Re: [PATCH v11 0/3] gdbstub and TCG plugin improvements

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

Akihiko Odaki <akihiko.odaki@daynix.com> writes:

> On 2024/02/03 22:58, Alex Bennée wrote:
>> Akihiko Odaki <akihiko.odaki@daynix.com> writes:
>> 
>>> On 2024/02/03 20:08, Alex Bennée wrote:
>>>> Akihiko Odaki <akihiko.odaki@daynix.com> writes:
>>>>
>>>>> This series extracts fixes and refactorings that can be applied
>>>>> independently from "[PATCH v9 00/23] plugins: Allow to read registers".
>>>>>
>>>>> The patch "target/riscv: Move MISA limits to class" was replaced with
>>>>> patch "target/riscv: Move misa_mxl_max to class" since I found instances
>>>>> may have different misa_ext_mask.
>>>> As this is re-based on Alistair's riscv-to-apply.next tree I'll wait
>>>> for
>>>> this to go through the RiscV trees and then re-base the plugin patches
>>>> and dropping the merged riscv patches from my tree.
>>>> In the meantime feel free to review:
>>>>     Message-Id: <20240122145610.413836-1-alex.bennee@linaro.org>
>>>>     Date: Mon, 22 Jan 2024 14:55:49 +0000
>>>>     Subject: [PATCH v3 00/21] plugin updates (register access) for 9.0 (pre-PR?)
>>>>     From: =?UTF-8?q?Alex=20Benn=C3=A9e?= <alex.bennee@linaro.org>
>>>> For:
>>>>     contrib/plugins: extend execlog to track register changes
>>>>     gdbstub: expose api to find registers
>>>> So I can add this to my maintainer omnibus series for the next PR I
>>>> send.
>>>
>>> I added one trivial comment to: "gdbstub: expose api to find registers"
>>>
>>> "contrib/plugins: extend execlog to track register changes" depends on
>>> "plugins: add an API to read registers". The comments for the patch in
>>> the following email are not addressed yet:
>>> https://lore.kernel.org/all/4b2156ed-688d-4617-b52d-200413f01156@daynix.com/
>> I don't think we need to serialise with the BQL as the structures
>> are
>> per-CPU (and created on vCPU creation).
>
> qemu_plugin_get_registers() has vcpu parameter, which can refer to a
> different vcpu the caller is on (or the caller may not be in a vcpu
> context at all).

It should only be called from the current cpu context. We can either
assert that or make it implicit like qemu_plugin_insn_disas does.
However we will need to ensure current_cpu is set before the vcpu_init
callback.

Pierrick has had to move these initialisations around for the scoreboard
work so they are now run with safe work once the thread starts.

>
>> As far as the restructuring we can move it into gdbstub later if
>> there
>> is a need to. At the moment the structure is just housekeeping for
>> plugins.
>
> Certainly we can move it later, but adding the code in the plugin
> infrastructure now won't help in that case.

-- 
Alex Bennée
Virtualisation Tech Lead @ Linaro