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Julien Grall
c8f62a0bb2
Xen does not properly support big.LITTLE platform. All vCPUs of a guest will always have the MIDR of the boot CPU (see arch_domain_create). At best the guest may see unreliable performance (vCPU switching between big and LITTLE), at worst the guest will become unreliable or insecure. This is becoming more apparent with branch predictor hardening in Linux because they target a specific kind of CPUs and may not work on other CPUs. For the time being, park any CPUs with a MDIR different from the boot CPU. This will be revisited in the future once Xen gains understanding of big.LITTLE. [1] https://lists.xenproject.org/archives/html/xen-devel/2016-12/msg00826.html Signed-off-by: Julien Grall <julien.grall@arm.com> Reviewed-by: Oleksandr Tyshchenkko <oleksandr_tyshchenko@epam.com> Reviewed-by: Stefano Stabellini <sstabellini@kernel.org> Acked-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.