[PATCH kvm-unit-tests 2/4] Introduce a C++ wrapper for the kvm APIs

[Avi Kivity <avi@redhat.com>]

Introduce exception-safe objects for calling system, vm, and vcpu ioctls.

Signed-off-by: Avi Kivity <avi@redhat.com>
---
 api/kvmxx.cc |  168 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 api/kvmxx.h  |   80 +++++++++++++++++++++++++++
 2 files changed, 248 insertions(+), 0 deletions(-)
 create mode 100644 api/kvmxx.cc
 create mode 100644 api/kvmxx.h

diff --git a/api/kvmxx.cc b/api/kvmxx.cc
new file mode 100644
index 0000000..2f8fc27
--- /dev/null
+++ b/api/kvmxx.cc
@@ -0,0 +1,168 @@
+#include "kvmxx.h"
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <memory>
+#include <algorithm>
+
+namespace kvm {
+
+static long check_error(long r)
+{
+    if (r == -1) {
+	throw errno;
+    }
+    return r;
+}
+
+fd::fd(int fd)
+    : _fd(fd)
+{
+}
+
+fd::fd(const fd& other)
+    : _fd(::dup(other._fd))
+{
+    check_error(_fd);
+}
+
+fd::fd(std::string device_node, int flags)
+    : _fd(::open(device_node.c_str(), flags))
+{
+    check_error(_fd);
+}
+
+long fd::ioctl(unsigned nr, long arg)
+{
+    return check_error(::ioctl(_fd, nr, arg));
+}
+
+vcpu::vcpu(vm& vm, int id)
+    : _vm(vm), _fd(vm._fd.ioctl(KVM_CREATE_VCPU, id)), _shared(NULL)
+{
+    unsigned mmap_size = _vm._system._fd.ioctl(KVM_GET_VCPU_MMAP_SIZE, 0);
+    kvm_run *shared = static_cast<kvm_run*>(::mmap(NULL, mmap_size,
+						   PROT_READ | PROT_WRITE,
+						   MAP_SHARED,
+						   _fd.get(), 0));
+    if (shared == MAP_FAILED) {
+	throw errno;
+    }
+    _shared = shared;
+}
+
+vcpu::~vcpu()
+{
+    unsigned mmap_size = _vm._system._fd.ioctl(KVM_GET_VCPU_MMAP_SIZE, 0);
+    munmap(_shared, mmap_size);
+}
+
+void vcpu::run()
+{
+    _fd.ioctl(KVM_RUN, 0);
+}
+
+kvm_regs vcpu::regs()
+{
+    kvm_regs regs;
+    _fd.ioctlp(KVM_GET_REGS, &regs);
+    return regs;
+}
+
+void vcpu::set_regs(const kvm_regs& regs)
+{
+    _fd.ioctlp(KVM_SET_REGS, const_cast<kvm_regs*>(&regs));
+}
+
+kvm_sregs vcpu::sregs()
+{
+    kvm_sregs sregs;
+    _fd.ioctlp(KVM_GET_SREGS, &sregs);
+    return sregs;
+}
+
+void vcpu::set_sregs(const kvm_sregs& sregs)
+{
+    _fd.ioctlp(KVM_SET_SREGS, const_cast<kvm_sregs*>(&sregs));
+}
+
+kvm_msrs* vcpu::alloc_msr_list(size_t nmsrs)
+{
+    size_t size = sizeof(kvm_msrs) + sizeof(kvm_msr_entry) * nmsrs;
+    kvm_msrs* ret = static_cast<kvm_msrs*>(malloc(size));
+    if (!ret) {
+	throw ENOMEM;
+    }
+    return ret;
+}
+
+std::vector<kvm_msr_entry> vcpu::msrs(std::vector<uint32_t> indices)
+{
+    std::auto_ptr<kvm_msrs> msrs(alloc_msr_list(indices.size()));
+    msrs->nmsrs = indices.size();
+    for (unsigned i = 0; i < msrs->nmsrs; ++i) {
+	msrs->entries[i].index = indices[i];
+    }
+    _fd.ioctlp(KVM_GET_MSRS, msrs.get());
+    return std::vector<kvm_msr_entry>(msrs->entries,
+				      msrs->entries + msrs->nmsrs);
+}
+
+void vcpu::set_msrs(const std::vector<kvm_msr_entry>& msrs)
+{
+    std::auto_ptr<kvm_msrs> _msrs(alloc_msr_list(msrs.size()));
+    _msrs->nmsrs = msrs.size();
+    std::copy(msrs.begin(), msrs.end(), _msrs->entries);
+    _fd.ioctlp(KVM_SET_MSRS, _msrs.get());
+}
+
+void vcpu::set_debug(uint64_t dr[8], bool enabled, bool singlestep)
+{
+    kvm_guest_debug gd;
+
+    gd.control = 0;
+    if (enabled) {
+	gd.control |= KVM_GUESTDBG_ENABLE;
+    }
+    if (singlestep) {
+	gd.control |= KVM_GUESTDBG_SINGLESTEP;
+    }
+    for (int i = 0; i < 8; ++i) {
+	gd.arch.debugreg[i] = dr[i];
+    }
+    _fd.ioctlp(KVM_SET_GUEST_DEBUG, &gd);
+}
+
+vm::vm(system& system)
+    : _system(system), _fd(system._fd.ioctl(KVM_CREATE_VM, 0))
+{
+}
+
+void vm::set_memory_region(int slot, void *addr, uint64_t gpa, size_t len)
+{
+    struct kvm_userspace_memory_region umr;
+
+    umr.slot = slot;
+    umr.flags = 0;
+    umr.guest_phys_addr = gpa;
+    umr.memory_size = len;
+    umr.userspace_addr = reinterpret_cast<uint64_t>(addr);
+    _fd.ioctlp(KVM_SET_USER_MEMORY_REGION, &umr);
+}
+
+void vm::set_tss_addr(uint32_t addr)
+{
+    _fd.ioctl(KVM_SET_TSS_ADDR, addr);
+}
+
+system::system(std::string device_node)
+    : _fd(device_node, O_RDWR)
+{
+}
+
+bool system::check_extension(int extension)
+{
+    return _fd.ioctl(KVM_CHECK_EXTENSION, extension);
+}
+
+};
diff --git a/api/kvmxx.h b/api/kvmxx.h
new file mode 100644
index 0000000..716e400
--- /dev/null
+++ b/api/kvmxx.h
@@ -0,0 +1,80 @@
+#ifndef KVMXX_H
+#define KVMXX_H
+
+#include <string>
+#include <signal.h>
+#include <unistd.h>
+#include <vector>
+#include <errno.h>
+#include <linux/kvm.h>
+#include <stdint.h>
+
+namespace kvm {
+
+class system;
+class vm;
+class vcpu;
+class fd;
+
+class fd {
+public:
+    explicit fd(int n);
+    explicit fd(std::string path, int flags);
+    fd(const fd& other);
+    ~fd() { ::close(_fd); }
+    int get() { return _fd; }
+    long ioctl(unsigned nr, long arg);
+    long ioctlp(unsigned nr, void *arg) {
+	return ioctl(nr, reinterpret_cast<long>(arg));
+    }
+private:
+    int _fd;
+};
+
+class vcpu {
+public:
+    vcpu(vm& vm, int fd);
+    ~vcpu();
+    void run();
+    kvm_run *shared();
+    kvm_regs regs();
+    void set_regs(const kvm_regs& regs);
+    kvm_sregs sregs();
+    void set_sregs(const kvm_sregs& sregs);
+    std::vector<kvm_msr_entry> msrs(std::vector<uint32_t> indices);
+    void set_msrs(const std::vector<kvm_msr_entry>& msrs);
+    void set_debug(uint64_t dr[8], bool enabled, bool singlestep);
+private:
+    static kvm_msrs* alloc_msr_list(size_t nmsrs);
+private:
+    vm& _vm;
+    fd _fd;
+    kvm_run *_shared;
+    friend class vm;
+};
+
+class vm {
+public:
+    explicit vm(system& system);
+    void set_memory_region(int slot, void *addr, uint64_t gpa, size_t len);
+    void set_tss_addr(uint32_t addr);
+private:
+    system& _system;
+    fd _fd;
+    friend class system;
+    friend class vcpu;
+};
+
+class system {
+public:
+    explicit system(std::string device_node = "/dev/kvm");
+    bool check_extension(int extension);
+private:
+    fd _fd;
+    friend class vcpu;
+    friend class vm;
+};
+
+};
+
+#endif
-- 
1.7.1