Re: [Xen-devel] [PATCH v5 16/30] ARM: vGICv3: handle disabled LPIs

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 6 Apr 2017, Andre Przywara wrote:
> If a guest disables an LPI, we do not forward this to the associated
> host LPI to avoid queueing commands to the host ITS command queue.
> So it may happen that an LPI fires nevertheless on the host. In this
> case we can bail out early, but have to save the pending state on the
> virtual side. We do this by storing the pending bit in struct
> pending_irq, which is assiociated with mapped LPIs.
> 
> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
> ---
>  xen/arch/arm/gic-v3-lpi.c | 26 +++++++++++++++++++++++++-
>  1 file changed, 25 insertions(+), 1 deletion(-)
> 
> diff --git a/xen/arch/arm/gic-v3-lpi.c b/xen/arch/arm/gic-v3-lpi.c
> index d8baebc..7d20986 100644
> --- a/xen/arch/arm/gic-v3-lpi.c
> +++ b/xen/arch/arm/gic-v3-lpi.c
> @@ -136,6 +136,22 @@ uint64_t gicv3_get_redist_address(unsigned int cpu, bool 
> use_pta)
>          return per_cpu(lpi_redist, cpu).redist_id << 16;
>  }
>  
> +static bool vgic_can_inject_lpi(struct vcpu *vcpu, uint32_t vlpi)
> +{
> +    struct pending_irq *p;
> +
> +    p = vcpu->domain->arch.vgic.handler->lpi_to_pending(vcpu->domain, vlpi);
> +    if ( !p )
> +        return false;
> +
> +    if ( test_bit(GIC_IRQ_GUEST_ENABLED, &p->status) )
> +        return true;
> +
> +    set_bit(GIC_IRQ_GUEST_LPI_PENDING, &p->status);

See alpine.DEB.2.10.1701051422020.2866@sstabellini-ThinkPad-X260


> +    return false;
> +}
> +
>  /*
>   * Handle incoming LPIs, which are a bit special, because they are 
> potentially
>   * numerous and also only get injected into guests. Treat them specially 
> here,
> @@ -187,7 +203,15 @@ void gicv3_do_LPI(unsigned int lpi)
>  
>      /* 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);
> +    {
> +        /*
> +         * We keep all host LPIs enabled, so check if it's disabled on the
> +         * guest side and just record this LPI in the virtual pending table
> +         * in this case. The guest picks it up once it gets enabled again.
> +         */
> +        if ( vgic_can_inject_lpi(vcpu, hlpi.virt_lpi) )
> +            vgic_vcpu_inject_irq(vcpu, hlpi.virt_lpi);
> +    }
>  
>      rcu_unlock_domain(d);
>  }
> -- 
> 2.8.2
> 

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel