Re: [PATCH] memory: Revert "memory: accept mismatching sizes in memory_region_access_valid"

[Nathan Chancellor <natechancellor@gmail.com>]

On Sun, Aug 30, 2020 at 08:24:15AM +0100, Mark Cave-Ayland wrote:
> On 30/08/2020 07:49, Nathan Chancellor wrote:
> 
> > Unfortunately, it does not. I applied it on top of latest
> > git (ac8b279f13865d1a4f1958d3bf34240c1c3af90d) and I can still
> > reproduce my failure. Is it possible that type of fix is needed
> > in a RISC-V specific driver?
> > 
> > Would you like me to comment on the Launchpad bug as well?
> 
> Hi Nathan,
> 
> I came up with a quick patch to enable some logging to catch memory accesses being
> refused for a similar bug report at
> https://bugs.launchpad.net/qemu/+bug/1886318/comments/13.
> 
> Can you apply the same change to your tree and report any messages on stderr as you
> do your board reboot test?
> 
> 
> ATB,
> 
> Mark.

Thanks Mark, that helped.

...
[    3.807738] reboot: Power down
invalid size: riscv.sifive.test addr 0 size: 2
sbi_trap_error: hart0: trap handler failed (error -2)
sbi_trap_error: hart0: mcause=0x0000000000000007 mtval=0x0000000000100000
sbi_trap_error: hart0: mepc=0x000000008000d4cc mstatus=0x0000000000001822
sbi_trap_error: hart0: ra=0x000000008000999e sp=0x0000000080015c78
sbi_trap_error: hart0: gp=0xffffffe000e765d0 tp=0xffffffe0081c0000
sbi_trap_error: hart0: s0=0x0000000080015c88 s1=0x0000000000000040
sbi_trap_error: hart0: a0=0x0000000000000000 a1=0x0000000080004024
sbi_trap_error: hart0: a2=0x0000000080004024 a3=0x0000000080004024
sbi_trap_error: hart0: a4=0x0000000000100000 a5=0x0000000000005555
sbi_trap_error: hart0: a6=0x0000000000004024 a7=0x0000000080011158
sbi_trap_error: hart0: s2=0x0000000000000000 s3=0x0000000080016000
sbi_trap_error: hart0: s4=0x0000000000000000 s5=0x0000000000000000
sbi_trap_error: hart0: s6=0x0000000000000001 s7=0x0000000000000000
sbi_trap_error: hart0: s8=0x0000000000000000 s9=0x0000000000000000
sbi_trap_error: hart0: s10=0x0000000000000000 s11=0x0000000000000008
sbi_trap_error: hart0: t0=0x0000000000000000 t1=0x0000000000000000
sbi_trap_error: hart0: t2=0x0000000000000000 t3=0x0000000000000000
sbi_trap_error: hart0: t4=0x0000000000000000 t5=0x0000000000000000
sbi_trap_error: hart0: t6=0x0000000000000000

With this diff, I can successfully shut down the board. No idea if that
is valid or not though.

Cheers,
Nathan

============================================================

diff --git a/hw/riscv/sifive_test.c b/hw/riscv/sifive_test.c
index 0c78fb2c93..8c70dd69df 100644
--- a/hw/riscv/sifive_test.c
+++ b/hw/riscv/sifive_test.c
@@ -59,7 +59,7 @@ static const MemoryRegionOps sifive_test_ops = {
     .write = sifive_test_write,
     .endianness = DEVICE_NATIVE_ENDIAN,
     .valid = {
-        .min_access_size = 4,
+        .min_access_size = 2,
         .max_access_size = 4
     }
 };