On Thu, 12 Sep 2019 00:26:19 +1000
Michael Ellerman <m...@ellerman.id.au> wrote:
> Hi Greg,
>
Bom dia ! :)
> Couple of comments ...
>
> Greg Kurz <gr...@kaod.org> writes:
> > There's a bug in skiboot that causes the OPAL_XIVE_ALLOCATE_IRQ call
> > to return the 32-bit value 0xffffffff when OPAL has run out of IRQs.
> > Unfortunatelty, OPAL return values are signed 64-bit entities and
> > errors are supposed to be negative. If that happens, the linux code
> > confusingly treats 0xffffffff as a valid IRQ number and panics at some
> > point.
> >
> > A fix was recently merged in skiboot:
> >
> > e97391ae2bb5 ("xive: fix return value of opal_xive_allocate_irq()")
> >
> > but we need a workaround anyway to support older skiboots already
> > on the field.
> ^
> in
>
> >
> > Internally convert 0xffffffff to OPAL_RESOURCE which is the usual error
> > returned upon resource exhaustion.
>
> This should go to stable, any idea what versions it should go back to?
> Probably whenever the xive code was introduced?
>
Yes I guess so. This would mean v4.12. I'll add the appropriate stable
tag before re-posting, and address all the other remarks of course.
> > Signed-off-by: Greg Kurz <gr...@kaod.org>
> > ---
> > arch/powerpc/sysdev/xive/native.c | 13 +++++++++++--
> > 1 file changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/powerpc/sysdev/xive/native.c
> > b/arch/powerpc/sysdev/xive/native.c
> > index 37987c815913..c35583f84f9f 100644
> > --- a/arch/powerpc/sysdev/xive/native.c
> > +++ b/arch/powerpc/sysdev/xive/native.c
> > @@ -231,6 +231,15 @@ static bool xive_native_match(struct device_node *node)
> > return of_device_is_compatible(node, "ibm,opal-xive-vc");
> > }
> >
> > +static int64_t opal_xive_allocate_irq_fixup(uint32_t chip_id)
> ^ ^
> Can you use s64 here and u32 here ....
>
> Instead of calling this opal_xive_allocate_irq_fixup() and relying on
> all callers to call the fixup, can we rename the opal wrapper and leave
> this function's name unchanged, eg:
>
> -OPAL_CALL(opal_xive_allocate_irq, OPAL_XIVE_ALLOCATE_IRQ);
> +OPAL_CALL(opal_xive_allocate_irq_raw, OPAL_XIVE_ALLOCATE_IRQ);
>
>
> > +{
> > + s64 irq = opal_xive_allocate_irq(chip_id);
> > +
> > +#define XIVE_ALLOC_NO_SPACE 0xffffffff /* No possible space */
> > + return
> > + irq == XIVE_ALLOC_NO_SPACE ? OPAL_RESOURCE : irq;
> > +}
>
> I don't really like the #define and the weird indenting and so on, can
> we instead do it like:
>
> /*
> * Old versions of skiboot can incorrectly return 0xffffffff to
> * indicate no space, fix it up here.
> */
> return irq == 0xffffffff ? OPAL_RESOURCE : irq;
>
> cheers
