From: Marc Zyngier <marc.zyngier@arm.com>
Date: Fri, 9 Jun 2017 11:49:41 +0000 (+0100)
Subject: KVM: arm64: Enable GICv3 Group-1 sysreg trapping via command-line
X-Git-Tag: Ubuntu-4.10.0-33.37~22
X-Git-Url: https://git.proxmox.com/?p=mirror_ubuntu-zesty-kernel.git;a=commitdiff_plain;h=243f60e037544fb280faf950a7f34ab2d8f47b2d

KVM: arm64: Enable GICv3 Group-1 sysreg trapping via command-line

BugLink: https://bugs.launchpad.net/bugs/1673564

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@suse.de>
Acked-by: David Daney <david.daney@cavium.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Christoffer Dall <cdall@linaro.org>
(cherry picked from commit 182936eee7e6b1956881b51bc534a541dc71a101)
Signed-off-by: dann frazier <dann.frazier@canonical.com>
Acked-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>
---

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 48608730bc4f..0a1cf759bb71 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1800,6 +1800,10 @@
 			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 1be077a866b7..6fd6cbd70b8c 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -311,6 +311,12 @@ out:
 
 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
@@ -361,6 +367,11 @@ 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;