Re: [PATCH 3/5] hw/intc/loongson_ipi: Implement IOCSR address space for MIPS

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

On 8/5/24 15:06, Jiaxun Yang wrote:
> Implement IOCSR address space get functions for MIPS/Loongson CPUs.
> 
> For MIPS/Loongson without IOCSR (i.e. Loongson-3A1000), get_cpu_iocsr_as
> will return as null, and send_ipi_data will fail with MEMTX_DECODE_ERROR,
> which matches expected behavior on hardware.
> 
> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
> ---
> I understand that there was a review comment stating that I shouldn't
> use TARGET_* macros in device drivers. But I still think this is the
> best way to handle architectural difference. There are many TARGET_*
> usages in hw/virtio for similiar purpose.
> ---
>   hw/intc/loongson_ipi.c | 39 ++++++++++++++++++++++++++++++---------
>   1 file changed, 30 insertions(+), 9 deletions(-)


>   static MemTxResult loongson_ipi_readl(void *opaque, hwaddr addr,
> @@ -56,18 +61,35 @@ static MemTxResult loongson_ipi_readl(void *opaque, hwaddr addr,
>       return MEMTX_OK;
>   }
>   
> -static void send_ipi_data(CPULoongArchState *env, uint64_t val, hwaddr addr,
> +static AddressSpace *get_cpu_iocsr_as(CPUState *cpu)
> +{
> +#ifdef TARGET_LOONGARCH64
> +    return LOONGARCH_CPU(cpu)->env.address_space_iocsr;
> +#endif
> +#ifdef TARGET_MIPS
> +    if (ase_lcsr_available(&MIPS_CPU(cpu)->env)) {
> +        return &MIPS_CPU(cpu)->env.iocsr.as;
> +    }
> +#endif
> +    return NULL;
> +}
> +
> +static MemTxResult send_ipi_data(CPUState *cpu, uint64_t val, hwaddr addr,
>                             MemTxAttrs attrs)
>   {
>       int i, mask = 0, data = 0;
> +    AddressSpace *iocsr_as = get_cpu_iocsr_as(cpu);

LoongsonIPI should have an array of CPUState[] and MemoryRegion[].
(Or maybe add them to IPICore.)
Expose them as QOM link properties.

Caller wire them while creating the LoongsonIPI.
Then loongson_ipi_realize() resolves them once.
No need to call get_cpu_iocsr_as() and ipi_getcpu() for each MMIO
access IMO.

> +
> +    if (!iocsr_as) {
> +        return MEMTX_DECODE_ERROR;
> +    }