target/arm: Add minimal RAS registers

Add only the system registers required to implement zero error
records.  This means that all values for ERRSELR are out of range,
which means that it and all of the indexed error record registers
need not be implemented.

Add the EL2 registers required for injecting virtual SError.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20220506180242.216785-14-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target/arm/cpu.h

@@ -525,6 +525,11 @@ typedef struct CPUArchState {
         uint64_t tfsr_el[4]; /* tfsre0_el1 is index 0.  */
         uint64_t gcr_el1;
         uint64_t rgsr_el1;
+
+        /* Minimal RAS registers */
+        uint64_t disr_el1;
+        uint64_t vdisr_el2;
+        uint64_t vsesr_el2;
     } cp15;
 
     struct {

target/arm/helper.c

@@ -5980,6 +5980,87 @@ static const ARMCPRegInfo debug_lpae_cp_reginfo[] = {
       .access = PL0_R, .type = ARM_CP_CONST|ARM_CP_64BIT, .resetvalue = 0 },
 };
 
+/*
+ * Check for traps to RAS registers, which are controlled
+ * by HCR_EL2.TERR and SCR_EL3.TERR.
+ */
+static CPAccessResult access_terr(CPUARMState *env, const ARMCPRegInfo *ri,
+                                  bool isread)
+{
+    int el = arm_current_el(env);
+
+    if (el < 2 && (arm_hcr_el2_eff(env) & HCR_TERR)) {
+        return CP_ACCESS_TRAP_EL2;
+    }
+    if (el < 3 && (env->cp15.scr_el3 & SCR_TERR)) {
+        return CP_ACCESS_TRAP_EL3;
+    }
+    return CP_ACCESS_OK;
+}
+
+static uint64_t disr_read(CPUARMState *env, const ARMCPRegInfo *ri)
+{
+    int el = arm_current_el(env);
+
+    if (el < 2 && (arm_hcr_el2_eff(env) & HCR_AMO)) {
+        return env->cp15.vdisr_el2;
+    }
+    if (el < 3 && (env->cp15.scr_el3 & SCR_EA)) {
+        return 0; /* RAZ/WI */
+    }
+    return env->cp15.disr_el1;
+}
+
+static void disr_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t val)
+{
+    int el = arm_current_el(env);
+
+    if (el < 2 && (arm_hcr_el2_eff(env) & HCR_AMO)) {
+        env->cp15.vdisr_el2 = val;
+        return;
+    }
+    if (el < 3 && (env->cp15.scr_el3 & SCR_EA)) {
+        return; /* RAZ/WI */
+    }
+    env->cp15.disr_el1 = val;
+}
+
+/*
+ * Minimal RAS implementation with no Error Records.
+ * Which means that all of the Error Record registers:
+ *   ERXADDR_EL1
+ *   ERXCTLR_EL1
+ *   ERXFR_EL1
+ *   ERXMISC0_EL1
+ *   ERXMISC1_EL1
+ *   ERXMISC2_EL1
+ *   ERXMISC3_EL1
+ *   ERXPFGCDN_EL1  (RASv1p1)
+ *   ERXPFGCTL_EL1  (RASv1p1)
+ *   ERXPFGF_EL1    (RASv1p1)
+ *   ERXSTATUS_EL1
+ * and
+ *   ERRSELR_EL1
+ * may generate UNDEFINED, which is the effect we get by not
+ * listing them at all.
+ */
+static const ARMCPRegInfo minimal_ras_reginfo[] = {
+    { .name = "DISR_EL1", .state = ARM_CP_STATE_BOTH,
+      .opc0 = 3, .opc1 = 0, .crn = 12, .crm = 1, .opc2 = 1,
+      .access = PL1_RW, .fieldoffset = offsetof(CPUARMState, cp15.disr_el1),
+      .readfn = disr_read, .writefn = disr_write, .raw_writefn = raw_write },
+    { .name = "ERRIDR_EL1", .state = ARM_CP_STATE_BOTH,
+      .opc0 = 3, .opc1 = 0, .crn = 5, .crm = 3, .opc2 = 0,
+      .access = PL1_R, .accessfn = access_terr,
+      .type = ARM_CP_CONST, .resetvalue = 0 },
+    { .name = "VDISR_EL2", .state = ARM_CP_STATE_BOTH,
+      .opc0 = 3, .opc1 = 4, .crn = 12, .crm = 1, .opc2 = 1,
+      .access = PL2_RW, .fieldoffset = offsetof(CPUARMState, cp15.vdisr_el2) },
+    { .name = "VSESR_EL2", .state = ARM_CP_STATE_BOTH,
+      .opc0 = 3, .opc1 = 4, .crn = 5, .crm = 2, .opc2 = 3,
+      .access = PL2_RW, .fieldoffset = offsetof(CPUARMState, cp15.vsesr_el2) },
+};
+
 /* Return the exception level to which exceptions should be taken
  * via SVEAccessTrap.  If an exception should be routed through
  * AArch64.AdvSIMDFPAccessTrap, return 0; fp_exception_el should
@@ -8217,6 +8298,9 @@ void register_cp_regs_for_features(ARMCPU *cpu)
     if (cpu_isar_feature(aa64_ssbs, cpu)) {
         define_one_arm_cp_reg(cpu, &ssbs_reginfo);
     }
+    if (cpu_isar_feature(any_ras, cpu)) {
+        define_arm_cp_regs(cpu, minimal_ras_reginfo);
+    }
 
     if (cpu_isar_feature(aa64_vh, cpu) ||
         cpu_isar_feature(aa64_debugv8p2, cpu)) {