[no direct reply because gmane still breaks it] WBINVD or CLFLUSH is also needed to safely change caching attributes of pages that are already mapped. Since CLFLUSH is somewhat hard to use for this near all Linux kernels use WBINVD for this. Examples where this happens are ioremap() using PAT, AGP allocations, 3d drivers.
For the PCI-E case typically CLFLUSH can be used instead of WBINVD too (on CPUs that support it) but again it's harder to use. Another case where the kernel uses it is reboot but there you can likely ignore it. But might be hard to distingush from legitimate cases. If you allow uncached pages in guests it is probably not safe to nop completely (on SVM). You might be able to emulate it by doing CLFLUSH on all guest mappings or rather on all mappings that alias an uncached mapping. That might be even slower than wbinvd though, but should be at least potentially preemptible. -Andi ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
