LIU Zhiwei <zhiwei_liu@c-sky.com> 於 2021年6月28日 週一 下午3:40寫道：

>
> On 2021/6/28 下午3:23, Frank Chang wrote:
>
> LIU Zhiwei <zhiwei_liu@c-sky.com> 於 2021年6月28日 週一 下午3:17寫道：
>
>>
>> On 2021/6/26 下午8:56, Frank Chang wrote:
>>
>> On Wed, Jun 16, 2021 at 10:56 AM LIU Zhiwei <zhiwei_liu@c-sky.com> wrote:
>>
>>>
>>> On 6/13/21 6:10 PM, Frank Chang wrote:
>>>
>>> LIU Zhiwei <zhiwei_liu@c-sky.com> 於 2021年4月9日 週五 下午3:57寫道：
>>>
>>> +static void riscv_clic_realize(DeviceState *dev, Error **errp)
>>>> +{
>>>> +    RISCVCLICState *clic = RISCV_CLIC(dev);
>>>> +    size_t harts_x_sources = clic->num_harts * clic->num_sources;
>>>> +    int irqs, i;
>>>> +
>>>> +    if (clic->prv_s && clic->prv_u) {
>>>> +        irqs = 3 * harts_x_sources;
>>>> +    } else if (clic->prv_s || clic->prv_u) {
>>>> +        irqs = 2 * harts_x_sources;
>>>> +    } else {
>>>> +        irqs = harts_x_sources;
>>>> +    }
>>>> +
>>>> +    clic->clic_size = irqs * 4 + 0x1000;
>>>> +    memory_region_init_io(&clic->mmio, OBJECT(dev), &riscv_clic_ops,
>>>> clic,
>>>> +                          TYPE_RISCV_CLIC, clic->clic_size);
>>>> +
>>>> +    clic->clicintip = g_new0(uint8_t, irqs);
>>>> +    clic->clicintie = g_new0(uint8_t, irqs);
>>>> +    clic->clicintattr = g_new0(uint8_t, irqs);
>>>> +    clic->clicintctl = g_new0(uint8_t, irqs);
>>>> +    clic->active_list = g_new0(CLICActiveInterrupt, irqs);
>>>> +    clic->active_count = g_new0(size_t, clic->num_harts);
>>>> +    clic->exccode = g_new0(uint32_t, clic->num_harts);
>>>> +    clic->cpu_irqs = g_new0(qemu_irq, clic->num_harts);
>>>> +    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &clic->mmio);
>>>> +
>>>> +    /* Allocate irq through gpio, so that we can use qtest */
>>>> +    qdev_init_gpio_in(dev, riscv_clic_set_irq, irqs);
>>>> +    qdev_init_gpio_out(dev, clic->cpu_irqs, clic->num_harts);
>>>> +
>>>> +    for (i = 0; i < clic->num_harts; i++) {
>>>> +        RISCVCPU *cpu = RISCV_CPU(qemu_get_cpu(i));
>>>>
>>>
>>> As spec says:
>>>   Smaller single-core systems might have only a CLIC,
>>>   while multicore systems might have a CLIC per-core and a single shared
>>> PLIC.
>>>   The PLIC xeip signals are treated as hart-local interrupt sources by
>>> the CLIC at each core.
>>>
>>> It looks like it's possible to have one CLIC instance per core.
>>>
>>> If you want to delivery an interrupt to one hart, you should encode the
>>> IRQ by the interrupt number
>>> , the hart number and the interrupt target privilege, then set the irq.
>>>
>>> I think how to calculate the hart number is the task of PLIC and it can
>>> make use of "hartid-base"
>>> to calculate it.
>>>
>>> Thanks,
>>> Zhiwei
>>>
>>
>> Hi Zhiwei,
>>
>> What I mean is if there are multiple CLIC instances, each per core (CLIC
>> spec allows that).
>> If you try to bind CLIC with CPU index start from 0,
>> it will be impossible for CLIC instance to bind CPU from index other than
>> 0.
>>
>> For example, for 4 cores system, it's possible to have 4 CLIC instances:
>>   * CLIC 0 binds to CPU 0
>>   * CLIC 1 binds to CPU 1
>>   * CLIC 2 binds to CPU 2
>>   * CLIC 3 binds to CPU 3
>>
>> and that's why I said it's possible to pass an extra "hartid-base" just
>> like PLIC.
>> I know most of hardid are calculated by the requesing address, so most
>> hartid usages should be fine.
>> But I saw two places using qemu_get_cpu(),
>>
>> which may cause the problem for the scenario I describe above:
>> i.e. riscv_clic_next_interrupt() and riscv_clic_realize() as my original
>> reply.
>>
>> So what's the problem here?
>>
>> Currently all cores share the same CLIC instance. Do you want to give
>> each core  a CLIC instance?
>>
> Yes, that's what I mean, which should be supported as what spec says[1]:
>   The CLIC complements the PLIC. Smaller single-core systems might have
> only a CLIC,
>   while multicore systems might have *a CLIC per-core* and a single
> shared PLIC.
>   The PLIC xeip signals are treated as hart-local interrupt sources by the
> CLIC at each core.
>
> [1]
> https://github.com/riscv/riscv-fast-interrupt/blob/646310a5e4ae055964b4680f12c1c04a7cc0dd56/clic.adoc#12-clic-versus-plic
>
> Thanks,
> Frank Chang
>
>
> If we give each core a CLIC instance, it is not convenient to access the
> shared memory, such as 0x0-0x1000.
> Which CLIC instance should contain this memory region?
>
What do you mean by: "access the shared memory" here?
I thought the memory region is defined during CLIC's creation?
So it should depend on the platform that creates CLIC instances.

Thanks,
Frank Chang


> Thanks,
> Zhiwei
>
>
>> Thanks,
>> Zhiwei
>>
> Regards,
>> Frank Chang
>>
>>
>>> However if you try to bind CPU reference start from index i = 0.
>>> It's not possible for each per-core CLIC to bind their own CPU instance
>>> in multicore system
>>> as they have to bind from CPU 0.
>>>
>>> I'm not sure if we add a new "hartid-base" property just like what
>>> SiFive PLIC is
>>> implemented would be a good idea or not.
>>>
>>>
>>> Regards,
>>> Frank Chang
>>>
>>>
>>>> +        qemu_irq irq = qemu_allocate_irq(riscv_clic_cpu_irq_handler,
>>>> +                                         &cpu->env, 1);
>>>> +        qdev_connect_gpio_out(dev, i, irq);
>>>> +        cpu->env.clic = clic;
>>>> +    }
>>>> +}
>>>> +
>>>>
>>>>
>>>>