linux-kernel - Re: [PATCH v4 3/3] irqchip/gic-v3: Enable non-coherent redistributors/ITSes ACPI probing

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Date: Mon, 22 Jan 2024 17:18:04 +0100
From: Lorenzo Pieralisi <lpieralisi@...nel.org>
To: linux-kernel@...r.kernel.org, Marc Zyngier <maz@...nel.org>
Cc: Robin Murphy <robin.murphy@....com>,
	Mark Rutland <mark.rutland@....com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	linux-arm-kernel@...ts.infradead.org, linux-acpi@...r.kernel.org,
	acpica-devel@...ts.linux.dev, Fang Xiang <fangxiang3@...omi.com>,
	Robert Moore <robert.moore@...el.com>
Subject: Re: [PATCH v4 3/3] irqchip/gic-v3: Enable non-coherent
 redistributors/ITSes ACPI probing

On Wed, Dec 27, 2023 at 12:00:38PM +0100, Lorenzo Pieralisi wrote:

[...]

> @@ -2380,6 +2385,10 @@ gic_acpi_parse_madt_gicc(union acpi_subtable_headers *header,
>  		return -ENOMEM;
>  	gic_request_region(gicc->gicr_base_address, size, "GICR");
>  
> +	if (gic_acpi_non_coherent_flag(gicc->flags,
> +				       ACPI_MADT_GICC_NON_COHERENT))
> +		gic_data.rdists.flags |= RDIST_FLAGS_FORCE_NON_SHAREABLE;
> +

Quick question before reposting it. We run this function for
every GICC entry, I didn't add a check to make sure all GICC
entries have the same flag value, please let me know if that's
OK.

I don't think there is a point in keeping a live variable across
calls to set the flag once for all either.

Thanks,
Lorenzo

>  	gic_acpi_register_redist(gicc->gicr_base_address, redist_base);
>  	return 0;
>  }
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 54189e0e5f41..a292f2bdb693 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -283,6 +283,9 @@ static inline bool invalid_phys_cpuid(phys_cpuid_t phys_id)
>  	return phys_id == PHYS_CPUID_INVALID;
>  }
>  
> +
> +u8 __init acpi_get_madt_revision(void);
> +
>  /* Validate the processor object's proc_id */
>  bool acpi_duplicate_processor_id(int proc_id);
>  /* Processor _CTS control */
> -- 
> 2.34.1
>