[3/3] target/arm: Support reading ZA[] from gdbstub

diff --git a/target/arm/cpu.h b/target/arm/cpu.h
index 6e97a256fb..9971280577 100644
--- a/target/arm/cpu.h
+++ b/target/arm/cpu.h
@@ -869,6 +869,7 @@  struct ArchCPU {
 
     DynamicGDBXMLInfo dyn_sysreg_xml;
     DynamicGDBXMLInfo dyn_svereg_xml;
+    DynamicGDBXMLInfo dyn_zareg_xml;
     DynamicGDBXMLInfo dyn_m_systemreg_xml;
     DynamicGDBXMLInfo dyn_m_secextreg_xml;
 
diff --git a/target/arm/internals.h b/target/arm/internals.h
index a03748aa10..a27e5b3f28 100644
--- a/target/arm/internals.h
+++ b/target/arm/internals.h
@@ -1343,12 +1343,15 @@  static inline uint64_t pmu_counter_mask(CPUARMState *env)
 
 #ifdef TARGET_AARCH64
 int arm_gen_dynamic_svereg_xml(CPUState *cpu, int base_reg);
+int arm_gen_dynamic_zareg_xml(CPUState *cpu, int base_reg);
 int aarch64_gdb_get_sve_reg(CPUARMState *env, GByteArray *buf, int reg);
 int aarch64_gdb_set_sve_reg(CPUARMState *env, uint8_t *buf, int reg);
 int aarch64_gdb_get_fpu_reg(CPUARMState *env, GByteArray *buf, int reg);
 int aarch64_gdb_set_fpu_reg(CPUARMState *env, uint8_t *buf, int reg);
 int aarch64_gdb_get_pauth_reg(CPUARMState *env, GByteArray *buf, int reg);
 int aarch64_gdb_set_pauth_reg(CPUARMState *env, uint8_t *buf, int reg);
+int aarch64_gdb_get_za_reg(CPUARMState *env, GByteArray *buf, int reg);
+int aarch64_gdb_set_za_reg(CPUARMState *env, uint8_t *buf, int reg);
 void arm_cpu_sve_finalize(ARMCPU *cpu, Error **errp);
 void arm_cpu_sme_finalize(ARMCPU *cpu, Error **errp);
 void arm_cpu_pauth_finalize(ARMCPU *cpu, Error **errp);
diff --git a/target/arm/gdbstub.c b/target/arm/gdbstub.c
index 3f799f5d05..60a9ade732 100644
--- a/target/arm/gdbstub.c
+++ b/target/arm/gdbstub.c
@@ -488,6 +488,8 @@  const char *arm_gdb_get_dynamic_xml(CPUState *cs, const char *xmlname)
         return cpu->dyn_sysreg_xml.desc;
     } else if (strcmp(xmlname, "sve-registers.xml") == 0) {
         return cpu->dyn_svereg_xml.desc;
+    } else if (strcmp(xmlname, "za-registers.xml") == 0) {
+        return cpu->dyn_zareg_xml.desc;
     } else if (strcmp(xmlname, "arm-m-system.xml") == 0) {
         return cpu->dyn_m_systemreg_xml.desc;
 #ifndef CONFIG_USER_ONLY
@@ -524,6 +526,12 @@  void arm_cpu_register_gdb_regs_for_features(ARMCPU *cpu)
                                      aarch64_gdb_set_pauth_reg,
                                      4, "aarch64-pauth.xml", 0);
         }
+        if (cpu_isar_feature(aa64_sme, cpu)) {
+            int nreg = arm_gen_dynamic_zareg_xml(cs, cs->gdb_num_regs);
+            gdb_register_coprocessor(cs, aarch64_gdb_get_za_reg,
+                                     aarch64_gdb_set_za_reg, nreg,
+                                     "za-registers.xml", 0);
+        }
 #endif
     } else {
         if (arm_feature(env, ARM_FEATURE_NEON)) {
diff --git a/target/arm/gdbstub64.c b/target/arm/gdbstub64.c
index 3bee892fb7..9210d12c4e 100644
--- a/target/arm/gdbstub64.c
+++ b/target/arm/gdbstub64.c
@@ -244,6 +244,61 @@  int aarch64_gdb_set_pauth_reg(CPUARMState *env, uint8_t *buf, int reg)
     return 0;
 }
 
+static int max_svq(ARMCPU *cpu)
+{
+    return 32 - clz32(cpu->sme_vq.map);
+}
+
+int aarch64_gdb_get_za_reg(CPUARMState *env, GByteArray *buf, int reg)
+{
+    ARMCPU *cpu = env_archcpu(env);
+    int max_vq = max_svq(cpu);
+    int cur_vq = EX_TBFLAG_A64(env->hflags, SVL) + 1;
+    int i;
+
+    if (reg >= max_vq * 16) {
+        return 0;
+    }
+
+    /* If ZA is unset, or reg out of range, the contents are zero. */
+    if (FIELD_EX64(env->svcr, SVCR, ZA) && reg < cur_vq * 16) {
+        for (i = 0; i < cur_vq; i++) {
+            gdb_get_reg128(buf, env->zarray[reg].d[i * 2 + 1],
+                           env->zarray[reg].d[i * 2]);
+        }
+    } else {
+        cur_vq = 0;
+    }
+
+    for (i = cur_vq; i < max_vq; i++) {
+        gdb_get_reg128(buf, 0, 0);
+    }
+
+    return max_vq * 16;
+}
+
+int aarch64_gdb_set_za_reg(CPUARMState *env, uint8_t *buf, int reg)
+{
+    ARMCPU *cpu = env_archcpu(env);
+    uint64_t *p = (uint64_t *) buf;
+    int max_vq = max_svq(cpu);
+    int cur_vq = EX_TBFLAG_A64(env->hflags, SVL) + 1;
+    int i;
+
+    if (reg >= max_vq * 16) {
+        return 0;
+    }
+
+    /* If ZA is unset, or reg out of range, the contents are zero. */
+    if (FIELD_EX64(env->svcr, SVCR, ZA) && reg < cur_vq * 16) {
+        for (i = 0; i < cur_vq; i++) {
+            env->zarray[reg].d[i * 2 + 1] = *p++;
+            env->zarray[reg].d[i * 2 + 0] = *p++;
+        }
+    }
+    return max_vq * 16;
+}
+
 static void output_vector_union_type(GString *s, int reg_width,
                                      const char *name)
 {
@@ -376,3 +431,36 @@  int arm_gen_dynamic_svereg_xml(CPUState *cs, int orig_base_reg)
     info->num = base_reg - orig_base_reg;
     return info->num;
 }
+
+/*
+ * Generate the xml for SME, with matrix size set to the maximum
+ * for the cpu.  Returns the number of registers generated.
+ */
+int arm_gen_dynamic_zareg_xml(CPUState *cs, int base_reg)
+{
+    ARMCPU *cpu = ARM_CPU(cs);
+    GString *s = g_string_new(NULL);
+    int vq = max_svq(cpu);
+    int row_count = vq * 16;
+    int row_width = vq * 128;
+    int i;
+
+    g_string_printf(s, "<?xml version=\"1.0\"?>");
+    g_string_append_printf(s, "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">");
+    g_string_append_printf(s, "<feature name=\"org.gnu.qemu.aarch64.za\">");
+
+    output_vector_union_type(s, row_width, "zav");
+
+    for (i = 0; i < row_count; i++) {
+        g_string_append_printf(s,
+                               "<reg name=\"za%d\" bitsize=\"%d\""
+                               " regnum=\"%d\" type=\"zav\"/>",
+                               i, row_width, base_reg + i);
+    }
+
+    g_string_append_printf(s, "</feature>");
+
+    cpu->dyn_zareg_xml.num = row_count;
+    cpu->dyn_zareg_xml.desc = g_string_free(s, false);
+    return row_count;
+}