From 2cbc139861ad6d8c94265f82e27ba9764fbc6579 Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier@arm.com>
Date: Fri, 9 Jun 2017 12:49:53 +0100
Subject: [PATCH 171/174] KVM: arm64: Enable GICv3 common sysreg trapping via
 command-line
Patch-mainline: Submitted, https://www.spinics.net/lists/arm-kernel/msg587082.html
References: bsc#1031492

Now that we're able to safely handle common sysreg access, let's
give the user the opportunity to enable it by passing a specific
command-line option (vgic_v3.common_trap).

Tested-by: Alexander Graf <agraf@suse.de>
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Alexander Graf <agraf@suse.de>

---
 include/linux/irqchip/arm-gic-v3.h |  1 +
 virt/kvm/arm/vgic/vgic-v3.c        | 11 ++++++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index f5b3273..06a42a2 100644
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -420,6 +420,7 @@
 
 #define ICH_HCR_EN			(1 << 0)
 #define ICH_HCR_UIE			(1 << 1)
+#define ICH_HCR_TC			(1 << 10)
 #define ICH_HCR_TALL0			(1 << 11)
 #define ICH_HCR_TALL1			(1 << 12)
 #define ICH_HCR_EOIcount_SHIFT		27
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 35c00ef..91cf8b4 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -23,6 +23,7 @@
 
 static bool group0_trap;
 static bool group1_trap;
+static bool common_trap;
 
 void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
 {
@@ -265,6 +266,8 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu)
 		vgic_v3->vgic_hcr |= ICH_HCR_TALL0;
 	if (group1_trap)
 		vgic_v3->vgic_hcr |= ICH_HCR_TALL1;
+	if (common_trap)
+		vgic_v3->vgic_hcr |= ICH_HCR_TC;
 }
 
 int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq)
@@ -450,6 +453,12 @@ static int __init early_group1_trap_cfg(char *buf)
 }
 early_param("kvm-arm.vgic_v3_group1_trap", early_group1_trap_cfg);
 
+static int __init early_common_trap_cfg(char *buf)
+{
+	return strtobool(buf, &common_trap);
+}
+early_param("kvm-arm.vgic_v3_common_trap", early_common_trap_cfg);
+
 /**
  * vgic_v3_probe - probe for a GICv3 compatible interrupt controller in DT
  * @node:	pointer to the DT node
@@ -508,7 +517,7 @@ int vgic_v3_probe(const struct gic_kvm_info *info)
 	}
 #endif
 
-	if (group0_trap || group1_trap) {
+	if (group0_trap || group1_trap || common_trap) {
 		kvm_info("GICv3 sysreg trapping enabled (reduced performance)\n");
 		static_branch_enable(&vgic_v3_cpuif_trap);
 	}
-- 
1.8.5.6