[libvirt] libvirt? qemu change that mmaps ELF files breaks libvirt svirt handling for os.kernel

Stefano, Paolo, I have an interesting fail in QEMU 2019-10-04T12:00:32.675188Z qemu-system-s390x: GLib: g_mapped_file_unref: assertion 'file != NULL' failed that bisected to commit 816b9fe450220e19acb91a0ce4a8ade7000648d1 (refs/bisect/bad) elf-ops.h: Map into memory the ELF to load strace tells that I can read the ELF file, but not mmap strace: 214365 openat(AT_FDCWD, "/var/lib/libvirt/images/test_cpu_timer.elf", O_RDONLY) = 36 214365 read(46, "\177ELF\2\2\1\0\0\0\0\0\0\0\0\0", 16) = 16 214365 lseek(46, 0, SEEK_SET) = 0 [...] 214365 fstat(46, {st_mode=S_IFREG|0755, st_size=168176, ...}) = 0 214365 mmap(NULL, 168176, PROT_READ|PROT_WRITE, MAP_PRIVATE, 46, 0) = -1 EACCES (Permission denied) So reading from /var/lib/libvirt/images/test_cpu_timer.elf does work, mmaping does not. setenforce 0 makes the problem go away. This might be more of an issue in libvirt, setting the svirt context too restrictive, but I am not too deep into the svirt part of libvirt. Reverting the qemu commit makes the problem go away.