Re: [PATCH v2 03/10] make qdev_disconnect_gpio_out_named() public

[Philippe Mathieu-Daudé]

Hi,

On 12/9/23 04:11, xianglai li wrote:
> It will be reused in loongarch/virt.c for unwiring
> the vcpu<->exioi interrupts for the vcpu hot-(un)plug
> cases.

Since we never had to use this, I'm surprised we really need it.

QEMU IRQs/GPIOs are similar to hardware ones, and aren't expected
to be rewired at runtime. Usually another hot-pluggable bus layer is
used, and the bus is physically wired toward the hardware.


I suppose you want to add that because a unplugged vCPU is still
receiving IRQs. The question is, why? Before unplugging, I expect
the INTC (IPI) here to be signaled a vCPU is going to be unplugged,
so maybe you are missing handling the unplug event there. See
in loongarch_ipi_writel():

    switch (addr) {
    case CORE_EN_OFF:
        s->en = val;
        break;
    case CORE_SET_OFF:
        s->status |= val;
        if (s->status != 0 && (s->status & s->en) != 0) {
            qemu_irq_raise(s->irq);
        }
        break;
    case CORE_CLEAR_OFF:
        s->status &= ~val;
        if (s->status == 0 && s->en != 0) {
            qemu_irq_lower(s->irq);
        }
        break;

Maybe you need to factor ipi_raise/lower() helpers which check cores
are available & enabled before propagating IRQ?

> Co-authored-by: "Salil Mehta" <salil.mehta@opnsrc.net>
> Cc: "Salil Mehta" <salil.mehta@opnsrc.net>
> Cc: Xiaojuan Yang <yangxiaojuan@loongson.cn>
> Cc: Song Gao <gaosong@loongson.cn>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Igor Mammedov <imammedo@redhat.com>
> Cc: Ani Sinha <anisinha@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Richard Henderson <richard.henderson@linaro.org>
> Cc: Eduardo Habkost <eduardo@habkost.net>
> Cc: Marcel Apfelbaum <marcel.apfelbaum@gmail.com>
> Cc: "Philippe Mathieu-Daudé" <philmd@linaro.org>
> Cc: Yanan Wang <wangyanan55@huawei.com>
> Cc: "Daniel P. Berrangé" <berrange@redhat.com>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Bibo Mao <maobibo@loongson.cn>
> Signed-off-by: xianglai li <lixianglai@loongson.cn>
> ---
>   hw/core/gpio.c         | 4 ++--
>   include/hw/qdev-core.h | 2 ++
>   2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/hw/core/gpio.c b/hw/core/gpio.c
> index 80d07a6ec9..4fc6409545 100644
> --- a/hw/core/gpio.c
> +++ b/hw/core/gpio.c
> @@ -143,8 +143,8 @@ qemu_irq qdev_get_gpio_out_connector(DeviceState *dev, 
> const char *name, int n)
>   
>   /* disconnect a GPIO output, returning the disconnected input (if any) */
>   
> -static qemu_irq qdev_disconnect_gpio_out_named(DeviceState *dev,
> -                                               const char *name, int n)
> +qemu_irq qdev_disconnect_gpio_out_named(DeviceState *dev,
> +                                        const char *name, int n)
>   {
>       char *propname = g_strdup_printf("%s[%d]",
>                                        name ? name : "unnamed-gpio-out", n);
> diff --git a/include/hw/qdev-core.h b/include/hw/qdev-core.h
> index 151d968238..32bb54163e 100644
> --- a/include/hw/qdev-core.h
> +++ b/include/hw/qdev-core.h
> @@ -739,6 +739,8 @@ qemu_irq qdev_get_gpio_out_connector(DeviceState *dev, 
> const char *name, int n);
>    */
>   qemu_irq qdev_intercept_gpio_out(DeviceState *dev, qemu_irq icpt,
>                                    const char *name, int n);
> +qemu_irq qdev_disconnect_gpio_out_named(DeviceState *dev,
> +                                        const char *name, int n);
>   
>   BusState *qdev_get_child_bus(DeviceState *dev, const char *name);
>