On Thu, Jun 01, 2017 at 11:21:03AM +0100, Marc Zyngier wrote:
> In order to be able to trap Group-1 GICv3 system registers, we need to
> set ICH_HCR_EL2.TALL1 before entering the guest. This is conditionally
> done after having restored the guest's state, and cleared on exit.
> 
> Signed-off-by: Marc Zyngier <[email protected]>

Acked-by: Christoffer Dall <[email protected]>

> ---
>  include/linux/irqchip/arm-gic-v3.h | 1 +
>  virt/kvm/arm/hyp/vgic-v3-sr.c      | 7 +++++++
>  virt/kvm/arm/vgic/vgic-v3.c        | 4 ++++
>  3 files changed, 12 insertions(+)
> 
> diff --git a/include/linux/irqchip/arm-gic-v3.h 
> b/include/linux/irqchip/arm-gic-v3.h
> index e50ce5d416a3..03b5a28bb2d0 100644
> --- a/include/linux/irqchip/arm-gic-v3.h
> +++ b/include/linux/irqchip/arm-gic-v3.h
> @@ -417,6 +417,7 @@
>  
>  #define ICH_HCR_EN                   (1 << 0)
>  #define ICH_HCR_UIE                  (1 << 1)
> +#define ICH_HCR_TALL1                        (1 << 12)
>  #define ICH_HCR_EOIcount_SHIFT               27
>  #define ICH_HCR_EOIcount_MASK                (0x1f << ICH_HCR_EOIcount_SHIFT)
>  
> diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
> index f0bc711db258..8973bad35748 100644
> --- a/virt/kvm/arm/hyp/vgic-v3-sr.c
> +++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
> @@ -258,6 +258,9 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu 
> *vcpu)
>                       cpu_if->vgic_ap1r[0] = __vgic_v3_read_ap1rn(0);
>               }
>       } else {
> +             if (static_branch_unlikely(&vgic_v3_cpuif_trap))
> +                     write_gicreg(0, ICH_HCR_EL2);
> +
>               cpu_if->vgic_elrsr = 0xffff;
>               cpu_if->vgic_ap0r[0] = 0;
>               cpu_if->vgic_ap0r[1] = 0;
> @@ -330,6 +333,10 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu 
> *vcpu)
>  
>               for (i = 0; i < used_lrs; i++)
>                       __gic_v3_set_lr(cpu_if->vgic_lr[i], i);
> +     } else {
> +             /* Always write ICH_HCR_EL2 to enable trapping */
> +             if (static_branch_unlikely(&vgic_v3_cpuif_trap))
> +                     write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2);
>       }
>  
>       /*
> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> index 88d9bd9bf468..fbd678bc046d 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -21,6 +21,8 @@
>  
>  #include "vgic.h"
>  
> +static bool group1_trap;
> +
>  void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
>  {
>       struct vgic_v3_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v3;
> @@ -239,6 +241,8 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu)
>  
>       /* Get the show on the road... */
>       vgic_v3->vgic_hcr = ICH_HCR_EN;
> +     if (group1_trap)
> +             vgic_v3->vgic_hcr |= ICH_HCR_TALL1;
>  }
>  
>  int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq)
> -- 
> 2.11.0
> 
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