On Fri, Jun 09, 2017 at 12:49:41PM +0100, Marc Zyngier wrote:
> Now that we're able to safely handle Group-1 sysreg access, let's
> give the user the opportunity to enable it by passing a specific
> command-line option (vgic_v3.group1_trap).
>
> Tested-by: Alexander Graf <agraf@xxxxxxx>
> Acked-by: David Daney <david.daney@xxxxxxxxxx>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Acked-by: Christoffer Dall <cdall@xxxxxxxxxx>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 4 ++++
> virt/kvm/arm/vgic/vgic-v3.c | 11 +++++++++++
> 2 files changed, 15 insertions(+)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 15f79c27748d..42fe395be6c8 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1829,6 +1829,10 @@
> for all guests.
> Default is 1 (enabled) if in 64-bit or 32-bit PAE mode.
>
> + kvm-arm.vgic_v3_group1_trap=
> + [KVM,ARM] Trap guest accesses to GICv3 group-1
> + system registers
> +
> kvm-intel.ept= [KVM,Intel] Disable extended page tables
> (virtualized MMU) support on capable Intel chips.
> Default is 1 (enabled)
> diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
> index fbd678bc046d..df55818f095c 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -416,6 +416,12 @@ int vgic_v3_map_resources(struct kvm *kvm)
>
> DEFINE_STATIC_KEY_FALSE(vgic_v3_cpuif_trap);
>
> +static int __init early_group1_trap_cfg(char *buf)
> +{
> + return strtobool(buf, &group1_trap);
> +}
> +early_param("kvm-arm.vgic_v3_group1_trap", early_group1_trap_cfg);
> +
> /**
> * vgic_v3_probe - probe for a GICv3 compatible interrupt controller in DT
> * @node: pointer to the DT node
> @@ -467,6 +473,11 @@ 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) {
> + kvm_info("GICv3 sysreg trapping enabled (reduced performance)\n");
> + static_branch_enable(&vgic_v3_cpuif_trap);
> + }
> +
> kvm_vgic_global_state.vctrl_base = NULL;
> kvm_vgic_global_state.type = VGIC_V3;
> kvm_vgic_global_state.max_gic_vcpus = VGIC_V3_MAX_CPUS;
> --
> 2.11.0
>
