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| author | Paolo Bonzini <pbonzini@redhat.com> | 2017-08-21 18:58:56 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-09-22 01:06:51 +0200 |
| commit | 7c9e527659c67d4d7b41d9504f93d2d7ee482488 (patch) | |
| tree | 2f604a8ad523e8cf9217b464344900f86d0bbfba /scsi/trace-events | |
| parent | 092aa2fc65b7a35121616aad8f39d47b8f921618 (diff) | |
| download | qemu-7c9e527659c67d4d7b41d9504f93d2d7ee482488.tar.gz | |
scsi, file-posix: add support for persistent reservation management
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>
Diffstat (limited to 'scsi/trace-events')
| -rw-r--r-- | scsi/trace-events | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/scsi/trace-events b/scsi/trace-events new file mode 100644 index 0000000000..45f5b6e49b --- /dev/null +++ b/scsi/trace-events @@ -0,0 +1,3 @@ +# scsi/pr-manager.c +pr_manager_execute(int fd, int cmd, int sa, void *opaque) "fd=%d cmd=0x%02x service action=0x%02x opaque=%p" +pr_manager_run(int fd, int cmd, int sa) "fd=%d cmd=0x%02x service action=0x%02x" |