target-arm: Initialize cpreg list from KVM when using KVM

When using KVM, use the kernel's initial state to set up the
cpreg list, and sync to and from the kernel when doing
migration.

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

target-arm/Makefile.objs

@@ -1,5 +1,6 @@
 obj-y += arm-semi.o
 obj-$(CONFIG_SOFTMMU) += machine.o
 obj-$(CONFIG_KVM) += kvm.o
+obj-$(CONFIG_NO_KVM) += kvm-stub.o
 obj-y += translate.o op_helper.o helper.o cpu.o
 obj-y += neon_helper.o iwmmxt_helper.o

target-arm/kvm-stub.c

@@ -0,0 +1,23 @@
+/*
+ * QEMU KVM ARM specific function stubs
+ *
+ * Copyright Linaro Limited 2013
+ *
+ * Author: Peter Maydell <peter.maydell@linaro.org>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+#include "qemu-common.h"
+#include "kvm_arm.h"
+
+bool write_kvmstate_to_list(ARMCPU *cpu)
+{
+    abort();
+}
+
+bool write_list_to_kvmstate(ARMCPU *cpu)
+{
+    abort();
+}

target-arm/kvm.c

@@ -50,12 +50,35 @@ unsigned long kvm_arch_vcpu_id(CPUState *cpu)
     return cpu->cpu_index;
 }
 
+static bool reg_syncs_via_tuple_list(uint64_t regidx)
+{
+    /* Return true if the regidx is a register we should synchronize
+     * via the cpreg_tuples array (ie is not a core reg we sync by
+     * hand in kvm_arch_get/put_registers())
+     */
+    switch (regidx & KVM_REG_ARM_COPROC_MASK) {
+    case KVM_REG_ARM_CORE:
+    case KVM_REG_ARM_VFP:
+        return false;
+    default:
+        return true;
+    }
+}
+
+static int compare_u64(const void *a, const void *b)
+{
+    return *(uint64_t *)a - *(uint64_t *)b;
+}
+
 int kvm_arch_init_vcpu(CPUState *cs)
 {
     struct kvm_vcpu_init init;
-    int ret;
+    int i, ret, arraylen;
     uint64_t v;
     struct kvm_one_reg r;
+    struct kvm_reg_list rl;
+    struct kvm_reg_list *rlp;
+    ARMCPU *cpu = ARM_CPU(cs);
 
     init.target = KVM_ARM_TARGET_CORTEX_A15;
     memset(init.features, 0, sizeof(init.features));
@@ -74,6 +97,73 @@ int kvm_arch_init_vcpu(CPUState *cs)
     if (ret == -ENOENT) {
         return -EINVAL;
     }
+
+    /* Populate the cpreg list based on the kernel's idea
+     * of what registers exist (and throw away the TCG-created list).
+     */
+    rl.n = 0;
+    ret = kvm_vcpu_ioctl(cs, KVM_GET_REG_LIST, &rl);
+    if (ret != -E2BIG) {
+        return ret;
+    }
+    rlp = g_malloc(sizeof(struct kvm_reg_list) + rl.n * sizeof(uint64_t));
+    rlp->n = rl.n;
+    ret = kvm_vcpu_ioctl(cs, KVM_GET_REG_LIST, rlp);
+    if (ret) {
+        goto out;
+    }
+    /* Sort the list we get back from the kernel, since cpreg_tuples
+     * must be in strictly ascending order.
+     */
+    qsort(&rlp->reg, rlp->n, sizeof(rlp->reg[0]), compare_u64);
+
+    for (i = 0, arraylen = 0; i < rlp->n; i++) {
+        if (!reg_syncs_via_tuple_list(rlp->reg[i])) {
+            continue;
+        }
+        switch (rlp->reg[i] & KVM_REG_SIZE_MASK) {
+        case KVM_REG_SIZE_U32:
+        case KVM_REG_SIZE_U64:
+            break;
+        default:
+            fprintf(stderr, "Can't handle size of register in kernel list\n");
+            ret = -EINVAL;
+            goto out;
+        }
+
+        arraylen++;
+    }
+
+    cpu->cpreg_indexes = g_renew(uint64_t, cpu->cpreg_indexes, arraylen);
+    cpu->cpreg_values = g_renew(uint64_t, cpu->cpreg_values, arraylen);
+    cpu->cpreg_vmstate_indexes = g_renew(uint64_t, cpu->cpreg_vmstate_indexes,
+                                         arraylen);
+    cpu->cpreg_vmstate_values = g_renew(uint64_t, cpu->cpreg_vmstate_values,
+                                        arraylen);
+    cpu->cpreg_array_len = arraylen;
+    cpu->cpreg_vmstate_array_len = arraylen;
+
+    for (i = 0, arraylen = 0; i < rlp->n; i++) {
+        uint64_t regidx = rlp->reg[i];
+        if (!reg_syncs_via_tuple_list(regidx)) {
+            continue;
+        }
+        cpu->cpreg_indexes[arraylen] = regidx;
+        arraylen++;
+    }
+    assert(cpu->cpreg_array_len == arraylen);
+
+    if (!write_kvmstate_to_list(cpu)) {
+        /* Shouldn't happen unless kernel is inconsistent about
+         * what registers exist.
+         */
+        fprintf(stderr, "Initial read of kernel register state failed\n");
+        ret = -EINVAL;
+        goto out;
+    }
+
+out:
+    g_free(rlp);
     return ret;
 }
 
@@ -163,6 +253,78 @@ void kvm_arm_register_device(MemoryRegion *mr, uint64_t devid)
     QSLIST_INSERT_HEAD(&kvm_devices_head, kd, entries);
 }
 
+bool write_kvmstate_to_list(ARMCPU *cpu)
+{
+    CPUState *cs = CPU(cpu);
+    int i;
+    bool ok = true;
+
+    for (i = 0; i < cpu->cpreg_array_len; i++) {
+        struct kvm_one_reg r;
+        uint64_t regidx = cpu->cpreg_indexes[i];
+        uint32_t v32;
+        int ret;
+
+        r.id = regidx;
+
+        switch (regidx & KVM_REG_SIZE_MASK) {
+        case KVM_REG_SIZE_U32:
+            r.addr = (uintptr_t)&v32;
+            ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
+            if (!ret) {
+                cpu->cpreg_values[i] = v32;
+            }
+            break;
+        case KVM_REG_SIZE_U64:
+            r.addr = (uintptr_t)(cpu->cpreg_values + i);
+            ret = kvm_vcpu_ioctl(cs, KVM_GET_ONE_REG, &r);
+            break;
+        default:
+            abort();
+        }
+        if (ret) {
+            ok = false;
+        }
+    }
+    return ok;
+}
+
+bool write_list_to_kvmstate(ARMCPU *cpu)
+{
+    CPUState *cs = CPU(cpu);
+    int i;
+    bool ok = true;
+
+    for (i = 0; i < cpu->cpreg_array_len; i++) {
+        struct kvm_one_reg r;
+        uint64_t regidx = cpu->cpreg_indexes[i];
+        uint32_t v32;
+        int ret;
+
+        r.id = regidx;
+        switch (regidx & KVM_REG_SIZE_MASK) {
+        case KVM_REG_SIZE_U32:
+            v32 = cpu->cpreg_values[i];
+            r.addr = (uintptr_t)&v32;
+            break;
+        case KVM_REG_SIZE_U64:
+            r.addr = (uintptr_t)(cpu->cpreg_values + i);
+            break;
+        default:
+            abort();
+        }
+        ret = kvm_vcpu_ioctl(cs, KVM_SET_ONE_REG, &r);
+        if (ret) {
+            /* We might fail for "unknown register" and also for
+             * "you tried to set a register which is constant with
+             * a different value from what it actually contains".
+             */
+            ok = false;
+        }
+    }
+    return ok;
+}
+
 typedef struct Reg {
     uint64_t id;
     int offset;

target-arm/kvm_arm.h

@@ -29,4 +29,37 @@
  */
 void kvm_arm_register_device(MemoryRegion *mr, uint64_t devid);
 
+/**
+ * write_list_to_kvmstate:
+ * @cpu: ARMCPU
+ *
+ * For each register listed in the ARMCPU cpreg_indexes list, write
+ * its value from the cpreg_values list into the kernel (via ioctl).
+ * This updates KVM's working data structures from TCG data or
+ * from incoming migration state.
+ *
+ * Returns: true if all register values were updated correctly,
+ * false if some register was unknown to the kernel or could not
+ * be written (eg constant register with the wrong value).
+ * Note that we do not stop early on failure -- we will attempt
+ * writing all registers in the list.
+ */
+bool write_list_to_kvmstate(ARMCPU *cpu);
+
+/**
+ * write_kvmstate_to_list:
+ * @cpu: ARMCPU
+ *
+ * For each register listed in the ARMCPU cpreg_indexes list, write
+ * its value from the kernel into the cpreg_values list. This is used to
+ * copy info from KVM's working data structures into TCG 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_kvmstate_to_list(ARMCPU *cpu);
+
 #endif

target-arm/machine.c

@@ -1,5 +1,7 @@
 #include "hw/hw.h"
 #include "hw/boards.h"
+#include "sysemu/kvm.h"
+#include "kvm_arm.h"
 
 static bool vfp_needed(void *opaque)
 {
@@ -152,9 +154,16 @@ static void cpu_pre_save(void *opaque)
 {
     ARMCPU *cpu = opaque;
 
-    if (!write_cpustate_to_list(cpu)) {
-        /* This should never fail. */
-        abort();
+    if (kvm_enabled()) {
+        if (!write_kvmstate_to_list(cpu)) {
+            /* This should never fail */
+            abort();
+        }
+    } else {
+        if (!write_cpustate_to_list(cpu)) {
+            /* This should never fail. */
+            abort();
+        }
     }
 
     cpu->cpreg_vmstate_array_len = cpu->cpreg_array_len;
@@ -193,8 +202,19 @@ static int cpu_post_load(void *opaque, int version_id)
         v++;
     }
 
-    if (!write_list_to_cpustate(cpu)) {
-        return -1;
+    if (kvm_enabled()) {
+        if (!write_list_to_kvmstate(cpu)) {
+            return -1;
+        }
+        /* Note that it's OK for the TCG side not to know about
+         * every register in the list; KVM is authoritative if
+         * we're using it.
+         */
+        write_list_to_cpustate(cpu);
+    } else {
+        if (!write_list_to_cpustate(cpu)) {
+            return -1;
+        }
     }
 
     return 0;