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SubjectRe: [v5 3/3] x86, irq: Define a global vector for VT-d Posted-Interrupts
On Mon, 18 May 2015, Feng Wu wrote:
> diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h
> index 0f5fb6b..9866065 100644
> --- a/arch/x86/include/asm/hardirq.h
> +++ b/arch/x86/include/asm/hardirq.h
> @@ -14,6 +14,7 @@ typedef struct {
> #endif
> #ifdef CONFIG_HAVE_KVM
> unsigned int kvm_posted_intr_ipis;
> + unsigned int kvm_posted_intr_wakeup_ipis;

So now we have another IPI with statistics and nothing which makes it
accessible. kvm_posted_intr_ipis lacks a printout in
arch_show_interrupts() as well.

> #ifdef CONFIG_HAVE_KVM
> +void (*wakeup_handler_callback)(void);
> +EXPORT_SYMBOL_GPL(wakeup_handler_callback);
> +

The naming sucks. Which wakeup?

As this is kvm specific, it should have a kvm_ prefix. And it should
tell what it actually does:

kvm_posted_intr_wakeup_handler

Hmm?

> /*
> * Handler for POSTED_INTERRUPT_VECTOR.
> */
> @@ -256,6 +259,26 @@ __visible void smp_kvm_posted_intr_ipi(struct pt_regs *regs)
>
> set_irq_regs(old_regs);
> }
> +
> +/*
> + * Handler for POSTED_INTERRUPT_WAKEUP_VECTOR.
> + */
> +__visible void smp_kvm_posted_intr_wakeup_ipi(struct pt_regs *regs)
> +{
> + struct pt_regs *old_regs = set_irq_regs(regs);
> +
> + entering_ack_irq();
> +
> + inc_irq_stat(kvm_posted_intr_wakeup_ipis);
> +
> + if (wakeup_handler_callback)
> + wakeup_handler_callback();

Why do we need a conditional here?

staic void dummy_handler(void) { }
static void *kvm_posted_intr_wakeup_handler = dummy_handler;

void kvm_set_posted_intr_wakeup_handler(void (*handler)(void))
{
if (handler)
kvm_posted_intr_wakeup_handler = handler;
else
kvm_posted_intr_wakeup_handler = dummy_handler;
}

avoids the conditional in the exception handler....

Thanks,

tglx


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