[PATCH 2/3] irqchip/gic-v3: allocate one SGI for MSHV

[Wei Liu]

On Tue, Nov 25, 2025 at 05:01:23PM +0000, Anirudh Raybharam wrote:
> From: Anirudh Rayabharam <anirudh at anirudhrb.com>
[...]
>  /* SMCCC hypercall parameters */
>  #define HV_SMCCC_FUNC_NUMBER	1
>  #define HV_FUNC_ID	ARM_SMCCC_CALL_VAL(			\
> diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
> index 3de351e66ee8..56013dd0564c 100644
> --- a/drivers/irqchip/irq-gic-v3.c
> +++ b/drivers/irqchip/irq-gic-v3.c
> @@ -35,6 +35,7 @@
>  #include <asm/exception.h>
>  #include <asm/smp_plat.h>
>  #include <asm/virt.h>
> +#include <asm/mshyperv.h>
>  
>  #include "irq-gic-common.h"
>  
> @@ -1456,8 +1457,24 @@ static void __init gic_smp_init(void)
>  		.fwnode		= gic_data.fwnode,
>  		.param_count	= 1,
>  	};
> +	/* Register all 8 non-secure SGIs */
> +	const int NR_SMP_SGIS = 8;
> +	int nr_sgis = NR_SMP_SGIS;
>  	int base_sgi;
>  
> +	/*
> +	 * Allocate one more SGI for use by Hyper-V. This is only needed when
> +	 * Linux is running in a parent partition. Hyper-V will use this interrupt
> +	 * to notify the parent partition of intercepts.
> +	 *
> +	 * When running on Hyper-V, it is okay to use SGIs 8-15. They're not reserved
> +	 * for secure firmware.
> +	 */
> +#if IS_ENABLED(CONFIG_HYPERV)
> +	if (hv_parent_partition())
> +		nr_sgis += 1;
> +#endif
> +

This is far too intrusive. Let's take Marc's feedback and work with the
hypervisor team to resolve this properly.

Wei