[PATCH v2 1/3] KVM: arm64: Print warning when cpu erratum can cause guests to deadlock

[Rob Herring]

If guests don't have certain CPU erratum work-arounds 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.

Cc: Marc Zyngier <maz at kernel.org>
Cc: James Morse <james.morse at arm.com>
Cc: Julien Thierry <julien.thierry.kdev at gmail.com>
Cc: Suzuki K Poulose <suzuki.poulose at arm.com>
Cc: Catalin Marinas <catalin.marinas at arm.com>
Cc: Will Deacon <will at kernel.org>
Cc: kvmarm at lists.cs.columbia.edu
Signed-off-by: Rob Herring <robh at kernel.org>
---
 arch/arm64/kvm/arm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 90cb90561446..e2f50fa4d825 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -1653,6 +1653,10 @@ int kvm_arch_init(void *opaque)
 		return -ENODEV;
 	}
 
+	if (cpus_have_const_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE))
+		kvm_info("Guests without required CPU erratum work-arounds 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) {
-- 
2.25.1