linux-kernel - Re: [PATCH 8/9] x86/apic: match destination id with destination mode

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Message-ID: <86802c440906261421g77fd0e50j7dfdbbdcc7c0b8eb@mail.gmail.com>
Date:	Fri, 26 Jun 2009 14:21:54 -0700
From:	Yinghai Lu <yhlu.kernel@...il.com>
To:	"Pan, Jacob jun" <jacob.jun.pan@...el.com>,
	Ingo Molnar <mingo@...e.hu>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: Re: [PATCH 8/9] x86/apic: match destination id with destination mode

On Thu, Jun 25, 2009 at 5:15 PM, Pan, Jacob jun<jacob.jun.pan@...el.com> wrote:
> From 791a44040dde6670f90a729cf91ed302d84b875a Mon Sep 17 00:00:00 2001
> From: Jacob Pan <jacob.jun.pan@...el.com>
> Date: Tue, 12 May 2009 10:51:08 -0700
> Subject: [PATCH] x86/apic: match destination id with destination mode
>
> current code assigns logical destination IDs regardless of destination modes, this is not a problem since we only use logical delivery so far. but it could be a problem with platforms only supports physical mode
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...el.com>
> ---
>  arch/x86/kernel/apic/io_apic.c |   27 +++++++++++++++++++--------
>  1 files changed, 19 insertions(+), 8 deletions(-)
>
> diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
> index 4d0216f..c84dc3d 100644
> --- a/arch/x86/kernel/apic/io_apic.c
> +++ b/arch/x86/kernel/apic/io_apic.c
> @@ -1431,7 +1431,10 @@ int setup_ioapic_entry(int apic_id, int irq,
>        } else {
>                entry->delivery_mode = apic->irq_delivery_mode;
>                entry->dest_mode = apic->irq_dest_mode;
> -               entry->dest = destination;
> +               if (apic->irq_dest_mode)
> +                       entry->dest = destination;
> +               else    /* physical ID of BSP */
> +                       entry->dest = boot_cpu_id;
>                entry->vector = vector;
>        }
>
> @@ -1576,7 +1579,10 @@ static void __init setup_timer_IRQ0_pin(unsigned int apic_id, unsigned int pin,
>         */
>        entry.dest_mode = apic->irq_dest_mode;
>        entry.mask = 0;                 /* don't mask IRQ for edge */
> -       entry.dest = apic->cpu_mask_to_apicid(apic->target_cpus());
> +       if (!apic->irq_dest_mode)
> +               entry.dest = boot_cpu_id;       /* physical apic id */
> +       else
> +               entry.dest = apic->cpu_mask_to_apicid(apic->target_cpus());
>        entry.delivery_mode = apic->irq_delivery_mode;
>        entry.polarity = 0;
>        entry.trigger = 0;
> @@ -2343,7 +2349,8 @@ set_ioapic_affinity_irq_desc(struct irq_desc *desc, const struct cpumask *mask)
>        dest = set_desc_affinity(desc, mask);
>        if (dest != BAD_APICID) {
>                /* Only the high 8 bits are valid. */
> -               dest = SET_APIC_LOGICAL_ID(dest);
> +               if (apic->irq_dest_mode)
> +                       dest = SET_APIC_LOGICAL_ID(dest);
>                __target_IO_APIC_irq(irq, dest, cfg);
>                ret = 0;
>        }
> @@ -3273,9 +3280,11 @@ static int msi_compose_msg(struct pci_dev *pdev, unsigned int irq, struct msi_ms
>        err = assign_irq_vector(irq, cfg, apic->target_cpus());
>        if (err)
>                return err;
> -
> -       dest = apic->cpu_mask_to_apicid_and(cfg->domain, apic->target_cpus());
> -
> +       if (apic->irq_dest_mode)
> +               dest = apic->cpu_mask_to_apicid_and(cfg->domain,
> +                                               apic->target_cpus());
> +       else
> +               dest = boot_cpu_id;
>        if (irq_remapped(irq)) {
>                struct irte irte;
>                int ir_index;
> @@ -3339,8 +3348,10 @@ static int set_msi_irq_affinity(unsigned int irq, const struct cpumask *mask)
>        struct irq_cfg *cfg;
>        struct msi_msg msg;
>        unsigned int dest;
> -
> -       dest = set_desc_affinity(desc, mask);
> +       if (apic->irq_dest_mode)
> +               dest = set_desc_affinity(desc, mask);
> +       else
> +               dest = boot_cpu_id;
>        if (dest == BAD_APICID)
>                return -1;
>

for physical flat mode

apic->cpu_mask_to_apicid() is

static unsigned int physflat_cpu_mask_to_apicid(const struct cpumask *cpumask)
{
        int cpu;

        /*
         * We're using fixed IRQ delivery, can only return one phys APIC ID.
         * May as well be the first.
         */
        cpu = cpumask_first(cpumask);
        if ((unsigned)cpu < nr_cpu_ids)
                return per_cpu(x86_cpu_to_apicid, cpu);
        else
                return BAD_APICID;
}


so this patch will put all ioapic routing to boot_cpu_id what is that?
how can you assume that is is apic id.?
that is NOT apic id.

the patch is totally wrong.

Nacked-by: Yinghai Lu <yinghai@...nel.org>


YH
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