target-arm: Convert TCG to using (index,value) list for cp migration

Convert the TCG ARM target to using an (index,value) list for migrating
coprocessors. The primary benefit of the (index,value) list is for
passing state between KVM and QEMU, but it works for TCG-to-TCG
migration as well and is a useful self-contained first step.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

target-arm/cpu-qom.h

@@ -62,6 +62,25 @@ typedef struct ARMCPU {
 
     /* Coprocessor information */
     GHashTable *cp_regs;
+    /* For marshalling (mostly coprocessor) register state between the
+     * kernel and QEMU (for KVM) and between two QEMUs (for migration),
+     * we use these arrays.
+     */
+    /* List of register indexes managed via these arrays; (full KVM style
+     * 64 bit indexes, not CPRegInfo 32 bit indexes)
+     */
+    uint64_t *cpreg_indexes;
+    /* Values of the registers (cpreg_indexes[i]'s value is cpreg_values[i]) */
+    uint64_t *cpreg_values;
+    /* Length of the indexes, values arrays */
+    int32_t cpreg_array_len;
+    /* These are used only for migration: incoming data arrives in
+     * these fields and is sanity checked in post_load before copying
+     * to the working data structures above.
+     */
+    uint64_t *cpreg_vmstate_indexes;
+    uint64_t *cpreg_vmstate_values;
+    int32_t cpreg_vmstate_array_len;
 
     /* The instance init functions for implementation-specific subclasses
      * set these fields to specify the implementation-dependent values of
@@ -116,6 +135,7 @@ extern const struct VMStateDescription vmstate_arm_cpu;
 #endif
 
 void register_cp_regs_for_features(ARMCPU *cpu);
+void init_cpreg_list(ARMCPU *cpu);
 
 void arm_cpu_do_interrupt(CPUState *cpu);
 void arm_v7m_cpu_do_interrupt(CPUState *cpu);

target-arm/cpu.c

@@ -204,6 +204,8 @@ static void arm_cpu_realizefn(DeviceState *dev, Error **errp)
     register_cp_regs_for_features(cpu);
     arm_cpu_register_gdb_regs_for_features(cpu);
 
+    init_cpreg_list(cpu);
+
     cpu_reset(CPU(cpu));
     qemu_init_vcpu(env);
 

target-arm/cpu.h

@@ -424,6 +424,43 @@ void armv7m_nvic_complete_irq(void *opaque, int irq);
     (((cp) << 16) | ((is64) << 15) | ((crn) << 11) |    \
      ((crm) << 7) | ((opc1) << 3) | (opc2))
 
+/* Note that these must line up with the KVM/ARM register
+ * ID field definitions (kvm.c will check this, but we
+ * can't just use the KVM defines here as the kvm headers
+ * are unavailable to non-KVM-specific files)
+ */
+#define CP_REG_SIZE_SHIFT 52
+#define CP_REG_SIZE_MASK       0x00f0000000000000ULL
+#define CP_REG_SIZE_U32        0x0020000000000000ULL
+#define CP_REG_SIZE_U64        0x0030000000000000ULL
+#define CP_REG_ARM             0x4000000000000000ULL
+
+/* Convert a full 64 bit KVM register ID to the truncated 32 bit
+ * version used as a key for the coprocessor register hashtable
+ */
+static inline uint32_t kvm_to_cpreg_id(uint64_t kvmid)
+{
+    uint32_t cpregid = kvmid;
+    if ((kvmid & CP_REG_SIZE_MASK) == CP_REG_SIZE_U64) {
+        cpregid |= (1 << 15);
+    }
+    return cpregid;
+}
+
+/* Convert a truncated 32 bit hashtable key into the full
+ * 64 bit KVM register ID.
+ */
+static inline uint64_t cpreg_to_kvm_id(uint32_t cpregid)
+{
+    uint64_t kvmid = cpregid & ~(1 << 15);
+    if (cpregid & (1 << 15)) {
+        kvmid |= CP_REG_SIZE_U64 | CP_REG_ARM;
+    } else {
+        kvmid |= CP_REG_SIZE_U32 | CP_REG_ARM;
+    }
+    return kvmid;
+}
+
 /* ARMCPRegInfo type field bits. If the SPECIAL bit is set this is a
  * special-behaviour cp reg and bits [15..8] indicate what behaviour
  * it has. Otherwise it is a simple cp reg, where CONST indicates that
@@ -621,6 +658,38 @@ static inline bool cp_access_ok(CPUARMState *env,
     return (ri->access >> ((arm_current_pl(env) * 2) + isread)) & 1;
 }
 
+/**
+ * write_list_to_cpustate
+ * @cpu: ARMCPU
+ *
+ * For each register listed in the ARMCPU cpreg_indexes list, write
+ * its value from the cpreg_values list into the ARMCPUState structure.
+ * This updates TCG's working data structures from KVM data or
+ * from incoming migration state.
+ *
+ * Returns: true if all register values were updated correctly,
+ * false if some register was unknown or could not be written.
+ * Note that we do not stop early on failure -- we will attempt
+ * writing all registers in the list.
+ */
+bool write_list_to_cpustate(ARMCPU *cpu);
+
+/**
+ * write_cpustate_to_list:
+ * @cpu: ARMCPU
+ *
+ * For each register listed in the ARMCPU cpreg_indexes list, write
+ * its value from the ARMCPUState structure into the cpreg_values list.
+ * This is used to copy info from TCG's working data structures into
+ * KVM or for outbound migration.
+ *
+ * Returns: true if all register values were read correctly,
+ * false if some register was unknown or could not be read.
+ * Note that we do not stop early on failure -- we will attempt
+ * reading all registers in the list.
+ */
+bool write_cpustate_to_list(ARMCPU *cpu);
+
 /* Does the core conform to the the "MicroController" profile. e.g. Cortex-M3.
    Note the M in older cores (eg. ARM7TDMI) stands for Multiply. These are
    conventional cores (ie. Application or Realtime profile).  */

target-arm/helper.c

@@ -78,6 +78,180 @@ static int raw_write(CPUARMState *env, const ARMCPRegInfo *ri,
     return 0;
 }
 
+static bool read_raw_cp_reg(CPUARMState *env, const ARMCPRegInfo *ri,
+                            uint64_t *v)
+{
+    /* Raw read of a coprocessor register (as needed for migration, etc)
+     * return true on success, false if the read is impossible for some reason.
+     */
+    if (ri->type & ARM_CP_CONST) {
+        *v = ri->resetvalue;
+    } else if (ri->raw_readfn) {
+        return (ri->raw_readfn(env, ri, v) == 0);
+    } else if (ri->readfn) {
+        return (ri->readfn(env, ri, v) == 0);
+    } else {
+        if (ri->type & ARM_CP_64BIT) {
+            *v = CPREG_FIELD64(env, ri);
+        } else {
+            *v = CPREG_FIELD32(env, ri);
+        }
+    }
+    return true;
+}
+
+static bool write_raw_cp_reg(CPUARMState *env, const ARMCPRegInfo *ri,
+                             int64_t v)
+{
+    /* Raw write of a coprocessor register (as needed for migration, etc).
+     * Return true on success, false if the write is impossible for some reason.
+     * Note that constant registers are treated as write-ignored; the
+     * caller should check for success by whether a readback gives the
+     * value written.
+     */
+    if (ri->type & ARM_CP_CONST) {
+        return true;
+    } else if (ri->raw_writefn) {
+        return (ri->raw_writefn(env, ri, v) == 0);
+    } else if (ri->writefn) {
+        return (ri->writefn(env, ri, v) == 0);
+    } else {
+        if (ri->type & ARM_CP_64BIT) {
+            CPREG_FIELD64(env, ri) = v;
+        } else {
+            CPREG_FIELD32(env, ri) = v;
+        }
+    }
+    return true;
+}
+
+bool write_cpustate_to_list(ARMCPU *cpu)
+{
+    /* Write the coprocessor state from cpu->env to the (index,value) list. */
+    int i;
+    bool ok = true;
+
+    for (i = 0; i < cpu->cpreg_array_len; i++) {
+        uint32_t regidx = kvm_to_cpreg_id(cpu->cpreg_indexes[i]);
+        const ARMCPRegInfo *ri;
+        uint64_t v;
+        ri = get_arm_cp_reginfo(cpu, regidx);
+        if (!ri) {
+            ok = false;
+            continue;
+        }
+        if (ri->type & ARM_CP_NO_MIGRATE) {
+            continue;
+        }
+        if (!read_raw_cp_reg(&cpu->env, ri, &v)) {
+            ok = false;
+            continue;
+        }
+        cpu->cpreg_values[i] = v;
+    }
+    return ok;
+}
+
+bool write_list_to_cpustate(ARMCPU *cpu)
+{
+    int i;
+    bool ok = true;
+
+    for (i = 0; i < cpu->cpreg_array_len; i++) {
+        uint32_t regidx = kvm_to_cpreg_id(cpu->cpreg_indexes[i]);
+        uint64_t v = cpu->cpreg_values[i];
+        uint64_t readback;
+        const ARMCPRegInfo *ri;
+
+        ri = get_arm_cp_reginfo(cpu, regidx);
+        if (!ri) {
+            ok = false;
+            continue;
+        }
+        if (ri->type & ARM_CP_NO_MIGRATE) {
+            continue;
+        }
+        /* Write value and confirm it reads back as written
+         * (to catch read-only registers and partially read-only
+         * registers where the incoming migration value doesn't match)
+         */
+        if (!write_raw_cp_reg(&cpu->env, ri, v) ||
+            !read_raw_cp_reg(&cpu->env, ri, &readback) ||
+            readback != v) {
+            ok = false;
+        }
+    }
+    return ok;
+}
+
+static void add_cpreg_to_list(gpointer key, gpointer opaque)
+{
+    ARMCPU *cpu = opaque;
+    uint64_t regidx;
+    const ARMCPRegInfo *ri;
+
+    regidx = *(uint32_t *)key;
+    ri = get_arm_cp_reginfo(cpu, regidx);
+
+    if (!(ri->type & ARM_CP_NO_MIGRATE)) {
+        cpu->cpreg_indexes[cpu->cpreg_array_len] = cpreg_to_kvm_id(regidx);
+        /* The value array need not be initialized at this point */
+        cpu->cpreg_array_len++;
+    }
+}
+
+static void count_cpreg(gpointer key, gpointer opaque)
+{
+    ARMCPU *cpu = opaque;
+    uint64_t regidx;
+    const ARMCPRegInfo *ri;
+
+    regidx = *(uint32_t *)key;
+    ri = get_arm_cp_reginfo(cpu, regidx);
+
+    if (!(ri->type & ARM_CP_NO_MIGRATE)) {
+        cpu->cpreg_array_len++;
+    }
+}
+
+static gint cpreg_key_compare(gconstpointer a, gconstpointer b)
+{
+    uint32_t aidx = *(uint32_t *)a;
+    uint32_t bidx = *(uint32_t *)b;
+
+    return aidx - bidx;
+}
+
+void init_cpreg_list(ARMCPU *cpu)
+{
+    /* Initialise the cpreg_tuples[] array based on the cp_regs hash.
+     * Note that we require cpreg_tuples[] to be sorted by key ID.
+     */
+    GList *keys;
+    int arraylen;
+
+    keys = g_hash_table_get_keys(cpu->cp_regs);
+    keys = g_list_sort(keys, cpreg_key_compare);
+
+    cpu->cpreg_array_len = 0;
+
+    g_list_foreach(keys, count_cpreg, cpu);
+
+    arraylen = cpu->cpreg_array_len;
+    cpu->cpreg_indexes = g_new(uint64_t, arraylen);
+    cpu->cpreg_values = g_new(uint64_t, arraylen);
+    cpu->cpreg_vmstate_indexes = g_new(uint64_t, arraylen);
+    cpu->cpreg_vmstate_values = g_new(uint64_t, arraylen);
+    cpu->cpreg_vmstate_array_len = cpu->cpreg_array_len;
+    cpu->cpreg_array_len = 0;
+
+    g_list_foreach(keys, add_cpreg_to_list, cpu);
+
+    assert(cpu->cpreg_array_len == arraylen);
+
+    g_list_free(keys);
+}
+
 static int dacr_write(CPUARMState *env, const ARMCPRegInfo *ri, uint64_t value)
 {
     env->cp15.c3 = value;

target-arm/kvm.c

@@ -23,6 +23,15 @@
 #include "cpu.h"
 #include "hw/arm/arm.h"
 
+/* Check that cpu.h's idea of coprocessor fields matches KVM's */
+#if (CP_REG_SIZE_SHIFT != KVM_REG_SIZE_SHIFT) || \
+    (CP_REG_SIZE_MASK != KVM_REG_SIZE_MASK) ||   \
+    (CP_REG_SIZE_U32 != KVM_REG_SIZE_U32) || \
+    (CP_REG_SIZE_U64 != KVM_REG_SIZE_U64) || \
+    (CP_REG_ARM != KVM_REG_ARM)
+#error mismatch between cpu.h and KVM header definitions
+#endif
+
 const KVMCapabilityInfo kvm_arch_required_capabilities[] = {
     KVM_CAP_LAST_INFO
 };

target-arm/machine.c

@@ -148,11 +148,65 @@ static const VMStateInfo vmstate_cpsr = {
     .put = put_cpsr,
 };
 
+static void cpu_pre_save(void *opaque)
+{
+    ARMCPU *cpu = opaque;
+
+    if (!write_cpustate_to_list(cpu)) {
+        /* This should never fail. */
+        abort();
+    }
+
+    cpu->cpreg_vmstate_array_len = cpu->cpreg_array_len;
+    memcpy(cpu->cpreg_vmstate_indexes, cpu->cpreg_indexes,
+           cpu->cpreg_array_len * sizeof(uint64_t));
+    memcpy(cpu->cpreg_vmstate_values, cpu->cpreg_values,
+           cpu->cpreg_array_len * sizeof(uint64_t));
+}
+
+static int cpu_post_load(void *opaque, int version_id)
+{
+    ARMCPU *cpu = opaque;
+    int i, v;
+
+    /* Update the values list from the incoming migration data.
+     * Anything in the incoming data which we don't know about is
+     * a migration failure; anything we know about but the incoming
+     * data doesn't specify retains its current (reset) value.
+     * The indexes list remains untouched -- we only inspect the
+     * incoming migration index list so we can match the values array
+     * entries with the right slots in our own values array.
+     */
+
+    for (i = 0, v = 0; i < cpu->cpreg_array_len
+             && v < cpu->cpreg_vmstate_array_len; i++) {
+        if (cpu->cpreg_vmstate_indexes[v] > cpu->cpreg_indexes[i]) {
+            /* register in our list but not incoming : skip it */
+            continue;
+        }
+        if (cpu->cpreg_vmstate_indexes[v] < cpu->cpreg_indexes[i]) {
+            /* register in their list but not ours: fail migration */
+            return -1;
+        }
+        /* matching register, copy the value over */
+        cpu->cpreg_values[i] = cpu->cpreg_vmstate_values[v];
+        v++;
+    }
+
+    if (!write_list_to_cpustate(cpu)) {
+        return -1;
+    }
+
+    return 0;
+}
+
 const VMStateDescription vmstate_arm_cpu = {
     .name = "cpu",
-    .version_id = 11,
+    .version_id = 12,
-    .minimum_version_id = 11,
+    .minimum_version_id = 12,
-    .minimum_version_id_old = 11,
+    .minimum_version_id_old = 12,
+    .pre_save = cpu_pre_save,
+    .post_load = cpu_post_load,
     .fields = (VMStateField[]) {
         VMSTATE_UINT32_ARRAY(env.regs, ARMCPU, 16),
         {
@@ -169,50 +223,16 @@ const VMStateDescription vmstate_arm_cpu = {
         VMSTATE_UINT32_ARRAY(env.banked_r14, ARMCPU, 6),
         VMSTATE_UINT32_ARRAY(env.usr_regs, ARMCPU, 5),
         VMSTATE_UINT32_ARRAY(env.fiq_regs, ARMCPU, 5),
-        VMSTATE_UINT32(env.cp15.c0_cpuid, ARMCPU),
+        /* The length-check must come before the arrays to avoid
-        VMSTATE_UINT32(env.cp15.c0_cssel, ARMCPU),
+         * incoming data possibly overflowing the array.
-        VMSTATE_UINT32(env.cp15.c1_sys, ARMCPU),
+         */
-        VMSTATE_UINT32(env.cp15.c1_coproc, ARMCPU),
+        VMSTATE_INT32_LE(cpreg_vmstate_array_len, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c1_xscaleauxcr, ARMCPU),
+        VMSTATE_VARRAY_INT32(cpreg_vmstate_indexes, ARMCPU,
-        VMSTATE_UINT32(env.cp15.c1_scr, ARMCPU),
+                             cpreg_vmstate_array_len,
-        VMSTATE_UINT32(env.cp15.c2_base0, ARMCPU),
+                             0, vmstate_info_uint64, uint64_t),
-        VMSTATE_UINT32(env.cp15.c2_base0_hi, ARMCPU),
+        VMSTATE_VARRAY_INT32(cpreg_vmstate_values, ARMCPU,
-        VMSTATE_UINT32(env.cp15.c2_base1, ARMCPU),
+                             cpreg_vmstate_array_len,
-        VMSTATE_UINT32(env.cp15.c2_base1_hi, ARMCPU),
+                             0, vmstate_info_uint64, uint64_t),
-        VMSTATE_UINT32(env.cp15.c2_control, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c2_mask, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c2_base_mask, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c2_data, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c2_insn, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c3, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c5_insn, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c5_data, ARMCPU),
-        VMSTATE_UINT32_ARRAY(env.cp15.c6_region, ARMCPU, 8),
-        VMSTATE_UINT32(env.cp15.c6_insn, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c6_data, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c7_par, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c7_par_hi, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c9_insn, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c9_data, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c9_pmcr, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c9_pmcnten, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c9_pmovsr, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c9_pmxevtyper, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c9_pmuserenr, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c9_pminten, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c13_fcse, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c13_context, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c13_tls1, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c13_tls2, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c13_tls3, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c15_cpar, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c15_ticonfig, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c15_i_max, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c15_i_min, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c15_threadid, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c15_power_control, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c15_diagnostic, ARMCPU),
-        VMSTATE_UINT32(env.cp15.c15_power_diagnostic, ARMCPU),
         VMSTATE_UINT32(env.exclusive_addr, ARMCPU),
         VMSTATE_UINT32(env.exclusive_val, ARMCPU),
         VMSTATE_UINT32(env.exclusive_high, ARMCPU),