Archipelago » qemu

bool kvm_arm_create_scratch_host_vcpu(const uint32_t *cpus_to_try,

                                      int *fdarray,

                                      struct kvm_vcpu_init *init)

{

    int ret, kvmfd = -1, vmfd = -1, cpufd = -1;

    kvmfd = qemu_open("/dev/kvm", O_RDWR);

    if (kvmfd < 0) {

        goto err;

    }

    vmfd = ioctl(kvmfd, KVM_CREATE_VM, 0);

    if (vmfd < 0) {

        goto err;

    }

    cpufd = ioctl(vmfd, KVM_CREATE_VCPU, 0);

    if (cpufd < 0) {

        goto err;

    }

    ret = ioctl(vmfd, KVM_ARM_PREFERRED_TARGET, init);

    if (ret >= 0) {

        ret = ioctl(cpufd, KVM_ARM_VCPU_INIT, init);

        if (ret < 0) {

            goto err;

        }

    } else {

        /* Old kernel which doesn't know about the

         * PREFERRED_TARGET ioctl: we know it will only support

         * creating one kind of guest CPU which is its preferred

         * CPU type.

         */

        while (*cpus_to_try != QEMU_KVM_ARM_TARGET_NONE) {

            init->target = *cpus_to_try++;

            memset(init->features, 0, sizeof(init->features));

            ret = ioctl(cpufd, KVM_ARM_VCPU_INIT, init);

            if (ret >= 0) {

                break;

            }

        }

        if (ret < 0) {

            goto err;

        }

    }

    fdarray[0] = kvmfd;

    fdarray[1] = vmfd;

    fdarray[2] = cpufd;

    return true;

err:

    if (cpufd >= 0) {

        close(cpufd);

    }

    if (vmfd >= 0) {

        close(vmfd);

    }

    if (kvmfd >= 0) {

        close(kvmfd);

    }

    return false;

}

void kvm_arm_destroy_scratch_host_vcpu(int *fdarray)

{

    int i;

    for (i = 2; i >= 0; i--) {

        close(fdarray[i]);

    }

}

static inline void set_feature(uint64_t *features, int feature)

{

    *features |= 1ULL << feature;

}

bool kvm_arm_get_host_cpu_features(ARMHostCPUClass *ahcc)

{

    /* Identify the feature bits corresponding to the host CPU, and

     * fill out the ARMHostCPUClass fields accordingly. To do this

     * we have to create a scratch VM, create a single CPU inside it,

     * and then query that CPU for the relevant ID registers.

     */

    int i, ret, fdarray[3];

    uint32_t midr, id_pfr0, id_isar0, mvfr1;

    uint64_t features = 0;

    /* Old kernels may not know about the PREFERRED_TARGET ioctl: however

     * we know these will only support creating one kind of guest CPU,

     * which is its preferred CPU type.

     */

    static const uint32_t cpus_to_try[] = {

        QEMU_KVM_ARM_TARGET_CORTEX_A15,

        QEMU_KVM_ARM_TARGET_NONE

    };

    struct kvm_vcpu_init init;

    struct kvm_one_reg idregs[] = {

        {

            .id = KVM_REG_ARM | KVM_REG_SIZE_U32

            | ENCODE_CP_REG(15, 0, 0, 0, 0, 0),

            .addr = (uintptr_t)&midr,

        },

        {

            .id = KVM_REG_ARM | KVM_REG_SIZE_U32

            | ENCODE_CP_REG(15, 0, 0, 1, 0, 0),

            .addr = (uintptr_t)&id_pfr0,

        },

        {

            .id = KVM_REG_ARM | KVM_REG_SIZE_U32

            | ENCODE_CP_REG(15, 0, 0, 2, 0, 0),

            .addr = (uintptr_t)&id_isar0,

        },

        {

            .id = KVM_REG_ARM | KVM_REG_SIZE_U32

            | KVM_REG_ARM_VFP | KVM_REG_ARM_VFP_MVFR1,

            .addr = (uintptr_t)&mvfr1,

        },

    };

    if (!kvm_arm_create_scratch_host_vcpu(cpus_to_try, fdarray, &init)) {

        return false;

    }

    ahcc->target = init.target;

    /* This is not strictly blessed by the device tree binding docs yet,

     * but in practice the kernel does not care about this string so

     * there is no point maintaining an KVM_ARM_TARGET_* -> string table.

     */

    ahcc->dtb_compatible = "arm,arm-v7";

    for (i = 0; i < ARRAY_SIZE(idregs); i++) {

        ret = ioctl(fdarray[2], KVM_GET_ONE_REG, &idregs[i]);

        if (ret) {

            break;

        }

    }

    kvm_arm_destroy_scratch_host_vcpu(fdarray);

    if (ret) {

        return false;

    }

    /* Now we've retrieved all the register information we can

     * set the feature bits based on the ID register fields.

     * We can assume any KVM supporting CPU is at least a v7

     * with VFPv3, LPAE and the generic timers; this in turn implies

     * most of the other feature bits, but a few must be tested.

     */

    set_feature(&features, ARM_FEATURE_V7);

    set_feature(&features, ARM_FEATURE_VFP3);

    set_feature(&features, ARM_FEATURE_LPAE);

    set_feature(&features, ARM_FEATURE_GENERIC_TIMER);

    switch (extract32(id_isar0, 24, 4)) {

    case 1:

        set_feature(&features, ARM_FEATURE_THUMB_DIV);

        break;

    case 2:

        set_feature(&features, ARM_FEATURE_ARM_DIV);

        set_feature(&features, ARM_FEATURE_THUMB_DIV);

        break;

    default:

        break;

    }

    if (extract32(id_pfr0, 12, 4) == 1) {

        set_feature(&features, ARM_FEATURE_THUMB2EE);

    }

    if (extract32(mvfr1, 20, 4) == 1) {

        set_feature(&features, ARM_FEATURE_VFP_FP16);

    }

    if (extract32(mvfr1, 12, 4) == 1) {

        set_feature(&features, ARM_FEATURE_NEON);

    }

    if (extract32(mvfr1, 28, 4) == 1) {

        /* FMAC support implies VFPv4 */

        set_feature(&features, ARM_FEATURE_VFP4);

    }

    ahcc->features = features;

    return true;

}

static void kvm_arm_host_cpu_class_init(ObjectClass *oc, void *data)

{

    ARMHostCPUClass *ahcc = ARM_HOST_CPU_CLASS(oc);

    /* All we really need to set up for the 'host' CPU

     * is the feature bits -- we rely on the fact that the

     * various ID register values in ARMCPU are only used for

     * TCG CPUs.

     */

    if (!kvm_arm_get_host_cpu_features(ahcc)) {

        fprintf(stderr, "Failed to retrieve host CPU features!\n");

        abort();

    }

}

static void kvm_arm_host_cpu_initfn(Object *obj)

{

    ARMHostCPUClass *ahcc = ARM_HOST_CPU_GET_CLASS(obj);

    ARMCPU *cpu = ARM_CPU(obj);

    CPUARMState *env = &cpu->env;

    cpu->kvm_target = ahcc->target;

    cpu->dtb_compatible = ahcc->dtb_compatible;

    env->features = ahcc->features;

}

static const TypeInfo host_arm_cpu_type_info = {

    .name = TYPE_ARM_HOST_CPU,

    .parent = TYPE_ARM_CPU,

    .instance_init = kvm_arm_host_cpu_initfn,

    .class_init = kvm_arm_host_cpu_class_init,

    .class_size = sizeof(ARMHostCPUClass),

};

    type_register_static(&host_arm_cpu_type_info);