Re: [PATCH v5 25/26] KVM: arm/arm64: GICv4: Enable VLPI support

Auger Eric
2017-11-08T08:42:52Z

Hi Marc,

On 27/10/2017 16:28, Marc Zyngier wrote:
> All it takes is the has_v4 flag to be set in gic_kvm_info
> as well as "kvm-arm.vgic_v4_enable=1" being passed on the
> command line for GICv4 to be enabled in KVM.

What did you motivate your choice of having an enable option instead of
a disable option?

Thanks

Eric
>
> Acked-by: Christoffer Dall <cdall@linaro.org>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 4 ++++
> virt/kvm/arm/vgic/vgic-v3.c | 14 ++++++++++++++
> 2 files changed, 18 insertions(+)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 05496622b4ef..93c8fff399eb 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1874,6 +1874,10 @@
> [KVM,ARM] Trap guest accesses to GICv3 common
> system registers
>
> + kvm-arm.vgic_v4_enable=
> + [KVM,ARM] Allow use of GICv4 for direct injection of
> + LPIs.
> +
> 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 96ea597db0e7..405733678c2f 100644
> --- a/virt/kvm/arm/vgic/vgic-v3.c
> +++ b/virt/kvm/arm/vgic/vgic-v3.c
> @@ -24,6 +24,7 @@
> static bool group0_trap;
> static bool group1_trap;
> static bool common_trap;
> +static bool gicv4_enable;
>
> void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
> {
> @@ -459,6 +460,12 @@ static int __init early_common_trap_cfg(char *buf)
> }
> early_param("kvm-arm.vgic_v3_common_trap", early_common_trap_cfg);
>
> +static int __init early_gicv4_enable(char *buf)
> +{
> + return strtobool(buf, &gicv4_enable);
> +}
> +early_param("kvm-arm.vgic_v4_enable", early_gicv4_enable);
> +
> /**
> * vgic_v3_probe - probe for a GICv3 compatible interrupt controller in DT
> * @node: pointer to the DT node
> @@ -478,6 +485,13 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
> kvm_vgic_global_state.can_emulate_gicv2 = false;
> kvm_vgic_global_state.ich_vtr_el2 = ich_vtr_el2;
>
> + /* GICv4 support? */
> + if (info->has_v4) {
> + kvm_vgic_global_state.has_gicv4 = gicv4_enable;
> + kvm_info("GICv4 support %sabled\n",
> + gicv4_enable ? "en" : "dis");
> + }
> +
> if (!info->vcpu.start) {
> kvm_info("GICv3: no GICV resource entry\n");
> kvm_vgic_global_state.vcpu_base = 0;
>