KVM: arm64: Print warning when cpu erratum can cause guests to deadlock

If guests don't have certain CPU erratum workarounds implemented, then
there is a possibility a guest can deadlock the system. IOW, only trusted
guests should be used on systems with the erratum.

This is the case for Cortex-A57 erratum 832075.

Signed-off-by: Rob Herring <[email protected]>
Acked-by: Will Deacon <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: James Morse <[email protected]>
Cc: Julien Thierry <[email protected]>
Cc: Suzuki K Poulose <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

Author: robherring

arch/arm64/kvm/arm.c

@@ -1640,6 +1640,10 @@ int kvm_arch_init(void *opaque)
 		return -ENODEV;
 	}
 
+	if (cpus_have_final_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE))
+		kvm_info("Guests without required CPU erratum workarounds can deadlock system!\n" \
+			 "Only trusted guests should be used on this system.\n");
+
 	for_each_online_cpu(cpu) {
 		smp_call_function_single(cpu, check_kvm_target_cpu, &ret, 1);
 		if (ret < 0) {