Anthony Liguori <[EMAIL PROTECTED]> wrote on 04/29/2008 05:32:09 PM:
Subject
[PATCH] Handle vma regions with no backing page
This patch allows VMA's that contain no backing page to be used for guest
memory. This is a drop-in replacement for Ben-Ami's first page in his direct
mmio series. Here, we continue to allow mmio pages to be represented in the
rmap.
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
{
- return pfn_to_page(gfn_to_pfn(kvm, gfn));
+ pfn_t pfn;
+
+ pfn = gfn_to_pfn(kvm, gfn);
+ if (pfn_valid(pfn))
+ return pfn_to_page(pfn);
+
+ return NULL;
}
We noticed that pfn_valid does not always works as expected by this patch
to indicate that a pfn has a backing page.
We have seen a case where CONFIG_NUMA was not set and then where pfn_valid
returned 1 for an mmio pfn.
We then changed the config file with CONFIG_NUMA set and it worked fine as
expected (since a different implementation of pfn_valid was used).
How should we overcome this issue?
Thanks,
Ben
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