Re: [PATCH v4 09/12] xen/arm: domain_build/dom0less-build: adjust domains config to support eSPIs

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

On 27.08.25 21:24, Leonid Komarianskyi wrote:

Hello Leonid

> The Dom0 and DomUs logic for the dom0less configuration in create_dom0() and
> arch_create_domUs() 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
> to Dom0 and DomUs in dom0less setups.
>
> 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 is limited to 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 or DomUs in 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 currently.
>
> Signed-off-by: Leonid Komarianskyi <leonid_komarianskyi@xxxxxxxx>
>
> ---
> Changes in V4:
> - consolidated the eSPI and SPI logic into a new inline function,
>    vgic_def_nr_spis. Without eSPI support (either due to config being
>    disabled or hardware not supporting it), it will return the regular SPI
>    range, as it works currently. There are no functional changes compared
>    with the previous patch version
> - removed VGIC_DEF_MAX_SPI macro, to reduce the number of ifdefs
very good, thanks, only NIT below

Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>



> Changes in V3:
> - renamed macro VGIC_DEF_NR_ESPIS to more appropriate VGIC_DEF_MAX_SPI
> - added eSPI initialization for dom0less setups
> - fixed comment with mentions about dom0less builds
> - fixed formatting for lines with more than 80 symbols
> - updated commit message
>
> Changes in V2:
> - no changes
> ---
>   xen/arch/arm/dom0less-build.c   |  2 +-
>   xen/arch/arm/domain_build.c     |  2 +-
>   xen/arch/arm/include/asm/vgic.h | 21 +++++++++++++++++++++
>   3 files changed, 23 insertions(+), 2 deletions(-)
>
> diff --git a/xen/arch/arm/dom0less-build.c b/xen/arch/arm/dom0less-build.c
> index 69b9ea22ce..02d5559102 100644
> --- a/xen/arch/arm/dom0less-build.c
> +++ b/xen/arch/arm/dom0less-build.c
> @@ -285,7 +285,7 @@ void __init arch_create_domUs(struct dt_device_node *node,
>       {
>           int vpl011_virq = GUEST_VPL011_SPI;
>   
> -        d_cfg->arch.nr_spis = VGIC_DEF_NR_SPIS;
> +        d_cfg->arch.nr_spis = vgic_def_nr_spis();
>   
>           /*
>            * The VPL011 virq is GUEST_VPL011_SPI, unless direct-map is
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index d91a71acfd..39eea0be00 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -2054,7 +2054,7 @@ 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;
> +    dom0_cfg.arch.nr_spis = vgic_def_nr_spis();
>       dom0_cfg.arch.tee_type = tee_get_type();
>       dom0_cfg.max_vcpus = dom0_max_vcpus();
>   
> diff --git a/xen/arch/arm/include/asm/vgic.h b/xen/arch/arm/include/asm/vgic.h
> index fb4cea73eb..11f9d216eb 100644
> --- a/xen/arch/arm/include/asm/vgic.h
> +++ b/xen/arch/arm/include/asm/vgic.h
> @@ -355,6 +355,27 @@ extern void vgic_check_inflight_irqs_pending(struct vcpu 
> *v,
>   /* Default number of vGIC SPIs. 32 are substracted to cover local IRQs. */
>   #define VGIC_DEF_NR_SPIS (min(gic_number_lines(), VGIC_MAX_IRQS) - 32)
>   
> +static inline unsigned int vgic_def_nr_spis(void)
> +{
> +#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
> +     * returns the maximum eSPI INTID, supported by HW GIC, subtracted by 32.
NIT: s/returns/return ...


> +     * For non-Dom0 domains, the toolstack or arch_create_domUs function
> +     * applies the same adjustment to cover local IRQs (please, see comment
> +     * for macro that is used for regular SPIs - VGIC_DEF_NR_SPIS).
 ... I am not 100% sure, that I follow the wording "For non-Dom0 
domains, the toolstack or arch_create_domUs ...". Did you perhaps mean:
For Dom0 and started at boot time DomUs ...?

 We will
> +     * add back this value during VGIC initialization. This ensures consistent
> +     * handling for Dom0 and other domains. For the regular SPI range 
> interrupts
> +     * in this case, the maximum value of VGIC_DEF_NR_SPIS will be used.
> +     */
> +    if ( gic_number_espis() > 0 )
> +        return ESPI_BASE_INTID + min(gic_number_espis(), 1024U) - 32;
> +#endif
> +
> +    return VGIC_DEF_NR_SPIS;
> +}
> +
>   extern bool vgic_is_valid_line(struct domain *d, unsigned int virq);
>   
>   static inline bool vgic_is_spi(struct domain *d, unsigned int virq)