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>

1 files changed, 163 insertions, 1 deletions

diff --git a/target-arm/kvm.c b/target-arm/kvm.c
index f427537..66ce67a 100644
--- a/target-arm/kvm.c
+++ b/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;