Re: [PATCH] riscv: sifive_test: Allow 16-bit writes to memory region

[Alistair Francis]

On Mon, Aug 31, 2020 at 10:59 PM Nathan Chancellor
<natechancellor@gmail.com> wrote:
>
> When shutting down the machine running a mainline Linux kernel, the
> following error happens:
>
> $ build/riscv64-softmmu/qemu-system-riscv64 -bios default -M virt \
>     -display none -initrd rootfs.cpio -kernel Image -m 512m \
>     -nodefaults -serial mon:stdio
> ...
> Requesting system poweroff
> [    4.999630] reboot: Power down
> 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=0xffffffe000e76610 tp=0xffffffe0081b89c0
> 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
>
> The kernel does a 16-bit write when powering off the machine, which
> was allowed before commit 5d971f9e67 ("memory: Revert "memory: accept
> mismatching sizes in memory_region_access_valid""). Make min_access_size
> match reality so that the machine can shut down properly now.
>
> Cc: qemu-stable@nongnu.org
> Fixes: 88a07990fa ("SiFive RISC-V Test Finisher")
> Fixes: 5d971f9e67 ("memory: Revert "memory: accept mismatching sizes in 
> memory_region_access_valid"")
> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>
> Please let me know if the tags are wrong or inappropriate, this is my
> first QEMU patch.
>
>  hw/riscv/sifive_test.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> 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
>      }
>  };
>
> base-commit: 2f4c51c0f384d7888a04b4815861e6d5fd244d75
> --
> 2.28.0
>
>