[PATCH 22/31] KVM: arm64: vgic-v3: Enable trapping of Group-0 system registers

Marc Zyngier
2017-05-03T10:43:47Z

In order to be able to trap Group-0 GICv3 system registers, we need to
set ICH_HCR_EL2.TALL0 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/vgic/vgic-v3.c | 5 ++++-
2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index a1739843343e..7fef09bcf7b1 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_TALL0 (1 << 11)
#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/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 71ecf448ca49..812f179a6931 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -21,6 +21,7 @@

#include "vgic.h"

+static bool group0_trap;
static bool group1_trap;

void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
@@ -241,6 +242,8 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu)

/* Get the show on the road... */
vgic_v3->vgic_hcr = ICH_HCR_EN;
+ if (group0_trap)
+ vgic_v3->vgic_hcr |= ICH_HCR_TALL0;
if (group1_trap)
vgic_v3->vgic_hcr |= ICH_HCR_TALL1;
}
@@ -381,7 +384,7 @@ 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) {
+ if (group0_trap || group1_trap) {
kvm_info("GICv3 sysreg trapping enabled (reduced performance)\n");
static_branch_enable(&vgic_v3_cpuif_trap);
}
--
2.11.0