[PATCH 17/31] KVM: arm64: vgic-v3: Enable trapping of Group-1 system registers

Marc Zyngier
2017-05-03T10:43:38Z

In order to be able to trap Group-1 GICv3 system registers, we need to
set ICH_HCR_EL2.TALL1 begore entering the guest. This is conditionnaly
done after having restored the guest's state, and cleared on exit.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
include/linux/irqchip/arm-gic-v3.h | 1 +
virt/kvm/arm/hyp/vgic-v3-sr.c | 7 +++++++
virt/kvm/arm/vgic/vgic-v3.c | 4 ++++
3 files changed, 12 insertions(+)

diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index c56d9bc2c904..a1739843343e 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_TALL1 (1 << 12)
#define ICH_HCR_EOIcount_SHIFT 27
#define ICH_HCR_EOIcount_MASK (0x1f << ICH_HCR_EOIcount_SHIFT)

diff --git a/virt/kvm/arm/hyp/vgic-v3-sr.c b/virt/kvm/arm/hyp/vgic-v3-sr.c
index a521e105ade1..a27671b1e9af 100644
--- a/virt/kvm/arm/hyp/vgic-v3-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v3-sr.c
@@ -257,6 +257,9 @@ void __hyp_text __vgic_v3_save_state(struct kvm_vcpu *vcpu)
cpu_if->vgic_ap1r[0] = __vgic_v3_read_ap1rn(0);
}
} else {
+ if (static_branch_unlikely(&vgic_v3_cpuif_trap))
+ write_gicreg(0, ICH_HCR_EL2);
+
cpu_if->vgic_elrsr = 0xffff;
cpu_if->vgic_ap0r[0] = 0;
cpu_if->vgic_ap0r[1] = 0;
@@ -329,6 +332,10 @@ void __hyp_text __vgic_v3_restore_state(struct kvm_vcpu *vcpu)

for (i = 0; i < used_lrs; i++)
__gic_v3_set_lr(cpu_if->vgic_lr[i], i);
+ } else {
+ /* Always write ICH_HCR_EL2 to enable trapping */
+ if (static_branch_unlikely(&vgic_v3_cpuif_trap))
+ write_gicreg(cpu_if->vgic_hcr, ICH_HCR_EL2);
}

/*
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 063526443781..547b8374fb64 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -21,6 +21,8 @@

#include "vgic.h"

+static bool group1_trap;
+
void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
{
struct vgic_v3_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v3;
@@ -239,6 +241,8 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu)

/* Get the show on the road... */
vgic_v3->vgic_hcr = ICH_HCR_EN;
+ if (group1_trap)
+ vgic_v3->vgic_hcr |= ICH_HCR_TALL1;
}

/* check for overlapping regions and for regions crossing the end of memory */
--
2.11.0