[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 0/5 v5] xen/arm: fix guest builder cache cohenrency (again, again)
George gave a release ack to v3. Both 32 and 64 bit have survived ~10,000 boots with v4. Changes in v5: avoid get_order_from_pages and just use 1<<MAX_ORDER s/sync_page_to_ram/flush_page_to_ram/g remove hard tab, add an emacs magic block Changes in v4: make sure to actually invalidate the cache, not just clean it rename existing cache flush functions to avoid catching me out that way again. switch to using a start + length in the domctl interface Changes in v3: s/cacheflush_page/sync_page_to_ram/ xc interface takes a length instead of an end make the domctl range inclusive. make xc interface internal -- it isn't needed from libxl in the current design and it is easier to expose an interface in the future than to hide it. Changes in v2: Flush on page alloc and do targeted flushes at domain build time rather than a big flush after domain build. This adds a new call to common code, which is stubbed out on x86. This avoid needing to worry about preemptability of the new domctl and also catches cases related to ballooning where things might not be flushed (e.g. a guest scrubs a page but doesn't clean the cache) This has done 12000 boot loops on arm32 and 10000 on arm64. Given the security aspect I would like to put this in 4.4. Original blurb: On ARM we need to take care of cache coherency for guests which we have just built because they start with their caches disabled. Our current strategy for dealing with this, which is to make guest memory default to cacheable regardless of the in guest configuration (the HCR.DC bit), is flawed because it doesn't handle guests which enable their MMU before enabling their caches, which at least FreeBSD does. (NB: Setting HCR.DC while the guest MMU is enabled is UNPREDICTABLE, hence we must disable it when the guest turns its MMU one). There is also a security aspect here since the current strategy means that a guest which enables its MMU before its caches can potentially see unscrubbed data in RAM (because the scrubbed bytes are still held in the cache). As well as the new stuff this series removes the HCR.DC support and performs two purely cosmetic renames. Ian. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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