Subject: [PATCH v3 1/3] KVM: arm64: Print warning when cpu erratum can cause guests to deadlock

From: Rob Herring <[email-masked]>
Date: Fri, 17 Jul 2020 14:52:31 -0600

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.

Cc: Marc Zyngier <[email-masked]>
Cc: James Morse <[email-masked]>
Cc: Julien Thierry <[email-masked]>
Cc: Suzuki K Poulose <[email-masked]>
Cc: Catalin Marinas <[email-masked]>
Cc: Will Deacon <[email-masked]>
Cc: [email-masked]
Signed-off-by: Rob Herring <[email-masked]>
---
v3:
 - s/work-arounds/workarounds/

 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..9b070b5e212b 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 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) {
--
2.25.1

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