[Libvir] New vs old-style hypercalls

[Richard W.M. Jones]

In xen_internal.c we've got code which claims to sniff out whether we are using new-style hypercall ioctls or old-style hypercall ioctls.

    hc.op = __HYPERVISOR_xen_version;
    hc.arg[0] = (unsigned long) XENVER_version;
    hc.arg[1] = 0;

    cmd = IOCTL_PRIVCMD_HYPERCALL;
    ret = ioctl(fd, cmd, (unsigned long) &hc);

    if ((ret != -1) && (ret != 0)) {
#ifdef DEBUG
        fprintf(stderr, "Using new hypervisor call: %X\n", ret);
#endif
        hv_version = ret;
        xen_ioctl_hypercall_cmd = cmd;
        goto detect_v2;
    }

    /*
     * check if the old hypercall are actually working
     */
    v0_hc.op = __HYPERVISOR_xen_version;
    v0_hc.arg[0] = (unsigned long) XENVER_version;
    v0_hc.arg[1] = 0;
    cmd = _IOC(_IOC_NONE, 'P', 0, sizeof(v0_hypercall_t));
    ret = ioctl(fd, cmd, (unsigned long) &v0_hc);



From <xen/linux/privcmd.h>:

    typedef struct privcmd_hypercall
    {
        __u64 op;
        __u64 arg[5];
    } privcmd_hypercall_t;

    #define IOCTL_PRIVCMD_HYPERCALL                                 \
        _IOC(_IOC_NONE, 'P', 0, sizeof(privcmd_hypercall_t))

From src/xen_internal.c:

    typedef struct v0_hypercall_struct {
        unsigned long op;
        unsigned long arg[5];
    } v0_hypercall_t;

    cmd = _IOC(_IOC_NONE, 'P', 0, sizeof(v0_hypercall_t));

On 64 bit platforms, both structures will be the same size.

Rich.

--
Emerging Technologies, Red Hat - http://et.redhat.com/~rjones/
Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod
Street, Windsor, Berkshire, SL4 1TE, United Kingdom.  Registered in
England and Wales under Company Registration No. 03798903

But on 64 bit platforms (not 32 bit) cmd will be identical, so we'll just be trying the same ioctl twice.

smime.p7s
Description: S/MIME Cryptographic Signature

--
Libvir-list mailing list
Libvir-list@redhat.com
https://www.redhat.com/mailman/listinfo/libvir-list