13b8, size=size@entry=1, access_size_min=<optimized out>, access_size_max=<optimized out>, access_fn=access_fn@entry=
      0x562999110d70 <memory_region_write_with_attrs_accessor>, mr=0x56299aa28ea0, attrs=...) at memory.c:539
  #3  0x0000562999114fba in memory_region_dispatch_write (mr=mr@entry=0x56299aa28ea0, addr=66, data=<optimized out>, op=<optimized out>, attrs=attrs@entry=...) at memory.c:1482
  #4  0x00005629990c0860 in flatview_write_continue
      (fv=fv@entry=0x56299aa7d8a0, addr=addr@entry=4294963266, attrs=..., ptr=ptr@entry=0x7fff6abe1540, len=len@entry=1, addr1=<optimized out>, l=<optimized out>, mr=0x56299aa28ea0)
      at include/qemu/host-utils.h:164
  #5  0x00005629990c0a76 in flatview_write (fv=0x56299aa7d8a0, addr=4294963266, attrs=..., buf=0x7fff6abe1540, len=1) at exec.c:3165
  #6  0x00005629990c4c1b in address_space_write (as=<optimized out>, addr=<optimized out>, attrs=..., attrs@entry=..., buf=buf@entry=0x7fff6abe1540, len=len@entry=1) at exec.c:3256
  #7  0x000056299910f807 in qtest_process_command (chr=chr@entry=0x5629995ee920 <qtest_chr>, words=words@entry=0x56299acfcfa0) at qtest.c:437

Instead of crashing, log the access as unimplemented.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
---
 hw/misc/grlib_ahb_apb_pnp.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/misc/grlib_ahb_apb_pnp.c b/hw/misc/grlib_ahb_apb_pnp.c
index e230e25363..72a8764776 100644
--- a/hw/misc/grlib_ahb_apb_pnp.c
+++ b/hw/misc/grlib_ahb_apb_pnp.c
@@ -136,8 +136,15 @@ static uint64_t grlib_ahb_pnp_read(void *opaque, hwaddr offset, unsigned size)
     return ahb_pnp->regs[offset >> 2];
 }
 
+static void grlib_ahb_pnp_write(void *opaque, hwaddr addr,
+                                uint64_t val, unsigned size)
+{
+    qemu_log_mask(LOG_UNIMP, "%s not implemented\n", __func__);
+}
+
 static const MemoryRegionOps grlib_ahb_pnp_ops = {
     .read       = grlib_ahb_pnp_read,
+    .write      = grlib_ahb_pnp_write,
     .endianness = DEVICE_BIG_ENDIAN,
 };
 
-- 
2.21.1

Le 3/31/20 à 12:50 PM, Philippe Mathieu-Daudé a écrit :
> Similarly to commit 158b659451 with the APB PnP registers, guests
> can crash QEMU when writting to the AHB PnP registers:
> 
>    $ echo 'writeb 0xfffff042 69' | qemu-system-sparc -M leon3_generic -S -bios /etc/magic -qtest stdio
>    [I 1571938309.932255] OPENED
>    [R +0.063474] writeb 0xfffff042 69
>    Segmentation fault (core dumped)
> 
>    (gdb) bt
>    #0  0x0000000000000000 in  ()
>    #1  0x0000562999110df4 in memory_region_write_with_attrs_accessor
>        (mr=mr@entry=0x56299aa28ea0, addr=66, value=value@entry=0x7fff6abe13b8, size=size@entry=1, shift=<optimized out>, mask=mask@entry=255, attrs=...) at memory.c:503
>    #2  0x000056299911095e in access_with_adjusted_size
>        (addr=addr@entry=66, value=value@entry=0x7fff6abe13b8, size=size@entry=1, access_size_min=<optimized out>, access_size_max=<optimized out>, access_fn=access_fn@entry=
>        0x562999110d70 <memory_region_write_with_attrs_accessor>, mr=0x56299aa28ea0, attrs=...) at memory.c:539
>    #3  0x0000562999114fba in memory_region_dispatch_write (mr=mr@entry=0x56299aa28ea0, addr=66, data=<optimized out>, op=<optimized out>, attrs=attrs@entry=...) at memory.c:1482
>    #4  0x00005629990c0860 in flatview_write_continue
>        (fv=fv@entry=0x56299aa7d8a0, addr=addr@entry=4294963266, attrs=..., ptr=ptr@entry=0x7fff6abe1540, len=len@entry=1, addr1=<optimized out>, l=<optimized out>, mr=0x56299aa28ea0)
>        at include/qemu/host-utils.h:164
>    #5  0x00005629990c0a76 in flatview_write (fv=0x56299aa7d8a0, addr=4294963266, attrs=..., buf=0x7fff6abe1540, len=1) at exec.c:3165
>    #6  0x00005629990c4c1b in address_space_write (as=<optimized out>, addr=<optimized out>, attrs=..., attrs@entry=..., buf=buf@entry=0x7fff6abe1540, len=len@entry=1) at exec.c:3256
>    #7  0x000056299910f807 in qtest_process_command (chr=chr@entry=0x5629995ee920 <qtest_chr>, words=words@entry=0x56299acfcfa0) at qtest.c:437
> 
> Instead of crashing, log the access as unimplemented.
> 
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>   hw/misc/grlib_ahb_apb_pnp.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/hw/misc/grlib_ahb_apb_pnp.c b/hw/misc/grlib_ahb_apb_pnp.c
> index e230e25363..72a8764776 100644
> --- a/hw/misc/grlib_ahb_apb_pnp.c
> +++ b/hw/misc/grlib_ahb_apb_pnp.c
> @@ -136,8 +136,15 @@ static uint64_t grlib_ahb_pnp_read(void *opaque, hwaddr offset, unsigned size)
>       return ahb_pnp->regs[offset >> 2];
>   }
>   
> +static void grlib_ahb_pnp_write(void *opaque, hwaddr addr,
> +                                uint64_t val, unsigned size)
> +{
> +    qemu_log_mask(LOG_UNIMP, "%s not implemented\n", __func__);
> +}
> +
>   static const MemoryRegionOps grlib_ahb_pnp_ops = {
>       .read       = grlib_ahb_pnp_read,
> +    .write      = grlib_ahb_pnp_write,
>       .endianness = DEVICE_BIG_ENDIAN,
>   };
>   
> 

Reviewed-by: KONRAD Frederic <frederic.konrad@adacore.com>