[PATCH 30/31] KVM: arm64: Enable GICv3 common sysreg trapping via command-line

Marc Zyngier
2017-05-03T10:44:00Z

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).

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
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 7fef09bcf7b1..2692217ac667 100644
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -403,6 +403,7 @@

#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 445e86c8b00c..717219ab58a2 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)
{
@@ -246,6 +247,8 @@ 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;
}

/* check for overlapping regions and for regions crossing the end of memory */
@@ -339,6 +342,12 @@ static int __init early_group1_trap_cfg(char *buf)
}
early_param("vgic_v3.group1_trap", early_group1_trap_cfg);

+static int __init early_common_trap_cfg(char *buf)
+{
+ return strtobool(buf, &common_trap);
+}
+early_param("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
@@ -397,7 +406,7 @@ 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);
}
--
2.11.0