KVM: arm64: nv: Fail KVM init if asking for NV without GICv3

Although there is nothing in NV that is fundamentally incompatible
with the lack of GICv3, there is no HW implementation without one,
at least on the virtual side (yes, even fruits have some form of
vGICv3).

We therefore make the decision to require GICv3, which will only
affect models such as QEMU. Booting with a GICv2 or something
even more exotic while asking for NV will result in KVM being
disabled.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250225172930.1850838-17-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index abf51f6cfcafe8dfa58e2f0405d710e82734b272..a67653e2622529a99544f38c3bc1b7cecdf24ecc 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -2325,6 +2325,13 @@ static int __init init_subsystems(void)
                goto out;
        }
 
+       if (kvm_mode == KVM_MODE_NV &&
+          !(vgic_present && kvm_vgic_global_state.type == VGIC_V3)) {
+               kvm_err("NV support requires GICv3, giving up\n");
+               err = -EINVAL;
+               goto out;
+       }
+
        /*
         * Init HYP architected timer support
         */