101 lines
2.4 KiB
C
101 lines
2.4 KiB
C
#include <linux/kvm.h>
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#include <stdint.h>
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#include <unistd.h>
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#include <assert.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/ioctl.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <fcntl.h>
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#define MSIZE 0x10000 // size of conventional memory
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int main(int argc, char** argv) {
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struct stat s;
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int ret = stat(argv[1], &s);
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if(ret) exit(!!printf("invalid file!\n"));
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int kvm = open("/dev/kvm", O_RDWR | O_CLOEXEC);
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assert((ioctl(kvm, KVM_CHECK_EXTENSION, KVM_CAP_USER_MEMORY) ^ ioctl(kvm, KVM_GET_API_VERSION, NULL)) == 13);
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int vmfd = ioctl(kvm, KVM_CREATE_VM, (unsigned long)0),
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vcpufd = ioctl(vmfd, KVM_CREATE_VCPU, (unsigned long)0),
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codefd = open(argv[1], O_RDONLY); // load boot sector from file
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uint8_t* mem = mmap(NULL, MSIZE, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); // allocate conventional memory for vm
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mz* mzbuf = malloc(s.st_size);
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read(codefd, mzbuf, s.st_size);
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close(codefd);
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mz_start ms;
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uint32_t mzsz = loadmz(mzbuf, mem, 0x40, &ms);
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struct kvm_userspace_memory_region memmap[2] = {
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{
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.guest_phys_addr = 0,
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.memory_size = 0xA0000,
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.userspace_addr = (uint64_t)mem,
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},
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/*{ // implied map
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.guest_phys_addr = 0xA0000,
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.memory_size = 0x20000,
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.userspace_addr = (uint64_t)mem,
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},*/
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{
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.guest_phys_addr = 0xC0000,
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.memory_size = 0x40000,
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.userspace_addr = (uint64_t)mem + 0xC0000,
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},
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};
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for(int i = 0; i < 2; i++) {
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memmap[i].slot = i; // id of memory mapping
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ioctl(vmfd, KVM_SET_USER_MEMORY_REGION, memmap[i]);
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}
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struct kvm_sregs sregs;
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struct kvm_run* run;
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size_t run_size = ioctl(kvm, KVM_GET_VCPU_MMAP_SIZE, NULL); // size of struct is. determined at runtime for some reason?
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run = mmap(NULL, run_size, PROT_READ | PROT_WRITE, MAP_SHARED, vcpufd, 0);
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ioctl(vcpufd, KVM_GET_SREGS, &sregs);
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sregs.cs.base = ms.cs;
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sregs.ss.base = ms.ss;
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sregs.cs.selector = 0; // probably protected mode related?
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sregs.ss.selector = 0;
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ioctl(vcpufd, KVM_SET_SREGS, &sregs);
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struct kvm_regs regs = {
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.rip = ms.ip,
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.rsp = ms.sp,
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.rflags = 0x2,
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};
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ioctl(vcpufd, KVM_SET_REGS, ®s);
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while(1) {
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ret = ioctl(vcpufd, KVM_RUN, NULL);
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if(ret == -1) exit(!!printf("kvm error\n"));
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switch (run->exit_reason) {
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case KVM_EXIT_HLT:
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exit(!printf("got instruction `hlt`, exiting\n"));
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break;
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case KVM_EXIT_IO:
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break;
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default:
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exit(printf("vmexit\n"));
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break;
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}
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}
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}
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