target/arm: Enable FEAT_HCX for -cpu max

This feature adds a new register, HCRX_EL2, which controls
many of the newer AArch64 features.  So far the register is
effectively RES0, because none of the new features are done.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220517054850.177016-2-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/cpu.h

@@ -362,6 +362,7 @@ typedef struct CPUArchState {
         uint32_t pmsav5_data_ap; /* PMSAv5 MPU data access permissions */
         uint32_t pmsav5_insn_ap; /* PMSAv5 MPU insn access permissions */
         uint64_t hcr_el2; /* Hypervisor configuration register */
+        uint64_t hcrx_el2; /* Extended Hypervisor configuration register */
         uint64_t scr_el3; /* Secure configuration register.  */
         union { /* Fault status registers.  */
             struct {
@@ -1545,6 +1546,19 @@ static inline void xpsr_write(CPUARMState *env, uint32_t val, uint32_t mask)
 #define HCR_TWEDEN    (1ULL << 59)
 #define HCR_TWEDEL    MAKE_64BIT_MASK(60, 4)
 
+#define HCRX_ENAS0    (1ULL << 0)
+#define HCRX_ENALS    (1ULL << 1)
+#define HCRX_ENASR    (1ULL << 2)
+#define HCRX_FNXS     (1ULL << 3)
+#define HCRX_FGTNXS   (1ULL << 4)
+#define HCRX_SMPME    (1ULL << 5)
+#define HCRX_TALLINT  (1ULL << 6)
+#define HCRX_VINMI    (1ULL << 7)
+#define HCRX_VFNMI    (1ULL << 8)
+#define HCRX_CMOW     (1ULL << 9)
+#define HCRX_MCE2     (1ULL << 10)
+#define HCRX_MSCEN    (1ULL << 11)
+
 #define HPFAR_NS      (1ULL << 63)
 
 #define SCR_NS                (1U << 0)
@@ -2312,6 +2326,7 @@ static inline bool arm_is_el2_enabled(CPUARMState *env)
  * Not included here is HCR_RW.
  */
 uint64_t arm_hcr_el2_eff(CPUARMState *env);
+uint64_t arm_hcrx_el2_eff(CPUARMState *env);
 
 /* Return true if the specified exception level is running in AArch64 state. */
 static inline bool arm_el_is_aa64(CPUARMState *env, int el)
@@ -3933,6 +3948,11 @@ static inline bool isar_feature_aa64_ats1e1(const ARMISARegisters *id)
     return FIELD_EX64(id->id_aa64mmfr1, ID_AA64MMFR1, PAN) >= 2;
 }
 
+static inline bool isar_feature_aa64_hcx(const ARMISARegisters *id)
+{
+    return FIELD_EX64(id->id_aa64mmfr1, ID_AA64MMFR1, HCX) != 0;
+}
+
 static inline bool isar_feature_aa64_uao(const ARMISARegisters *id)
 {
     return FIELD_EX64(id->id_aa64mmfr2, ID_AA64MMFR2, UAO) != 0;

target/arm/cpu64.c

@@ -934,6 +934,7 @@ static void aarch64_max_initfn(Object *obj)
     t = FIELD_DP64(t, ID_AA64MMFR1, LO, 1);       /* FEAT_LOR */
     t = FIELD_DP64(t, ID_AA64MMFR1, PAN, 2);      /* FEAT_PAN2 */
     t = FIELD_DP64(t, ID_AA64MMFR1, XNX, 1);      /* FEAT_XNX */
+    t = FIELD_DP64(t, ID_AA64MMFR1, HCX, 1);      /* FEAT_HCX */
     cpu->isar.id_aa64mmfr1 = t;
 
     t = cpu->isar.id_aa64mmfr2;

target/arm/helper.c

@@ -5288,6 +5288,52 @@ uint64_t arm_hcr_el2_eff(CPUARMState *env)
     return ret;
 }
 
+static void hcrx_write(CPUARMState *env, const ARMCPRegInfo *ri,
+                       uint64_t value)
+{
+    uint64_t valid_mask = 0;
+
+    /* No features adding bits to HCRX are implemented. */
+
+    /* Clear RES0 bits.  */
+    env->cp15.hcrx_el2 = value & valid_mask;
+}
+
+static CPAccessResult access_hxen(CPUARMState *env, const ARMCPRegInfo *ri,
+                                  bool isread)
+{
+    if (arm_current_el(env) < 3
+        && arm_feature(env, ARM_FEATURE_EL3)
+        && !(env->cp15.scr_el3 & SCR_HXEN)) {
+        return CP_ACCESS_TRAP_EL3;
+    }
+    return CP_ACCESS_OK;
+}
+
+static const ARMCPRegInfo hcrx_el2_reginfo = {
+    .name = "HCRX_EL2", .state = ARM_CP_STATE_AA64,
+    .opc0 = 3, .opc1 = 4, .crn = 1, .crm = 2, .opc2 = 2,
+    .access = PL2_RW, .writefn = hcrx_write, .accessfn = access_hxen,
+    .fieldoffset = offsetof(CPUARMState, cp15.hcrx_el2),
+};
+
+/* Return the effective value of HCRX_EL2.  */
+uint64_t arm_hcrx_el2_eff(CPUARMState *env)
+{
+    /*
+     * The bits in this register behave as 0 for all purposes other than
+     * direct reads of the register if:
+     *   - EL2 is not enabled in the current security state,
+     *   - SCR_EL3.HXEn is 0.
+     */
+    if (!arm_is_el2_enabled(env)
+        || (arm_feature(env, ARM_FEATURE_EL3)
+            && !(env->cp15.scr_el3 & SCR_HXEN))) {
+        return 0;
+    }
+    return env->cp15.hcrx_el2;
+}
+
 static void cptr_el2_write(CPUARMState *env, const ARMCPRegInfo *ri,
                            uint64_t value)
 {
@@ -8405,6 +8451,10 @@ void register_cp_regs_for_features(ARMCPU *cpu)
         define_arm_cp_regs(cpu, zcr_reginfo);
     }
 
+    if (cpu_isar_feature(aa64_hcx, cpu)) {
+        define_one_arm_cp_reg(cpu, &hcrx_el2_reginfo);
+    }
+
 #ifdef TARGET_AARCH64
     if (cpu_isar_feature(aa64_pauth, cpu)) {
         define_arm_cp_regs(cpu, pauth_reginfo);