Re: [PATCH v2 3/4] xen/riscv: implement basic aplic_preinit()

[Oleksii Kurochko <oleksii.kurochko@gmail.com>]

[-- Attachment #1: Type: text/plain, Size: 3801 bytes --]


On 3/27/25 8:39 AM, Jan Beulich wrote:
> On 26.03.2025 17:49, Oleksii Kurochko wrote:
>> On 3/26/25 4:19 PM, Jan Beulich wrote:
>>> On 25.03.2025 18:36, Oleksii Kurochko wrote:
>>>> Introduce preinitialization stuff for the RISC-V Advanced Platform-Level
>>>> Interrupt Controller (APLIC) in Xen:
>>>>    - Implementing the APLIC pre-initialization function (`aplic_preinit()`),
>>>>      ensuring that only one APLIC instance is supported in S mode.
>>>>    - Initialize APLIC's correspoinding DT node.
>>>>    - Declaring the DT device match table for APLIC.
>>>>    - Setting `aplic_info.hw_version` during its declaration.
>>>>    - Declaring an APLIC device.
>>>>
>>>> Since Microchip originally developed aplic.c [1], an internal discussion
>>>> with them led to the decision to use the MIT license instead of the default
>>>> GPL-2.0-only.
>>>>
>>>> [1]https://gitlab.com/xen-project/people/olkur/xen/-/commit/7cfb4bd4748ca268142497ac5c327d2766fb342d
>>>>
>>>> Signed-off-by: Romain Caritey<Romain.Caritey@microchip.com>
>>>> Signed-off-by: Oleksii Kurochko<oleksii.kurochko@gmail.com>
>>> You recall that From: != 1st S-o-b is unusual, and wants some explanation.
>>> IOW it's unclear who the original author of this patch is.
>> I'm not 100% sure who should be the author. Such patch doesn't exist before but I took the changes
>> based on the changes mentioned in commit message as [1].
>>
>> If you think that the author should be Romain, I am okay with that.
> I can't sensibly form an opinion here. This needs settling between him and you.
>  From your reply I'm not even convinced his S-o-b is legitimately there then.
> You may want to use another, less standard tag in such a case (like the
> Co-developed-by: that I've seen in use here and there) to still give credit to
> him.

I'll have a conversation with Romain and then just re-send the patch.

>
>>>> --- /dev/null
>>>> +++ b/xen/arch/riscv/aplic.c
>>>> @@ -0,0 +1,49 @@
>>>> +/* SPDX-License-Identifier: MIT */
>>>> +
>>>> +/*
>>>> + * xen/arch/riscv/aplic.c
>>>> + *
>>>> + * RISC-V Advanced Platform-Level Interrupt Controller support
>>>> + *
>>>> + * Copyright (c) 2023-2024 Microchip.
>>>> + * Copyright (c) 2024-2025 Vates
>>>> + */
>>>> +
>>>> +#include <xen/errno.h>
>>>> +#include <xen/init.h>
>>>> +#include <xen/types.h>
>>>> +
>>>> +#include <asm/device.h>
>>>> +#include <asm/intc.h>
>>>> +
>>>> +static struct intc_info aplic_info = {
>>>> +    .hw_version = INTC_APLIC
>>>> +};
>>> Is this going to be written to (much) post-init? IOW - __read_mostly or
>>> even __ro_after_init?
>> I think that __read_mostly would be better because intc_info structure in the future
>> will contain member "void *private". And in `private` it can be a data which can
>> be changed.
> You mean the pointer can change? Or merely what it points to, i.e. ...
>
>> For example, `private` can contain an aplic_priv structure:
>> struct aplic_priv {
>>       /* number of irqs */
>>       uint32_t   nr_irqs;
>>
>>       /* base physical address and size */
>>       paddr_t    paddr_start;
>>       paddr_t    paddr_end;
>>       uint64_t   size;
>>
>>       /* registers */
>>       struct aplic_regs   *regs;
>>
>>       /* imsic configuration */
>>       const struct imsic_config *imsic_cfg;
>> };
>>
>> and regs from aplic_priv structure can be changed in runtime.
> ... the contents of such a struct? In this latter case the struct instance
> here can still be __ro_after_init as long as the pointer is set from an
> __init function.

I meant that the data will be changed. The pointer will be initialized once
in the following way:
static struct intc_info aplic_info = {
     .hw_version = INTC_APLIC,
     .private = &aplic
};

I will update for both structures __ro_after_init() then.

Thanks for clarification.

~ Oleksii

[-- Attachment #2: Type: text/html, Size: 5357 bytes --]