Hi Marc,

On 03/04/2013 10:47 PM, Marc Zyngier wrote:

Let userspace play with the guest registers.

Signed-off-by: Marc Zyngier <redacted>
---
 arch/arm64/kvm/guest.c | 240 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 240 insertions(+)
 create mode 100644 arch/arm64/kvm/guest.c

[...]

+int __attribute_const__ kvm_target_cpu(void)
+{
+	unsigned long implementor = read_cpuid_implementor();
+	unsigned long part_number = read_cpuid_part_number();
+
+	if (implementor != ARM_CPU_IMP_ARM)
+		return -EINVAL;
+
+	switch (part_number) {
+	case ARM_CPU_PART_AEM_V8:
+	case ARM_CPU_PART_FOUNDATION:
+		/* Treat the models just as an A57 for the time being */
+	case ARM_CPU_PART_CORTEX_A57:
+		return KVM_ARM_TARGET_CORTEX_A57;
+	default:
+		return -EINVAL;
+	}
+}

What is the motivation behind these checks? Why not let any ARMv8 system that
has EL2 host a virtualized Cortex A57 guest?

[...]

Thanks,
Christopher

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