qemu/hw/tpm/tpm_passthrough.c
/*
 * Unless path or file descriptor set has been provided by user,
 * determine the sysfs cancel file following kernel documentation
 * in Documentation/ABI/stable/sysfs-class-tpm.
 * From /dev/tpm0 create /sys/class/tpm/tpm0/device/cancel
 * before 4.0: /sys/class/misc/tpm0/device/cancel
 */
Unless path or file descriptor set has been provided by user,
determine the sysfs cancel file following kernel documentation
in Documentation/ABI/stable/sysfs-class-tpm.
Unless path or file descriptor set has been provided by user determine the sysfs cancel file following kernel documentation in Documentation / ABI / stable / sysfs - class - tpm .
static int tpm_passthrough_open_sysfs_cancel(TPMPassthruState *tpm_pt)
{
    int fd = -1;
    char *dev;
    char path[PATH_MAX];
    if (tpm_pt->options->cancel_path) {
        fd = qemu_open(tpm_pt->options->cancel_path, O_WRONLY);
        if (fd < 0) {
            error_report("tpm_passthrough: Could not open TPM cancel path: %s",
                         strerror(errno));
        }
        return fd;
    }
    dev = strrchr(tpm_pt->tpm_dev, '/');
    if (!dev) {
        error_report("tpm_passthrough: Bad TPM device path %s",
                     tpm_pt->tpm_dev);
        return -1;
    }
    dev++;
    if (snprintf(path, sizeof(path), "/sys/class/tpm/%s/device/cancel",
                 dev) < sizeof(path)) {
        fd = qemu_open(path, O_WRONLY);
        if (fd < 0) {
            if (snprintf(path, sizeof(path), "/sys/class/misc/%s/device/cancel",
                         dev) < sizeof(path)) {
                fd = qemu_open(path, O_WRONLY);
            }
        }
    }
    if (fd < 0) {
        error_report("tpm_passthrough: Could not guess TPM cancel path");
    } else {
        tpm_pt->options->cancel_path = g_strdup(path);
    }
    return fd;
}
static int tpm_passthrough_open_sysfs_cancel ( TPMPassthruState * tpm_pt ) { int fd = -1 ; char * dev ; char path [ PATH_MAX ] ; if ( tpm_pt -> options -> cancel_path ) { fd = qemu_open ( tpm_pt -> options -> cancel_path , O_WRONLY ) ; if ( fd < 0 ) { error_report ( " " , strerror ( errno ) ) ; } return fd ; } dev = strrchr ( tpm_pt -> tpm_dev , ' ' ) ; if ( ! dev ) { error_report ( " " , tpm_pt -> tpm_dev ) ; return -1 ; } dev ++ ; if ( snprintf ( path , sizeof ( path ) , " " , dev ) < sizeof ( path ) ) { fd = qemu_open ( path , O_WRONLY ) ; if ( fd < 0 ) { if ( snprintf ( path , sizeof ( path ) , " " , dev ) < sizeof ( path ) ) { fd = qemu_open ( path , O_WRONLY ) ; } } } if ( fd < 0 ) { error_report ( " " ) ; } else { tpm_pt -> options -> cancel_path = g_strdup ( path ) ; } return fd ; }
Unless path or file descriptor set has been provided by user,
 determine the sysfs cancel file following kernel documentation
 in Documentation/ABI/stable/sysfs-class-tpm.
Unless path or file descriptor set has been provided by user determine the sysfs cancel file following kernel documentation in Documentation / ABI / stable / sysfs - class - tpm .