On 05/05/16 14:40, Marc Zyngier wrote: > On Thu, 5 May 2016 14:22:06 +0100 > Jon Hunter <[email protected]> wrote: > >> Hi Marc, >> >> On 05/05/16 13:06, Marc Zyngier wrote: >>> Hi Jon, >>> >>> On 04/05/16 17:25, Jon Hunter wrote: >>>> Setting the interrupt type for private peripheral interrupts (PPIs) may >>>> not be supported by a given GIC because it is IMPLEMENTATION DEFINED >>>> whether this is allowed. There is no way to know if setting the type is >>>> supported for a given GIC and so the value written is read back to >>>> verify it matches the desired configuration. If it does not match then >>>> an error is return. >>>> >>>> There are cases where the interrupt configuration read from firmware >>>> (such as a device-tree blob), has been incorrect and hence >>>> gic_configure_irq() has returned an error. This error has gone >>>> undetected because the error code returned was ignored but the interrupt >>>> still worked fine because the configuration for the interrupt could not >>>> be overwritten. >>>> >>>> Given that this has done undetected and that failing to set the >>>> configuration for a PPI may not be a catastrophic, don't return an error >>>> but WARN if we fail to configure a PPI. This will allows us to fix up >>>> any places in the kernel where we should be checking the return status >>>> and maintain backward compatibility with firmware images that may have >>>> incorrect PPI configurations. >>>> >>>> Signed-off-by: Jon Hunter <[email protected]> >>>> Acked-by: Marc Zyngier <[email protected]> >>>> --- >>>> drivers/irqchip/irq-gic-common.c | 11 +++++++---- >>>> 1 file changed, 7 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/drivers/irqchip/irq-gic-common.c >>>> b/drivers/irqchip/irq-gic-common.c >>>> index ffff5a45f1e3..9fa92a17225c 100644 >>>> --- a/drivers/irqchip/irq-gic-common.c >>>> +++ b/drivers/irqchip/irq-gic-common.c >>>> @@ -56,12 +56,15 @@ int gic_configure_irq(unsigned int irq, unsigned int >>>> type, >>>> >>>> /* >>>> * Write back the new configuration, and possibly re-enable >>>> - * the interrupt. If we fail to write a new configuration, >>>> - * return an error. >>>> + * the interrupt. WARN if we fail to write a new configuration >>>> + * and return an error if we failed to write the configuration >>>> + * for an SPI. If we fail to write the configuration for a PPI >>>> + * this is most likely because the GIC does not allow us to set >>>> + * the configuration and so it is not a catastrophic failure. >>>> */ >>>> writel_relaxed(val, base + GIC_DIST_CONFIG + confoff); >>>> - if (readl_relaxed(base + GIC_DIST_CONFIG + confoff) != val) >>>> - ret = -EINVAL; >>>> + if (WARN_ON(readl_relaxed(base + GIC_DIST_CONFIG + confoff) != val)) >>>> + ret = irq < 32 ? 0 : -EINVAL; >>>> >>>> if (sync_access) >>>> sync_access(); >>>> >>> >>> I'm going to slightly backpedal on that one: >>> >>> When running in non-secure mode, you can reconfigure secure interrupts >> >> Do you mean 'cannot'? > > Yes, sorry. > >>> (for obvious reasons). But you don't know which mode you're running in >>> either. A typical example is the arch timer, which requests both secure >>> and non-secure interrupts, because we cannot know which side of the CPU >>> we're running on. In the non-secure case, we end-up with a splat that >>> is rather undeserved. >> >> Yes seems sensible. >> >>> So I'm tempted to tone down the splat in the PPI case like this: >>> >>> diff --git a/drivers/irqchip/irq-gic-common.c >>> b/drivers/irqchip/irq-gic-common.c >>> index 083c303..1605e42 100644 >>> --- a/drivers/irqchip/irq-gic-common.c >>> +++ b/drivers/irqchip/irq-gic-common.c >>> @@ -63,8 +63,17 @@ int gic_configure_irq(unsigned int irq, unsigned int >>> type, >>> * the configuration and so it is not a catastrophic failure. >>> */ >>> writel_relaxed(val, base + GIC_DIST_CONFIG + confoff); >>> - if (WARN_ON(readl_relaxed(base + GIC_DIST_CONFIG + confoff) != val)) >>> - ret = irq < 32 ? 0 : -EINVAL; >>> + oldval = readl_relaxed(base + GIC_DIST_CONFIG + confoff); >>> + if (oldval != val) { >>> + if (irq < 32) { >>> + pr_warn("GIC: PPI%d is either secure or >>> misconfigured\n", >>> + irq - 16); >>> + ret = 0; >>> + } else { >>> + WARN_ON(1); >>> + ret = -EINVAL; >>> + } >>> + } >>> >>> if (sync_access) >>> sync_access(); >>> >>> Thoughts? >> >> That is fine with me. Do you want me to re-spin or do you want to apply >> your change on top? However, before I re-spin would like to get your >> thoughts on patches 13-17. > > I can squash this into your own patch if you're OK with it. I'll reply > to your other patches shortly, as I have a number of comments there.
Yes that is fine with me. Cheers Jon
