Re: [Xen-devel] [PATCH 4/9] x86/IRQ: desc->affinity should strictly represent the requested value

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, Apr 29, 2019 at 05:24:39AM -0600, Jan Beulich wrote:
> desc->arch.cpu_mask reflects the actual set of target CPUs. Don't ever
> fiddle with desc->affinity itself, except to store caller requested
> values.
> 
> This renders both set_native_irq_info() uses (which weren't using proper
> locking anyway) redundant - drop the function altogether.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

> 
> --- a/xen/arch/x86/io_apic.c
> +++ b/xen/arch/x86/io_apic.c
> @@ -1042,7 +1042,6 @@ static void __init setup_IO_APIC_irqs(vo
>              SET_DEST(entry, logical, cpu_mask_to_apicid(TARGET_CPUS));
>              spin_lock_irqsave(&ioapic_lock, flags);
>              __ioapic_write_entry(apic, pin, 0, entry);
> -            set_native_irq_info(irq, TARGET_CPUS);
>              spin_unlock_irqrestore(&ioapic_lock, flags);
>          }
>      }
> @@ -2251,7 +2250,6 @@ int io_apic_set_pci_routing (int ioapic,
>  
>      spin_lock_irqsave(&ioapic_lock, flags);
>      __ioapic_write_entry(ioapic, pin, 0, entry);
> -    set_native_irq_info(irq, TARGET_CPUS);
>      spin_unlock(&ioapic_lock);
>  
>      spin_lock(&desc->lock);
> --- a/xen/arch/x86/irq.c
> +++ b/xen/arch/x86/irq.c
> @@ -572,11 +572,16 @@ int assign_irq_vector(int irq, const cpu
>  
>      spin_lock_irqsave(&vector_lock, flags);
>      ret = __assign_irq_vector(irq, desc, mask ?: TARGET_CPUS);
> -    if (!ret) {
> +    if ( !ret )
> +    {
>          ret = desc->arch.vector;
> -        cpumask_copy(desc->affinity, desc->arch.cpu_mask);
> +        if ( mask )
> +            cpumask_copy(desc->affinity, mask);
> +        else
> +            cpumask_setall(desc->affinity);

I guess it's fine to use setall instead of copying the cpu online map
here?

AFAICT __assign_irq_vector already filters offline CPUs from the
passed mask.

Thanks, Roger.

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