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Re: [Xen-ia64-devel] [PATCH] Strange problem with virtual aliases

To: xen-ia64-devel <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-ia64-devel] [PATCH] Strange problem with virtual aliases
From: Matthew Chapman <matthewc@xxxxxxxxxxxxxxx>
Date: Thu, 30 Nov 2006 15:17:57 +1100
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I found the problem...

The real VHPT insertion is done based on the machine PTE returned from
translate_domain_pte, which does the appropriate offset calculations.

However, the insertion into the one-entry TLB uses the original PTE, but
the page size has been reset to PAGE_SIZE [1].  Thus the entry in the
one-entry TLB incorrectly maps the PAGE_SIZE sub-page which was faulted
on to the PAGE_SIZE sub-page at the bottom of the superpage.

I think it makes most sense to simply use the original itir when
inserting into the single-entry TLB, as per attached patch.  I've moved
the vcpu_set_tr_entry calls up a level into vcpu_itc_d and vcpu_itc_i;
the third caller previously used the 4 flag to specify "don't do that".

Matt

[1] In fact, this is enforced twice, once in translate_domain_pte and
again in vcpu_itc_no_srlz.

Attachment: tlb-insert.diff
Description: Text document

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