Re: [PATCH 1/8] keyhandler: don't pass cpu_user_regs around

[Jan Beulich <jbeulich@xxxxxxxx>]

On 11.01.2024 17:08, Andrew Cooper wrote:
> On 11/01/2024 3:49 pm, Jan Beulich wrote:
>> On 11.01.2024 16:24, Andrew Cooper wrote:
>>> On 11/01/2024 12:11 pm, Jan Beulich wrote:
>>> It does occur to me that we're trying to accommodate for two behaviours
>>> here.
>>>
>>> For a real keypress, we want to dump from the the point the interrupt
>>> hit because that's the interesting bit of stack to see.  For a SYSCTL,
>>> there's nothing, and we're using BUGFRAME_run_fn to generate one.
>> There's three forms of handle_keypress() invocations really, and hence
>> why (after having dropped the regs parameter already) I re-instated it.
> 
> Ok.  As you've done this analysis work, can you list these 3 forms?
> 
> I've clearly missed one in my analysis.

The console handler invocation is (now) using get_irq_regs(). The sysctl
handling, as said, passes guest_cpu_user_regs(). And then there are two
cases where NULL is passed, one from keypress_action() (a tasklet handler)
and the other from keyhandler_crash_action(). I'm not convinced the latter
is fully correct. The tasklet handler is used only for non-IRQ keys, and
hence only in cases where regs wouldn't have been passed to the handler
anyway.

IOW - leaving the keyhandler_crash_action() uncertainty aside, I think it
ought to be possible to do as you did suggest.

Jan