linux-kernel - Re: [PATCH 1/3] x86/Hyper-V: Set x2apic destination mode to physical when x2apic is available

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Date:   Fri, 1 Feb 2019 10:06:55 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     lantianyu1986@...il.com
Cc:     linux-kernel@...r.kernel.org, hpa@...or.com,
        mchehab+samsung@...nel.org, sashal@...nel.org,
        sthemmin@...rosoft.com, joro@...tes.org, x86@...nel.org,
        michael.h.kelley@...rosoft.com, mingo@...hat.com,
        Lan Tianyu <Tianyu.Lan@...rosoft.com>, arnd@...db.de,
        haiyangz@...rosoft.com, alex.williamson@...hat.com, bp@...en8.de,
        tglx@...utronix.de, vkuznets@...hat.com,
        gregkh@...uxfoundation.org, nicolas.ferre@...rochip.com,
        iommu@...ts.linux-foundation.org, devel@...uxdriverproject.org,
        akpm@...ux-foundation.org, davem@...emloft.net
Subject: Re: [PATCH 1/3] x86/Hyper-V: Set x2apic destination mode to physical
 when x2apic is available

On Thu, Jan 31, 2019 at 06:17:31PM +0800, lantianyu1986@...il.com wrote:
>
>

This comment needs to be indented one tab or it looks like we're outside
the funciton.

> +/*
> + * Hyper-V doesn't provide irq remapping for IO-APIC. To enable x2apic,
> + * set x2apic destination mode to physcial mode when x2apic is available
> + * and Hyper-V IOMMU driver makes sure cpus assigned with IO-APIC irqs
> + * have 8-bit APIC id.
> + */
> +# if IS_ENABLED(CONFIG_HYPERV_IOMMU)
> +	if (x2apic_supported())
> +		x2apic_phys = 1;
> +# endif

The IS_ENABLED() macro is really magical.  You could write this like so:

	if (IS_ENABLED(CONFIG_HYPERV_IOMMU) && x2apic_supported())
		x2apic_phys = 1;

It works the same and is slightly more pleasant to look at.

regards,
dan carpenter