Re: [Xen-devel] [PATCH v4 10/27] ARM: GICv3: forward pending LPIs to guests

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 03/04/17 21:28, Andre Przywara wrote:
> diff --git a/xen/arch/arm/gic-v3-lpi.c b/xen/arch/arm/gic-v3-lpi.c
> index d3ee141..ad89863 100644
> --- a/xen/arch/arm/gic-v3-lpi.c
> +++ b/xen/arch/arm/gic-v3-lpi.c
> @@ -125,6 +125,48 @@ uint64_t gicv3_get_redist_address(unsigned int cpu, bool 
> use_pta)
>          return per_cpu(lpi_redist, cpu).redist_id << 16;
>  }
>
> +/*
> + * Handle incoming LPIs, which are a bit special, because they are potentially
> + * numerous and also only get injected into guests. Treat them specially here,
> + * by just looking up their target vCPU and virtual LPI number and hand it
> + * over to the injection function.
> + */
> +void do_LPI(unsigned int lpi)
> +{
> +    struct domain *d;
> +    union host_lpi *hlpip, hlpi;
> +    struct vcpu *vcpu;
I forgot to mention, you will need irq_enter here and irq_exit in the 
return path.
> +    WRITE_SYSREG32(lpi, ICC_EOIR1_EL1);
> +
> +    hlpip = gic_get_host_lpi(lpi);
> +    if ( !hlpip )
> +        return;
> +
> +    hlpi.data = read_u64_atomic(&hlpip->data);
> +
> +    /* Unmapped events are marked with an invalid LPI ID. */
> +    if ( hlpi.virt_lpi == INVALID_LPI )
> +        return;
> +
> +    d = rcu_lock_domain_by_id(hlpi.dom_id);
> +    if ( !d )
> +        return;
> +
> +    /* Make sure we don't step beyond the vcpu array. */
> +    if ( hlpi.vcpu_id >= d->max_vcpus )
> +    {
> +        rcu_unlock_domain(d);
> +        return;
> +    }
> +
> +    vcpu = d->vcpu[hlpi.vcpu_id];
> +
> +    vgic_vcpu_inject_irq(vcpu, hlpi.virt_lpi);
> +
> +    rcu_unlock_domain(d);
> +}
> +
>  static int gicv3_lpi_allocate_pendtable(uint64_t *reg)
>  {
>      uint64_t val;
> diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
> index 3ed6f81..a6037d4 100644
> --- a/xen/arch/arm/gic.c
> +++ b/xen/arch/arm/gic.c
> @@ -709,7 +709,13 @@ void gic_interrupt(struct cpu_user_regs *regs, int is_fiq)
>              do_IRQ(regs, irq, is_fiq);
>              local_irq_disable();
>          }
> -        else if (unlikely(irq < 16))
> +#ifdef CONFIG_HAS_ITS
> +        else if ( is_lpi(irq) )
> +        {
You probably want to enable IRQs here...

> +            do_LPI(irq);
... and disable here as we do the SPIs/PPIs.

Cheers,

--
Julien Grall

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