Re: [PATCH 22/31] KVM: arm64: vgic-v3: Enable trapping of Group-0 system registers

Auger Eric
2017-05-30T09:48:15Z

Hi,

On 03/05/2017 12:45, Marc Zyngier wrote:
> In order to be able to trap Group-0 GICv3 system registers, we need to
> set ICH_HCR_EL2.TALL0 begore entering the guest. This is conditionnaly
> done after having restored the guest's state, and cleared on exit.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

> ---
> include/linux/irqchip/arm-gic-v3.h | 1 +
> virt/kvm/arm/vgic/vgic-v3.c | 5 ++++-
> 2 files changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> index a1739843343e..7fef09bcf7b1 100644
> --- a/include/linux/irqchip/arm-gic-v3.h
> +++ b/include/linux/irqchip/arm-gic-v3.h
> @@ -403,6 +403,7 @@
>
> #define ICH_HCR_EN (1 << 0)
> #define ICH_HCR_UIE (1 << 1)
> +#define ICH_HCR_TALL0 (1 << 11)
> #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/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> index 71ecf448ca49..812f179a6931 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -21,6 +21,7 @@
>
> #include "vgic.h"
>
> +static bool group0_trap;
> static bool group1_trap;
>
> void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
> @@ -241,6 +242,8 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu)
>
> /* Get the show on the road... */
> vgic_v3->vgic_hcr = ICH_HCR_EN;
> + if (group0_trap)
> + vgic_v3->vgic_hcr |= ICH_HCR_TALL0;
Hum ok, now I get why you use the bool, sorry ;-)

Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric
> if (group1_trap)
> vgic_v3->vgic_hcr |= ICH_HCR_TALL1;
> }
> @@ -381,7 +384,7 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
> if (kvm_vgic_global_state.vcpu_base == 0)
> kvm_info("disabling GICv2 emulation\n");
>
> - if (group1_trap) {
> + if (group0_trap || group1_trap) {
> kvm_info("GICv3 sysreg trapping enabled (reduced performance)\n");
> static_branch_enable(&vgic_v3_cpuif_trap);
> }
>