Re: [PATCH v2 09/10] xen/arm: domain_build: adjust Dom0 IRQ handling to support eSPIs

[Leonid Komarianskyi <Leonid_Komarianskyi@xxxxxxxx>]

Hello Oleksandr,

Thank you for your question.

On 23.08.25 16:02, Oleksandr Tyshchenko wrote:
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> 
> On 07.08.25 15:33, Leonid Komarianskyi wrote:
> 
> Hello Leonid
> 
>> The Dom0 configuration logic in create_dom0() has been updated
>> to account for extended SPIs when supported by the hardware and
>> enabled with CONFIG_GICV3_ESPI. These changes ensure the proper
>> calculation of the maximum number of SPIs and eSPIs available for Dom0.
>>
>> When eSPIs are supported by the hardware and CONFIG_GICV3_ESPI is
>> enabled, the maximum number of eSPI interrupts is calculated using
>> the ESPI_BASE_INTID offset (4096) and limited at 1024, with 32 IRQs
>> subtracted. To ensure compatibility with non-Dom0 domains, this
>> adjustment is applied by the toolstack during domain creation, while
>> for Dom0 it is handled directly during VGIC initialization. If eSPIs
>> are not supported, the calculation defaults to using the standard SPI
>> range, with a maximum value of 992 interrupt lines as it works now.
>>
>> Signed-off-by: Leonid Komarianskyi <leonid_komarianskyi@xxxxxxxx>
>>
>> ---
>> Changes in V2:
>> - no changes
>> ---
>>   xen/arch/arm/domain_build.c     | 10 ++++++++++
>>   xen/arch/arm/include/asm/vgic.h | 11 +++++++++++
>>   2 files changed, 21 insertions(+)
>>
>> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
>> index d91a71acfd..fa5abf2dfb 100644
>> --- a/xen/arch/arm/domain_build.c
>> +++ b/xen/arch/arm/domain_build.c
>> @@ -2055,6 +2055,16 @@ void __init create_dom0(void)
>>       /* The vGIC for DOM0 is exactly emulating the hardware GIC */
>>       dom0_cfg.arch.gic_version = XEN_DOMCTL_CONFIG_GIC_NATIVE;
>>       dom0_cfg.arch.nr_spis = VGIC_DEF_NR_SPIS;
>> +#ifdef CONFIG_GICV3_ESPI
>> +    /*
>> +     * Check if the hardware supports extended SPIs (even if the 
>> appropriate config is set).
>> +     * If not, the common SPI range will be used. Otherwise overwrite 
>> the nr_spis with the
>> +     * maximum available INTID from eSPI range. In that case, the 
>> number of regular SPIs will
>> +     * be adjusted to the maximum value during vGIC initialization.
>> +     */
>> +    if ( gic_number_espis() > 0 )
>> +        dom0_cfg.arch.nr_spis = VGIC_DEF_NR_ESPIS;
>> +#endif
> 
> I might miss something, but within the whole series, you seem not to
> update "nr_spis" field for dom0less DomUs (in dom0less-build.c). Please
> clarify the reason?
> 

Yes, I missed this because I was mostly focused on the build (with Dom0) 
that I currently have on the platform with eSPI. I rechecked the code, 
and the dom0less code has the same behavior, so I believe it should work 
similarly with the same changes in arch_create_domUs. I will update it 
in V3.

>>       dom0_cfg.arch.tee_type = tee_get_type();
>>       dom0_cfg.max_vcpus = dom0_max_vcpus();
>>
> 
> [snip]

Best regards,
Leonid