target/arm: Don't implement *32_EL2 registers when EL1 is AArch64 only

The system registers DBGVCR32_EL2, FPEXC32_EL2, DACR32_EL2 and
IFSR32_EL2 are present only to allow an AArch64 EL2 or EL3 to read
and write the contents of an AArch32-only system register.  The
architecture requires that they are present only when EL1 can be
AArch32, but we implement them unconditionally.  This was OK when all
our CPUs supported AArch32 EL1, but we have quite a lot of CPU models
now which only support AArch64 at EL1:
 a64fx
 cortex-a76
 cortex-a710
 neoverse-n1
 neoverse-n2
 neoverse-v1

Only define these registers for CPUs which allow AArch32 EL1.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20231121144605.3980419-1-peter.maydell@linaro.org

diff --git a/target/arm/debug_helper.c b/target/arm/debug_helper.c
index cbfba532f5046f7f2022598d9766392c3040cbf0..83d2619080f1313bc832bdb390fa7c6b9c937322 100644 (file)
--- a/target/arm/debug_helper.c
+++ b/target/arm/debug_helper.c
@@ -1026,14 +1026,6 @@ static const ARMCPRegInfo debug_cp_reginfo[] = {
       .cp = 14, .opc1 = 0, .crn = 0, .crm = 7, .opc2 = 0,
       .access = PL1_RW, .accessfn = access_tda,
       .type = ARM_CP_NOP },
-    /*
-     * Dummy DBGVCR32_EL2 (which is only for a 64-bit hypervisor
-     * to save and restore a 32-bit guest's DBGVCR)
-     */
-    { .name = "DBGVCR32_EL2", .state = ARM_CP_STATE_AA64,
-      .opc0 = 2, .opc1 = 4, .crn = 0, .crm = 7, .opc2 = 0,
-      .access = PL2_RW, .accessfn = access_tda,
-      .type = ARM_CP_NOP | ARM_CP_EL3_NO_EL2_KEEP },
     /*
      * Dummy MDCCINT_EL1, since we don't implement the Debug Communications
      * Channel but Linux may try to access this register. The 32-bit
@@ -1062,6 +1054,18 @@ static const ARMCPRegInfo debug_cp_reginfo[] = {
       .fieldoffset = offsetof(CPUARMState, cp15.dbgclaim) },
 };
 
+/* These are present only when EL1 supports AArch32 */
+static const ARMCPRegInfo debug_aa32_el1_reginfo[] = {
+    /*
+     * Dummy DBGVCR32_EL2 (which is only for a 64-bit hypervisor
+     * to save and restore a 32-bit guest's DBGVCR)
+     */
+    { .name = "DBGVCR32_EL2", .state = ARM_CP_STATE_AA64,
+      .opc0 = 2, .opc1 = 4, .crn = 0, .crm = 7, .opc2 = 0,
+      .access = PL2_RW, .accessfn = access_tda,
+      .type = ARM_CP_NOP | ARM_CP_EL3_NO_EL2_KEEP },
+};
+
 static const ARMCPRegInfo debug_lpae_cp_reginfo[] = {
     /* 64 bit access versions of the (dummy) debug registers */
     { .name = "DBGDRAR", .cp = 14, .crm = 1, .opc1 = 0,
@@ -1207,6 +1211,9 @@ void define_debug_regs(ARMCPU *cpu)
     assert(ctx_cmps <= brps);
 
     define_arm_cp_regs(cpu, debug_cp_reginfo);
+    if (cpu_isar_feature(aa64_aa32_el1, cpu)) {
+        define_arm_cp_regs(cpu, debug_aa32_el1_reginfo);
+    }
 
     if (arm_feature(&cpu->env, ARM_FEATURE_LPAE)) {
         define_arm_cp_regs(cpu, debug_lpae_cp_reginfo);

diff --git a/target/arm/helper.c b/target/arm/helper.c
index 2746d3fdac884ab96a7aa07e9ed6d62195cf7630..39830c7f948c50d1a6e074aa46ae7ca108d1ef20 100644 (file)
--- a/target/arm/helper.c
+++ b/target/arm/helper.c
@@ -5698,20 +5698,6 @@ static const ARMCPRegInfo v8_cp_reginfo[] = {
       .opc0 = 3, .opc1 = 0, .crn = 4, .crm = 2, .opc2 = 0,
       .type = ARM_CP_NO_RAW,
       .access = PL1_RW, .readfn = spsel_read, .writefn = spsel_write },
-    { .name = "FPEXC32_EL2", .state = ARM_CP_STATE_AA64,
-      .opc0 = 3, .opc1 = 4, .crn = 5, .crm = 3, .opc2 = 0,
-      .access = PL2_RW,
-      .type = ARM_CP_ALIAS | ARM_CP_FPU | ARM_CP_EL3_NO_EL2_KEEP,
-      .fieldoffset = offsetof(CPUARMState, vfp.xregs[ARM_VFP_FPEXC]) },
-    { .name = "DACR32_EL2", .state = ARM_CP_STATE_AA64,
-      .opc0 = 3, .opc1 = 4, .crn = 3, .crm = 0, .opc2 = 0,
-      .access = PL2_RW, .resetvalue = 0, .type = ARM_CP_EL3_NO_EL2_KEEP,
-      .writefn = dacr_write, .raw_writefn = raw_write,
-      .fieldoffset = offsetof(CPUARMState, cp15.dacr32_el2) },
-    { .name = "IFSR32_EL2", .state = ARM_CP_STATE_AA64,
-      .opc0 = 3, .opc1 = 4, .crn = 5, .crm = 0, .opc2 = 1,
-      .access = PL2_RW, .resetvalue = 0, .type = ARM_CP_EL3_NO_EL2_KEEP,
-      .fieldoffset = offsetof(CPUARMState, cp15.ifsr32_el2) },
     { .name = "SPSR_IRQ", .state = ARM_CP_STATE_AA64,
       .type = ARM_CP_ALIAS,
       .opc0 = 3, .opc1 = 4, .crn = 4, .crm = 3, .opc2 = 0,
@@ -5746,6 +5732,24 @@ static const ARMCPRegInfo v8_cp_reginfo[] = {
       .fieldoffset = offsetoflow32(CPUARMState, cp15.mdcr_el3) },
 };
 
+/* These are present only when EL1 supports AArch32 */
+static const ARMCPRegInfo v8_aa32_el1_reginfo[] = {
+    { .name = "FPEXC32_EL2", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 4, .crn = 5, .crm = 3, .opc2 = 0,
+      .access = PL2_RW,
+      .type = ARM_CP_ALIAS | ARM_CP_FPU | ARM_CP_EL3_NO_EL2_KEEP,
+      .fieldoffset = offsetof(CPUARMState, vfp.xregs[ARM_VFP_FPEXC]) },
+    { .name = "DACR32_EL2", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 4, .crn = 3, .crm = 0, .opc2 = 0,
+      .access = PL2_RW, .resetvalue = 0, .type = ARM_CP_EL3_NO_EL2_KEEP,
+      .writefn = dacr_write, .raw_writefn = raw_write,
+      .fieldoffset = offsetof(CPUARMState, cp15.dacr32_el2) },
+    { .name = "IFSR32_EL2", .state = ARM_CP_STATE_AA64,
+      .opc0 = 3, .opc1 = 4, .crn = 5, .crm = 0, .opc2 = 1,
+      .access = PL2_RW, .resetvalue = 0, .type = ARM_CP_EL3_NO_EL2_KEEP,
+      .fieldoffset = offsetof(CPUARMState, cp15.ifsr32_el2) },
+};
+
 static void do_hcr_write(CPUARMState *env, uint64_t value, uint64_t valid_mask)
 {
     ARMCPU *cpu = env_archcpu(env);
@@ -8716,6 +8720,9 @@ void register_cp_regs_for_features(ARMCPU *cpu)
         }
         define_arm_cp_regs(cpu, v8_idregs);
         define_arm_cp_regs(cpu, v8_cp_reginfo);
+        if (cpu_isar_feature(aa64_aa32_el1, cpu)) {
+            define_arm_cp_regs(cpu, v8_aa32_el1_reginfo);
+        }
 
         for (i = 4; i < 16; i++) {
             /*