arm64: KVM: vgic-v2: Add the GICV emulation infrastructure

In order to efficiently perform the GICV access on behalf of the
guest, we need to be able to avoid going back all the way to
the host kernel.

For this, we introduce a new hook in the world switch code,
conveniently placed just after populating the fault info.
At that point, we only have saved/restored the GP registers,
and we can quickly perform all the required checks (data abort,
translation fault, valid faulting syndrome, not an external
abort, not a PTW).

Coming back from the emulation code, we need to skip the emulated
instruction. This involves an additional bit of save/restore in
order to be able to access the guest's PC (and possibly CPSR if
this is a 32bit guest).

At this stage, no emulation code is provided.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

2 files changed, 9 insertions, 0 deletions

diff --git a/virt/kvm/arm/hyp/vgic-v2-sr.c b/virt/kvm/arm/hyp/vgic-v2-sr.c
index 7cffd9338c49..3e2a62e27eba 100644
--- a/virt/kvm/arm/hyp/vgic-v2-sr.c
+++ b/virt/kvm/arm/hyp/vgic-v2-sr.c
@@ -167,3 +167,10 @@ void __hyp_text __vgic_v2_restore_state(struct kvm_vcpu *vcpu)
         writel_relaxed(cpu_if->vgic_vmcr, base + GICH_VMCR);
         vcpu->arch.vgic_cpu.live_lrs = live_lrs;
 }
+
+#ifdef CONFIG_ARM64
+bool __hyp_text __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu)
+{
+                return false;
+}
+#endif
diff --git a/virt/kvm/arm/vgic/vgic-v2.c b/virt/kvm/arm/vgic/vgic-v2.c
index 0bf6709d1006..b8da9011889d 100644
--- a/virt/kvm/arm/vgic/vgic-v2.c
+++ b/virt/kvm/arm/vgic/vgic-v2.c
@@ -294,6 +294,8 @@ out:
         return ret;
 }
 
+DEFINE_STATIC_KEY_FALSE(vgic_v2_cpuif_trap);
+
 /**
  * vgic_v2_probe - probe for a GICv2 compatible interrupt controller in DT
  * @node:       pointer to the DT node