From c5997563298bc1b9da5212c15544962d4dbbe27d Mon Sep 17 00:00:00 2001
From: Marc Zyngier <marc.zyngier@arm.com>
Date: Sat, 8 Dec 2012 18:13:18 +0000
Subject: ARM: KVM: move kvm_condition_valid to emulate.c

This is really hardware emulation, and as such it better be with
its little friends.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 arch/arm/kvm/emulate.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

(limited to 'arch/arm/kvm/emulate.c')

diff --git a/arch/arm/kvm/emulate.c b/arch/arm/kvm/emulate.c
index d3094eb4ade6..04dbac6bdf4d 100644
--- a/arch/arm/kvm/emulate.c
+++ b/arch/arm/kvm/emulate.c
@@ -20,6 +20,7 @@
 #include <linux/kvm_host.h>
 #include <asm/kvm_arm.h>
 #include <asm/kvm_emulate.h>
+#include <asm/opcodes.h>
 #include <trace/events/kvm.h>
 
 #include "trace.h"
@@ -176,6 +177,50 @@ int kvm_handle_wfi(struct kvm_vcpu *vcpu, struct kvm_run *run)
 	return 1;
 }
 
+/*
+ * A conditional instruction is allowed to trap, even though it
+ * wouldn't be executed.  So let's re-implement the hardware, in
+ * software!
+ */
+bool kvm_condition_valid(struct kvm_vcpu *vcpu)
+{
+	unsigned long cpsr, cond, insn;
+
+	/*
+	 * Exception Code 0 can only happen if we set HCR.TGE to 1, to
+	 * catch undefined instructions, and then we won't get past
+	 * the arm_exit_handlers test anyway.
+	 */
+	BUG_ON(!kvm_vcpu_trap_get_class(vcpu));
+
+	/* Top two bits non-zero?  Unconditional. */
+	if (kvm_vcpu_get_hsr(vcpu) >> 30)
+		return true;
+
+	cpsr = *vcpu_cpsr(vcpu);
+
+	/* Is condition field valid? */
+	if ((kvm_vcpu_get_hsr(vcpu) & HSR_CV) >> HSR_CV_SHIFT)
+		cond = (kvm_vcpu_get_hsr(vcpu) & HSR_COND) >> HSR_COND_SHIFT;
+	else {
+		/* This can happen in Thumb mode: examine IT state. */
+		unsigned long it;
+
+		it = ((cpsr >> 8) & 0xFC) | ((cpsr >> 25) & 0x3);
+
+		/* it == 0 => unconditional. */
+		if (it == 0)
+			return true;
+
+		/* The cond for this insn works out as the top 4 bits. */
+		cond = (it >> 4);
+	}
+
+	/* Shift makes it look like an ARM-mode instruction */
+	insn = cond << 28;
+	return arm_check_condition(insn, cpsr) != ARM_OPCODE_CONDTEST_FAIL;
+}
+
 /**
  * adjust_itstate - adjust ITSTATE when emulating instructions in IT-block
  * @vcpu:	The VCPU pointer
-- 
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