KVM based VM example cpde的示例代码

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/* Sample code for /dev/kvm API * * Copyright (c) 2015 Intel Corporation * Author: Josh Triplett  * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to * deal in the Software without restriction, including without limitation the * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or * sell copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. */#include #include #include #include #include #include #include #include #include #include #include int main(void){    int kvm, vmfd, vcpufd, ret;    const uint8_t code[] = {        0xba, 0xf8, 0x03, /* mov $0x3f8, %dx */        0x00, 0xd8,       /* add %bl, %al */        0x04, '0',        /* add $'0', %al */        0xee,             /* out %al, (%dx) */        0xb0, '\n',       /* mov $'\n', %al */        0xee,             /* out %al, (%dx) */        0xf4,             /* hlt */    };    uint8_t *mem;    struct kvm_sregs sregs;    size_t mmap_size;    struct kvm_run *run;    kvm = open("/dev/kvm", O_RDWR | O_CLOEXEC);    if (kvm == -1)        err(1, "/dev/kvm");    /* Make sure we have the stable version of the API */    ret = ioctl(kvm, KVM_GET_API_VERSION, NULL);    if (ret == -1)        err(1, "KVM_GET_API_VERSION");    if (ret != 12)        errx(1, "KVM_GET_API_VERSION %d, expected 12", ret);    vmfd = ioctl(kvm, KVM_CREATE_VM, (unsigned long)0);    if (vmfd == -1)        err(1, "KVM_CREATE_VM");    /* Allocate one aligned page of guest memory to hold the code. */    mem = mmap(NULL, 0x1000, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0);    if (!mem)        err(1, "allocating guest memory");    memcpy(mem, code, sizeof(code));    /* Map it to the second page frame (to avoid the real-mode IDT at 0). */    struct kvm_userspace_memory_region region = {        .slot = 0,        .guest_phys_addr = 0x1000,        .memory_size = 0x1000,        .userspace_addr = (uint64_t)mem,    };    ret = ioctl(vmfd, KVM_SET_USER_MEMORY_REGION, ®ion);    if (ret == -1)        err(1, "KVM_SET_USER_MEMORY_REGION");    vcpufd = ioctl(vmfd, KVM_CREATE_VCPU, (unsigned long)0);    if (vcpufd == -1)        err(1, "KVM_CREATE_VCPU");    /* Map the shared kvm_run structure and following data. */    ret = ioctl(kvm, KVM_GET_VCPU_MMAP_SIZE, NULL);    if (ret == -1)        err(1, "KVM_GET_VCPU_MMAP_SIZE");    mmap_size = ret;    if (mmap_size < sizeof(*run))        errx(1, "KVM_GET_VCPU_MMAP_SIZE unexpectedly small");    run = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, vcpufd, 0);    if (!run)        err(1, "mmap vcpu");    /* Initialize CS to point at 0, via a read-modify-write of sregs. */    ret = ioctl(vcpufd, KVM_GET_SREGS, &sregs);    if (ret == -1)        err(1, "KVM_GET_SREGS");    sregs.cs.base = 0;    sregs.cs.selector = 0;    ret = ioctl(vcpufd, KVM_SET_SREGS, &sregs);    if (ret == -1)        err(1, "KVM_SET_SREGS");    /* Initialize registers: instruction pointer for our code, addends, and     * initial flags required by x86 architecture. */    struct kvm_regs regs = {        .rip = 0x1000,        .rax = 2,        .rbx = 2,        .rflags = 0x2,    };    ret = ioctl(vcpufd, KVM_SET_REGS, ®s);    if (ret == -1)        err(1, "KVM_SET_REGS");    /* Repeatedly run code and handle VM exits. */    while (1) {        ret = ioctl(vcpufd, KVM_RUN, NULL);        if (ret == -1)            err(1, "KVM_RUN");        switch (run->exit_reason) {        case KVM_EXIT_HLT:            puts("KVM_EXIT_HLT");            return 0;        case KVM_EXIT_IO:            if (run->io.direction == KVM_EXIT_IO_OUT && run->io.size == 1 && run->io.port == 0x3f8 && run->io.count == 1)                putchar(*(((char *)run) + run->io.data_offset));            else                errx(1, "unhandled KVM_EXIT_IO");            break;        case KVM_EXIT_FAIL_ENTRY:            errx(1, "KVM_EXIT_FAIL_ENTRY: hardware_entry_failure_reason = 0x%llx",                 (unsigned long long)run->fail_entry.hardware_entry_failure_reason);        case KVM_EXIT_INTERNAL_ERROR:            errx(1, "KVM_EXIT_INTERNAL_ERROR: suberror = 0x%x", run->internal.suberror);        default:            errx(1, "exit_reason = 0x%x", run->exit_reason);        }    }}

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