KVM: arm64: vgic-v3: Enable trapping of Group-0 system registers

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.

Tested-by: Alexander Graf <agraf@suse.de>
Acked-by: David Daney <david.daney@cavium.com>
Acked-by: Christoffer Dall <cdall@linaro.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <cdall@linaro.org>

diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index 6b05d2a..c7f31a9 100644 (file)
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -417,6 +417,7 @@
 
 #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 4b2b62b..39046ee 100644 (file)
--- 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)
@@ -260,6 +261,8 @@ 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;
 }
@@ -492,7 +495,7 @@ 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);
        }