Hello there, would you be so kind to give some feedback on this patch?
> On 23 May 2025, at 18:44, Kirill Martynov <stdcalll...@yandex-team.ru> wrote:
>
> Certain error conditions can trigger x86_cpu_dump_state() to output CPU state
> debug information e.g. KVM emulation failure due to misbehaving guest.
> However, if the CPU is in System Management Mode (SMM) when the assertion
> in cpu_asidx_from_attrs failure happens because:
>
> 1. In SMM mode (smm=1), the CPU must use multiple address spaces
> with a dedicated SMM address space
> 2. On machine types with softmmu, address spaces are hardcoded to 1
> (no multiple address spaces available)
>
> The assertion occurs in cpu_asidx_from_attrs() when trying to
> access memory in SMM mode with insufficient address spaces.
>
> Fix this by:
> 1. If number of address spaces is 1 always use index 0
> 2. In other cases use attr.secure for identified proper index
>
> This prevents the assertion while still providing useful debug
> output during VM shutdown errors.
>
> Stack trace of the original issue:
> #0 ... in raise () from /lib/x86_64-linux-gnu/libc.so.6
> #1 ... in abort () from /lib/x86_64-linux-gnu/libc.so.6
> #2 ... in ?? () from /lib/x86_64-linux-gnu/libc.so.6
> #3 ... in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
> #4 ... in cpu_asidx_from_attrs (cpu=cpu@entry=0x5578ca2eb340, attrs=...)
> at ../hw/core/cpu-sysemu.c:76
> #5 ... in cpu_memory_rw_debug (cpu=cpu@entry=0x5578ca2eb340,
> addr=addr@entry=2147258348, ptr=ptr@entry=0x7f5341ca373c, len=len@entry=1,
> is_write=is_write@entry=false) at ../softmmu/physmem.c:3529
> #6 ... in x86_cpu_dump_state (cs=0x5578ca2eb340,
> f=0x7f53434065c0 <_IO_2_1_stderr_>, flags=<optimized out>)
> at ../target/i386/cpu-dump.c:560
> #7 ... in kvm_cpu_exec (cpu=cpu@entry=0x5578ca2eb340)
> at ../accel/kvm/kvm-all.c:3000
> #8 ... in kvm_vcpu_thread_fn (arg=arg@entry=0x5578ca2eb340)
> at ../accel/kvm/kvm-accel-ops.c:51
> #9 ... in qemu_thread_start (args=<optimized out>)
> at ../util/qemu-thread-posix.c:505
> #10 ... in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0
> #11 ... in clone () from /lib/x86_64-linux-gnu/libc.so.6
>
> Signed-off-by: Kirill Martynov <stdcalll...@yandex-team.ru>
> ---
> target/i386/cpu.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/i386/cpu.h b/target/i386/cpu.h
> index c51e0a43d0..2616a61c87 100644
> --- a/target/i386/cpu.h
> +++ b/target/i386/cpu.h
> @@ -2507,7 +2507,7 @@ void cpu_sync_avx_hflag(CPUX86State *env);
> #ifndef CONFIG_USER_ONLY
> static inline int x86_asidx_from_attrs(CPUState *cs, MemTxAttrs attrs)
> {
> - return !!attrs.secure;
> + return cs->num_ases == 1 ? 0 : (!!attrs.secure);
> }
>
> static inline AddressSpace *cpu_addressspace(CPUState *cs, MemTxAttrs attrs)
> --
> 2.43.0
>
