target-arm: Add computation of starting level for S2 PTW

The starting level for S2 pagetable walks is computed
differently from the S1 starting level. Implement the S2
variant.

Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
Message-id: 1445864527-14520-8-git-send-email-edgar.iglesias@gmail.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 25 insertions, 0 deletions

diff --git a/target-arm/internals.h b/target-arm/internals.h
index 36a56aadb0..8bd37eba65 100644
--- a/target-arm/internals.h
+++ b/target-arm/internals.h
@@ -152,6 +152,31 @@ static inline void update_spsel(CPUARMState *env, uint32_t imm)
     aarch64_restore_sp(env, cur_el);
 }
 
+/*
+ * arm_pamax
+ * @cpu: ARMCPU
+ *
+ * Returns the implementation defined bit-width of physical addresses.
+ * The ARMv8 reference manuals refer to this as PAMax().
+ */
+static inline unsigned int arm_pamax(ARMCPU *cpu)
+{
+    static const unsigned int pamax_map[] = {
+        [0] = 32,
+        [1] = 36,
+        [2] = 40,
+        [3] = 42,
+        [4] = 44,
+        [5] = 48,
+    };
+    unsigned int parange = extract32(cpu->id_aa64mmfr0, 0, 4);
+
+    /* id_aa64mmfr0 is a read-only register so values outside of the
+     * supported mappings can be considered an implementation error.  */
+    assert(parange < ARRAY_SIZE(pamax_map));
+    return pamax_map[parange];
+}
+
 /* Return true if extended addresses are enabled.
  * This is always the case if our translation regime is 64 bit,
  * but depends on TTBCR.EAE for 32 bit.