RE: [PATCH V2 1/3] x86/Hyper-V: Set x2apic destination mode to physical when x2apic is available

[Michael Kelley]

From: lantianyu1986@xxxxxxxxx <lantianyu1986@xxxxxxxxx>  Sent: Saturday, February 2, 2019 5:15 AM
> 
> 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.
> 
> Signed-off-by: Lan Tianyu <Tianyu.Lan@xxxxxxxxxxxxx>
> ---
> Change since v1:
>        - Remove redundant extern for x2apic_phys
> ---
>  arch/x86/kernel/cpu/mshyperv.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index e81a2db..4bd6d90 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -328,6 +328,16 @@ static void __init ms_hyperv_init_platform(void)
>  # ifdef CONFIG_SMP
>  	smp_ops.smp_prepare_boot_cpu = hv_smp_prepare_boot_cpu;
>  # endif
> +
> +/*
> + * 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.
> + */

Per comment from Dan Carpenter on v1 of this patch, the above comment
block should be indented one tab to line up with the "if" statement below.

Michael

> +	if (IS_ENABLED(CONFIG_HYPERV_IOMMU) && x2apic_supported())
> +		x2apic_phys = 1;
> +
>  #endif
>  }
> 
> --
> 2.7.4