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2017-12-20qemu-pr-helper: miscellaneous fixesPaolo Bonzini
1) Return a generic sense if TEST UNIT READY does not provide one; 2) Fix two mistakes in copying from the spec. Cc: qemu-stable@nongnu.org Reported-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-10-18qemu-pr-helper: use new libmultipath APIPaolo Bonzini
libmultipath has recently changed its API. The new API supports multi-threaded clients better. Unfortunately there is no backwards-compatibility, so we just switch to the new one. Running QEMU compiled with the new library on the old library will likely crash, while doing the opposite will cause QEMU not to start at all (because udev, get_multipath_config and put_multipath_config are undefined). Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-22scsi: add persistent reservation manager using qemu-pr-helperPaolo Bonzini
This adds a concrete subclass of pr-manager that talks to qemu-pr-helper. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-22scsi: add multipath support to qemu-pr-helperPaolo Bonzini
Proper support of persistent reservation for multipath devices requires communication with the multipath daemon, so that the reservation is registered and applied when a path comes up. The device mapper utilities provide a library to do so; this patch makes qemu-pr-helper.c detect multipath devices and, when one is found, delegate the operation to libmpathpersist. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-22scsi: build qemu-pr-helperPaolo Bonzini
Introduce a privileged helper to run persistent reservation commands. This lets virtual machines send persistent reservations without using CAP_SYS_RAWIO or out-of-tree patches. The helper uses Unix permissions and SCM_RIGHTS to restrict access to processes that can access its socket and prove that they have an open file descriptor for a raw SCSI device. The next patch will also correct the usage of persistent reservations with multipath devices. It would also be possible to support for Linux's IOC_PR_* ioctls in the future, to support NVMe devices. For now, however, only SCSI is supported. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-22scsi, file-posix: add support for persistent reservation managementPaolo Bonzini
It is a common requirement for virtual machine to send persistent reservations, but this currently requires either running QEMU with CAP_SYS_RAWIO, or using out-of-tree patches that let an unprivileged QEMU bypass Linux's filter on SG_IO commands. As an alternative mechanism, the next patches will introduce a privileged helper to run persistent reservation commands without expanding QEMU's attack surface unnecessarily. The helper is invoked through a "pr-manager" QOM object, to which file-posix.c passes SG_IO requests for PERSISTENT RESERVE OUT and PERSISTENT RESERVE IN commands. For example: $ qemu-system-x86_64 -device virtio-scsi \ -object pr-manager-helper,id=helper0,path=/var/run/qemu-pr-helper.sock -drive if=none,id=hd,driver=raw,file.filename=/dev/sdb,file.pr-manager=helper0 -device scsi-block,drive=hd or: $ qemu-system-x86_64 -device virtio-scsi \ -object pr-manager-helper,id=helper0,path=/var/run/qemu-pr-helper.sock -blockdev node-name=hd,driver=raw,file.driver=host_device,file.filename=/dev/sdb,file.pr-manager=helper0 -device scsi-block,drive=hd Multiple pr-manager implementations are conceivable and possible, though only one is implemented right now. For example, a pr-manager could: - talk directly to the multipath daemon from a privileged QEMU (i.e. QEMU links to libmpathpersist); this makes reservation work properly with multipath, but still requires CAP_SYS_RAWIO - use the Linux IOC_PR_* ioctls (they require CAP_SYS_ADMIN though) - more interestingly, implement reservations directly in QEMU through file system locks or a shared database (e.g. sqlite) Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-19scsi: move block/scsi.h to include/scsi/constants.hPaolo Bonzini
Complete the transition by renaming this header, which was shared by block/iscsi.c and the SCSI emulation code. Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-19scsi: introduce sg_io_sense_from_errnoPaolo Bonzini
Move more knowledge of SG_IO out of hw/scsi/scsi-generic.c, for reusability. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-19scsi: introduce scsi_build_sensePaolo Bonzini
Move more knowledge of sense data format out of hw/scsi/scsi-bus.c for reusability. Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-09-19scsi: move non-emulation specific code to scsi/Paolo Bonzini
util/scsi.c includes some SCSI code that is shared by block/iscsi.c and hw/scsi, but the introduction of the persistent reservation helper will add many more instances of this. There is also include/block/scsi.h, which actually is not part of the core block layer. The persistent reservation manager will also need a home. A scsi/ directory provides one for both the aforementioned shared code and the PR manager code. Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>