[Xen-devel] [RFC 15/23] xen/balloon: Don't rely on the page granularity is the same for Xen and Linux
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From: David Vrabel <hidden>
Date: 2015-05-19 15:23:14
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On 14/05/15 18:00, Julien Grall wrote:
For ARM64 guests, Linux is able to support either 64K or 4K page granularity. Although, the hypercall interface is always based on 4K page granularity. With 64K page granuliarty, a single page will be spread over multiple Xen frame. When a driver request/free a balloon page, the balloon driver will have to split the Linux page in 4K chunk before asking Xen to add/remove the frame from the guest. Note that this can work on any page granularity assuming it's a multiple of 4K.
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quoted hunk ↗ jump to hunk
--- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c@@ -91,7 +91,7 @@ struct balloon_stats balloon_stats; EXPORT_SYMBOL_GPL(balloon_stats); /* We increase/decrease in batches which fit in a page */ -static xen_pfn_t frame_list[PAGE_SIZE / sizeof(unsigned long)]; +static xen_pfn_t frame_list[XEN_PAGE_SIZE / sizeof(unsigned long)];
PAGE_SIZE is appropriate here, since this is a guest-side array.
+ if (!(i % XEN_PFN_PER_PAGE)) {Ick. Can you refactor this into a loop per page calling a function that loops per MFN. Also similar tests elsewhere. David