[XenPPC] Re: [PATCH] Make Linux bail out of IPI vector reset

[Jimi Xenidis <jimix@xxxxxxxxxxxxxx>]

Thanks Amos... pushed.
-JX
On Nov 21, 2006, at 10:21 PM, Amos Waterland wrote:

> Xen/PPC currently shares the mpic with dom0 Linux.  In order for
> interprocessor interrupts to work, we cannot allow Linux to reset the
> mpic (a patch for the latter was already merged) nor to reset the IPI
> vectors and change their priority.
>
> This patch introduces a feature flag, rather than trying to code a new
> function called xen_mpic_init and duplicating all the associated
> machinery it pulls in.  I tried the first approach, and it results  
> in a
> lot of code duplication, which is a worse maintenence burden than  
> this,
> I believe.  Jimi may not like this approach, but I believe it is the
> best solution until we completely virtualize the PIC at some point in
> the future.
>
> Signed-off-by: Amos Waterland <apw@xxxxxxxxxx>
>
> ---
>
>  arch/powerpc/platforms/xen/evtchn.c |    1 +
>  arch/powerpc/sysdev/mpic.c          |    4 ++++
>  include/asm-powerpc/mpic.h          |    2 ++
>  3 files changed, 7 insertions(+)
>
> diff -r 4e5b95219939 arch/powerpc/platforms/xen/evtchn.c
> --- a/arch/powerpc/platforms/xen/evtchn.c	Mon Nov 20 12:35:47 2006  
> -0500
> +++ b/arch/powerpc/platforms/xen/evtchn.c	Tue Nov 21 20:53:20 2006  
> -0500
> @@ -101,6 +101,7 @@ static __init struct mpic *xen_share_map
>
>         mpic = mpic_alloc(opic_addr,
>                           MPIC_PRIMARY | MPIC_BIG_ENDIAN |
> +                         MPIC_SKIP_IPI_INIT |
>                           MPIC_BROKEN_U3 /* | MPIC_WANTS_RESET */,
>                           0, 0, 128, 128, senses, 128, "Xen-U3-MPIC");
>         BUG_ON(mpic == NULL);
> diff -r 4e5b95219939 arch/powerpc/sysdev/mpic.c
> --- a/arch/powerpc/sysdev/mpic.c        Mon Nov 20 12:35:47 2006 -0500
> +++ b/arch/powerpc/sysdev/mpic.c        Tue Nov 21 21:08:32 2006 -0500
> @@ -741,6 +741,9 @@ void __init mpic_init(struct mpic *mpic)
>                            (MPIC_VEC_TIMER_0 + i));
>         }
>
> +        if (mpic->flags & MPIC_SKIP_IPI_INIT)
> +                goto ipi_bailout;
> +
>  	/* Initialize IPIs to our reserved vectors and mark them disabled  
> for now */
>         mpic_test_broken_ipi(mpic);
>         for (i = 0; i < 4; i++) {
> @@ -756,6 +759,7 @@ void __init mpic_init(struct mpic *mpic)
>  #endif /* CONFIG_SMP */
>         }
>
> + ipi_bailout:
>         /* Initialize interrupt sources */
>         if (mpic->irq_count == 0)
>                 mpic->irq_count = mpic->num_sources;
> diff -r 4e5b95219939 include/asm-powerpc/mpic.h
> --- a/include/asm-powerpc/mpic.h        Mon Nov 20 12:35:47 2006 -0500
> +++ b/include/asm-powerpc/mpic.h        Tue Nov 21 20:53:20 2006 -0500
> @@ -190,6 +190,8 @@ struct mpic
>  #define MPIC_BROKEN_IPI                        0x00000008
>  /* MPIC wants a reset */
>  #define MPIC_WANTS_RESET               0x00000010
> +/* Skip reset of IPI vectors during init */
> +#define MPIC_SKIP_IPI_INIT             0x00000020
>
>  /* Allocate the controller structure and setup the linux irq descs
>   * for the range if interrupts passed in. No HW initialization is

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