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
qemu · Dec 19, 2023 · c36a0d5 · c36a0d5
1 parent 366bf10
commit c36a0d5
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Showing 2 changed files with 36 additions and 22 deletions.
diff --git 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
@@ -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++) {
             /*