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Andrew Cooper
a2ed643ed7
Issuing an IBPB command flushes the Branch Target Buffer, so that any poison left by one vcpu won't remain when beginning to execute the next. The cost of IBPB is substantial, and skipped on transition to idle, as Xen's idle code is robust already. All transitions into vcpu context are fully serialising in practice (and under consideration for being retroactively declared architecturally serialising), so a cunning attacker cannot use SP1 to try and skip the flush. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Jan Beulich <jbeulich@suse.com>
xen-bugtool =========== The xen-bugtool command line application will collate the Xen dmesg output, details of the hardware configuration of your machine, information about the build of Xen that you are using, plus, if you allow it, various logs. The information collated can either be posted to a Xen Bugzilla bug (this bug must already exist in the system, and you must be a registered user there), or it can be saved as a .tar.bz2 for sending or archiving. The collated logs may contain private information, and if you are at all worried about that, you should not use this tool, or you should explicitly exclude those logs from the archive. xen-bugtool is wholly interactive, so simply run it, and answer the questions.