[PATCH] ARM: KVM: Check the cpuid we're being asked to emulate.

["Rusty Russell" <rusty.russell@linaro.org>]

As our emulation gets more sophisticated, we need to know what CPU model
we're dealing with.  Particularly for some of the nastier workarounds.

Let's start with Cortex A-15.  We can then test the MIDR elsewhere in the
code, knowing that it's one of a finite set of allowed values.

Signed-off-by: Rusty Russell <rusty.russell@linaro.org>

diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
index c0adab0..2195bc9 100644
--- a/arch/arm/kvm/guest.c
+++ b/arch/arm/kvm/guest.c
@@ -82,6 +82,24 @@ int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
 int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
 {
 	struct kvm_vcpu_regs *vcpu_regs = &vcpu->arch.regs;
+	u32 impl, var, arch, part;
+
+	/* Check we understand what CPU we're being asked to emulate. */
+	impl = (regs->cp15.c0_midr & 0xFF000000) >> 24;
+	var = (regs->cp15.c0_midr & 0x00F00000) >> 20;
+	arch = (regs->cp15.c0_midr & 0x000F0000) >> 16;
+	part = (regs->cp15.c0_midr & 0x0000FFF0) >> 4;
+
+	switch (regs->cp15.c0_midr >> 24) {
+	case 'A': /* ARM */
+		/* Cortex-A15 */
+		if (var == 0x2 && arch == 0xF && part == 0xC0F)
+			break;
+		else
+			return -EINVAL;
+	default:
+		return -EINVAL;
+	}
 
 	memcpy(&(vcpu_regs->usr_regs[0]), regs->regs0_7, sizeof(u32) * 8);
 	memcpy(&(vcpu_regs->usr_regs[8]), regs->usr_regs8_12, sizeof(u32) * 5);