Re: [Xen-devel] [PATCH v6 12/36] ARM: GICv3: forward pending LPIs to guests

[Julien Grall <julien.grall@xxxxxxx>]

Hi Andre,

On 04/07/2017 06:32 PM, Andre Przywara wrote:
> diff --git a/xen/arch/arm/gic-v3-lpi.c b/xen/arch/arm/gic-v3-lpi.c
> index 292f2d0..5f3fe2c 100644
> --- a/xen/arch/arm/gic-v3-lpi.c
> +++ b/xen/arch/arm/gic-v3-lpi.c
> @@ -136,6 +136,62 @@ 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.
> + * Please note that LPIs are edge-triggered only, also have no active state,
> + * so spurious interrupts on the host side are no issue (we can just ignore
> + * them).
> + * Also a guest cannot expect that firing interrupts that haven't been
> + * fully configured yet will reach the CPU, so we don't need to care about
> + * this special case.
> + */
> +void gicv3_do_LPI(unsigned int lpi)
> +{
> +    struct domain *d;
> +    union host_lpi *hlpip, hlpi;
> +    struct vcpu *vcpu;
As mentioned on the last 2 previous version, you will need irq_enter and 
irq_exit in the return path. So the common code know you are in an 
interrupt handler (see in_irq()).
> +
> +    /* EOI the LPI already. */
> +    WRITE_SYSREG32(lpi, ICC_EOIR1_EL1);
> +
> +    /* Find out if a guest mapped something to this physical LPI. */
> +    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. We can safely
> +     * ignore them, as they have no further state and no-one can expect
> +     * to see them if they have not been mapped.
> +     */
> +    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];
> +
> +    /* Check if the VCPU is ready to receive LPIs. */
> +    if ( vcpu->arch.vgic.flags & VGIC_V3_LPIS_ENABLED )
> +        vgic_vcpu_inject_irq(vcpu, hlpi.virt_lpi);
> +
> +    rcu_unlock_domain(d);
> +}
> +
>  static int gicv3_lpi_allocate_pendtable(uint64_t *reg)
>  {
>      uint64_t val;
Cheers,

--
Julien Grall

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