Re: [PATCH v4 01/40] hw/isa: check for current_cpu before generating IRQ

["Alex Bennée" <alex.bennee@linaro.org>]

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

> On 7/1/20 6:40 PM, Alex Bennée wrote:
>> 
>> Philippe Mathieu-Daudé <philmd@redhat.com> writes:
>> 
>>> On 7/1/20 3:56 PM, Alex Bennée wrote:
>>>> It's possible to trigger this function from qtest/monitor at which
>>>> point current_cpu won't point at the right place. Check it and
>>>> fall back to first_cpu if it's NULL.
>>>>
>>>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>>>> Cc: Bug 1878645 <1878645@bugs.launchpad.net>
>>>> ---
>>>>  hw/isa/lpc_ich9.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
>>>> index cd6e169d47a..791c878eb0b 100644
>>>> --- a/hw/isa/lpc_ich9.c
>>>> +++ b/hw/isa/lpc_ich9.c
>>>> @@ -439,7 +439,7 @@ static void ich9_apm_ctrl_changed(uint32_t val, void *arg)
>>>>                  cpu_interrupt(cs, CPU_INTERRUPT_SMI);
>>>>              }
>>>>          } else {
>>>> -            cpu_interrupt(current_cpu, CPU_INTERRUPT_SMI);
>>>> +            cpu_interrupt(current_cpu ? current_cpu : first_cpu, CPU_INTERRUPT_SMI);
>>>
>>> I'm not sure this change anything, as first_cpu is NULL when using
>>> qtest accelerator or none-machine, see 508b4ecc39 ("gdbstub.c: fix
>>> GDB connection segfault caused by empty machines").
>> 
>> Good point - anyway feel free to ignore - it shouldn't have been in this
>> series. It was just some random experimentation I was doing when looking
>> at that bug.
>
> See commit c781a2cc42 ("hw/i386/vmport: Allow QTest use without
> crashing") for a similar approach, but here I was thinking about
> a more generic fix, not very intrusive:
>
> -- >8 --
> diff --git a/hw/isa/apm.c b/hw/isa/apm.c
> index bce266b957..809afeb3e4 100644
> --- a/hw/isa/apm.c
> +++ b/hw/isa/apm.c
> @@ -40,7 +40,7 @@ static void apm_ioport_writeb(void *opaque, hwaddr
> addr, uint64_t val,
>      if (addr == 0) {
>          apm->apmc = val;
>
> -        if (apm->callback) {
> +        if (apm->callback && !qtest_enabled()) {
>              (apm->callback)(val, apm->arg);
>          }

But the other failure mode reported on the bug thread was via the
monitor - so I'm not sure just checking for qtest catches that.

>      } else {
> ---


-- 
Alex Bennée