KVM: arm64: Make AMU sysreg UNDEF if FEAT_AMU is not advertised to the guest

No AMU? No AMU! IF we see an AMU-related trap, let's turn it into
an UNDEF!

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20240214131827.2856277-24-maz@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
index da9db99c77e7c607c0c807c7a1cdeb6470bdc11b..38ed47bd29db81ca8f7cbad72e47ad44e43df0d6 100644 (file)
--- a/arch/arm64/kvm/sys_regs.c
+++ b/arch/arm64/kvm/sys_regs.c
@@ -3998,6 +3998,10 @@ void kvm_init_sysreg(struct kvm_vcpu *vcpu)
                kvm->arch.fgu[HFGxTR_GROUP] |= (HFGxTR_EL2_nPIRE0_EL1 |
                                                HFGxTR_EL2_nPIR_EL1);
 
+       if (!kvm_has_feat(kvm, ID_AA64PFR0_EL1, AMU, IMP))
+               kvm->arch.fgu[HAFGRTR_GROUP] |= ~(HAFGRTR_EL2_RES0 |
+                                                 HAFGRTR_EL2_RES1);
+
        set_bit(KVM_ARCH_FLAG_FGU_INITIALIZED, &kvm->arch.flags);
 out:
        mutex_unlock(&kvm->arch.config_lock);