Re: [PATCH 2/3] hw/intc: Add NULL pointer check on LoongArch ipi device

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 6/4/23 12:00, Song Gao wrote:
> When ipi mailbox is used, cpu index is decoded from iocsr register.
> cpu maybe does not exist. This patch adss NULL pointer check on
> ipi device.

How can that happens from a guest vcpu context?

> Signed-off-by: Song Gao <gaosong@loongson.cn>
> ---
>   hw/intc/loongarch_ipi.c | 31 +++++++++++++++++++------------
>   1 file changed, 19 insertions(+), 12 deletions(-)
> 
> diff --git a/hw/intc/loongarch_ipi.c b/hw/intc/loongarch_ipi.c
> index 0563d83a35..39e899df46 100644
> --- a/hw/intc/loongarch_ipi.c
> +++ b/hw/intc/loongarch_ipi.c
> @@ -86,11 +86,12 @@ static void ipi_send(uint64_t val)
>       /* IPI status vector */
>       data = 1 << (val & 0x1f);
>       cs = qemu_get_cpu(cpuid);
> -    cpu = LOONGARCH_CPU(cs);
> -    env = &cpu->env;
> -    address_space_stl(&env->address_space_iocsr, 0x1008,
> -                      data, MEMTXATTRS_UNSPECIFIED, NULL);
> -
> +    if (cs) {
> +        cpu = LOONGARCH_CPU(cs);
> +        env = &cpu->env;
> +        address_space_stl(&env->address_space_iocsr, 0x1008,
> +                          data, MEMTXATTRS_UNSPECIFIED, NULL);
> +    }

Is that the hardware behavior?

Could logging the invalid cpuid request be useful?

        else {

            //log or trace event here
        }
>   }