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From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Stefano Garzarella <sgarzare@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	Libvirt <libvir-list@redhat.com>,
	Marc Hartmayer <mhartmay@linux.ibm.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>
Subject: libvirt? qemu change that mmaps ELF files breaks libvirt svirt handling for os.kernel
Date: Fri, 4 Oct 2019 14:03:58 +0200	[thread overview]
Message-ID: <d450afbe-06ae-f6f7-3bc0-f1a54c31907c@de.ibm.com> (raw)

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.



             reply	other threads:[~2019-10-04 12:29 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-04 12:03 Christian Borntraeger [this message]
2019-10-04 12:13 ` libvirt? qemu change that mmaps ELF files breaks libvirt svirt handling for os.kernel Paolo Bonzini
2019-10-04 12:18   ` Christian Borntraeger
2019-10-04 12:36     ` Daniel P. Berrangé
2019-10-04 12:47       ` Christian Borntraeger
2019-10-04 16:41         ` Paolo Bonzini

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