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Re: [Xen-devel] [PATCH] support 1gb pages in guest page table walker

To: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] support 1gb pages in guest page table walker
From: Christoph Egger <Christoph.Egger@xxxxxxx>
Date: Tue, 26 Jul 2011 14:11:41 +0200
Cc: Jan, "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, Beulich <JBeulich@xxxxxxxxxx>
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On 07/25/11 12:30, Tim Deegan wrote:
At 11:25 +0100 on 25 Jul (1311593146), Tim Deegan wrote:
Also this function should be called from the CPUID trap handler to make
sure we never advertise PSE1GB when we're not going to support it.

Er, not this function exactly, since CPUID should report the feature
even when the guest's not in long_mode.  I think it needs a
hvm_pse1G_supported that can be called from CPUID, and then
guest_supports_1G_superpages() boils down to
"(GUEST_PAGING_LEVEL>= 4)&&  hvm_pse1G_supported(v)"

New version attached. I removed the fake l1e calculation.
Something is still wrong: The l2 guest kernel crashes with
an unexpected null pointer derefencing but it boots w/o
this patch.

Is it a problem when l1 guest uses 1gb pages where the host
uses 4k or 2m pages?


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Attachment: xen_pagewalk.diff
Description: xen_pagewalk.diff

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