Re: [Qemu-devel] [PATCH] memory: Set notdirty_mem_ops validator

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 9/2/19 3:26 AM, Tony Nguyen wrote:
> Existing read rejecting validator was mistakenly cleared.
> 
> Reads dispatched to io_mem_notdirty then segfaults as there is no read
> handler.
> 
> Signed-off-by: Tony Nguyen <tony.nguyen@bt.com>
> ---
>  exec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/exec.c b/exec.c
> index 1df966d17a..05d664541f 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -2796,12 +2796,12 @@ static bool notdirty_mem_accepts(void *opaque, hwaddr addr,
>  
>  static const MemoryRegionOps notdirty_mem_ops = {
>      .write = notdirty_mem_write,
> -    .valid.accepts = notdirty_mem_accepts,
>      .endianness = DEVICE_NATIVE_ENDIAN,
>      .valid = {
>          .min_access_size = 1,
>          .max_access_size = 8,
>          .unaligned = false,
> +        .accepts = notdirty_mem_accepts,

I'm surprised the compiler doesn't emit any warning...

>      },
>      .impl = {
>          .min_access_size = 1,
> 

mcayland provided a verbose backtrace running Solaris, can we amend it
to this commit?

Thread 4 "qemu-system-spa" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7ffff1d44700 (LWP 23749)]
0x0000000000000000 in ?? ()
(gdb) bt
#0  0x0000000000000000 in  ()
#1  0x00005555557eae4c in memory_region_read_with_attrs_accessor
(mr=0x55555633d360 <io_mem_notdirty>, addr=531677168,
value=0x7ffff1d42eb8, size=4, shift=0, mask=4294967295, attrs=...)
    at /home/build/src/qemu/git/qemu/memory.c:461
#2  0x00005555557eb1c4 in access_with_adjusted_size (addr=531677168,
value=0x7ffff1d42eb8, size=4, access_size_min=1, access_size_max=8,
access_fn=
    0x5555557eadf0 <memory_region_read_with_attrs_accessor>,
mr=0x55555633d360 <io_mem_notdirty>, attrs=...) at
/home/build/src/qemu/git/qemu/memory.c:559
#3  0x00005555557edeb0 in memory_region_dispatch_read1
(mr=0x55555633d360 <io_mem_notdirty>, addr=531677168,
pval=0x7ffff1d42eb8, size=4, attrs=...) at
/home/build/src/qemu/git/qemu/memory.c:1429
#4  0x00005555557edf47 in memory_region_dispatch_read (mr=0x55555633d360
<io_mem_notdirty>, addr=531677168, pval=0x7ffff1d42eb8, op=MO_32,
attrs=...) at /home/build/src/qemu/git/qemu/memory.c:1451
#5  0x0000555555803846 in io_readx (env=0x5555564b15c0,
iotlbentry=0x7fffe831e190, mmu_idx=2, addr=1880588272,
retaddr=140736889685638, access_type=MMU_DATA_LOAD, op=MO_32)
    at /home/build/src/qemu/git/qemu/accel/tcg/cputlb.c:923
#6  0x00005555558063ca in load_helper (full_load=0x555555805ffb
<full_be_ldul_mmu>, code_read=false, op=MO_BEUL,
retaddr=140736889685638, oi=162, addr=1880588272, env=0x5555564b15c0)
    at /home/build/src/qemu/git/qemu/accel/tcg/cputlb.c:1346
#7  0x00005555558063ca in full_be_ldul_mmu (env=0x5555564b15c0,
addr=1880588272, oi=162, retaddr=140736889685638) at
/home/build/src/qemu/git/qemu/accel/tcg/cputlb.c:1469
#8  0x0000555555806665 in helper_be_ldul_mmu (env=0x5555564b15c0,
addr=1880588272, oi=162, retaddr=140736889685638) at
/home/build/src/qemu/git/qemu/accel/tcg/cputlb.c:1476
#9  0x00007fffdc5106cd in code_gen_buffer ()
#10 0x00005555558280da in cpu_tb_exec (cpu=0x5555564a8820,
itb=0x7fffdc50f7c0 <code_gen_buffer+5306259>) at
/home/build/src/qemu/git/qemu/accel/tcg/cpu-exec.c:172
#11 0x0000555555828ec7 in cpu_loop_exec_tb (cpu=0x5555564a8820,
tb=0x7fffdc50f7c0 <code_gen_buffer+5306259>, last_tb=0x7ffff1d43598,
tb_exit=0x7ffff1d43590) at
/home/build/src/qemu/git/qemu/accel/tcg/cpu-exec.c:620
#12 0x00005555558291d5 in cpu_exec (cpu=0x5555564a8820) at
/home/build/src/qemu/git/qemu/accel/tcg/cpu-exec.c:731
#13 0x00005555557dc460 in tcg_cpu_exec (cpu=0x5555564a8820) at
/home/build/src/qemu/git/qemu/cpus.c:1445
#14 0x00005555557dc76b in qemu_tcg_rr_cpu_thread_fn (arg=0x5555564a8820)
at /home/build/src/qemu/git/qemu/cpus.c:1547
#15 0x0000555555c562d4 in qemu_thread_start (args=0x5555564c8020) at
/home/build/src/qemu/git/qemu/util/qemu-thread-posix.c:502
#16 0x00007ffff6296fa3 in start_thread (arg=<optimized out>) at
pthread_create.c:486
#17 0x00007ffff61c74cf in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:95
(gdb)

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>