[PATCH 18/31] KVM: arm64: Enable GICv3 Group-1 sysreg trapping via command-line

Marc Zyngier
2017-05-03T10:43:42Z

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).

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
virt/kvm/arm/vgic/vgic-v3.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 547b8374fb64..71ecf448ca49 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -324,6 +324,12 @@ 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("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
@@ -375,6 +381,11 @@ 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