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 <robh@kernel.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: James Morse <james.morse@arm.com>
Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: kvmarm@lists.cs.columbia.edu
Link: https://lore.kernel.org/r/20200803193127.3012242-2-robh@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 691d21e..46dc3d7 100644 (file)
--- a/arch/arm64/kvm/arm.c
+++ b/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) {