linux-kernel - Re: [PATCH 1/3] acpi/processor: fix evaluating

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Date:   Mon, 21 Nov 2022 15:02:30 +0100
From:   Jan Beulich <jbeulich@...e.com>
To:     Roger Pau Monne <roger.pau@...rix.com>
Cc:     xen-devel@...ts.xenproject.org, jgross@...e.com,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>, Alex Chiang <achiang@...com>,
        Venkatesh Pallipadi <venkatesh.pallipadi@...el.com>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] acpi/processor: fix evaluating _PDC method when
 running as Xen dom0

On 21.11.2022 11:21, Roger Pau Monne wrote:
> @@ -47,6 +49,15 @@ static bool __init processor_physically_present(acpi_handle handle)
>  		return false;
>  	}
>  
> +	if (xen_initial_domain())
> +		/*
> +		 * When running as a Xen dom0 the number of processors Linux
> +		 * sees can be different from the real number of processors on
> +		 * the system, and we still need to execute _PDC for all of
> +		 * them.
> +		 */
> +		return xen_processor_present(acpi_id);
> +
>  	type = (acpi_type == ACPI_TYPE_DEVICE) ? 1 : 0;
>  	cpuid = acpi_get_cpuid(handle, type, acpi_id);

We had to deal with this in our XenoLinux forward ports as well, but at
the time it appeared upstream I decided to make use of acpi_get_apicid()
(which meanwhile was renamed to acpi_get_phys_id()). Wouldn't than be an
option, eliminating the need for a Xen-specific new function?

Jan