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[Xen-devel] Re: [PATCH 00/13] Nested Virtualization: Overview

To: Christoph Egger <Christoph.Egger@xxxxxxx>
Subject: [Xen-devel] Re: [PATCH 00/13] Nested Virtualization: Overview
From: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Date: Wed, 8 Sep 2010 16:22:43 +0100
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "Dong, Eddie" <eddie.dong@xxxxxxxxx>
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Christoph, I've posted separate comments on patches 5, 12 and 13.
Otherwise this series is looking OK to me -- provided that you and Eddie
can agree on how the common code is going to work.

Eddie - I don't think having a common vmexit interface _requires_ you to
do 17 VMREADs on every VMEXIT (and if it does, that needs to be
changed).  The SVM implementation may pull all the information out at
once but the VMX one could do it lazily.

Christoph, I asked before about whether we could lose the extra
namespace for exit reasons.  Looking at the way they're used, couldn't
we just pass around the native numbers and maybe some flags for which of
the ancillary fields are valid?



At 15:53 +0100 on 01 Sep (1283356406), Christoph Egger wrote:
> Hi!
> This patch series brings Nested Virtualization to Xen.
> This is the third patch series. Improvements to the
> previous patch submission:
> - Incorporated feedback discussion with Keir, Tim and Eddie.
> There might still be some nuances to fiddle with to make it
> fit for VMX. Feedback from Intel is appreciated, therefore.
> The patch series:
> patch 01: add nestedhvm guest config option to the tools.
>                   This is the only one patch touching the tools
> patch 02: Add data structures for nested virtualization.
> patch 03: add nestedhvm function hooks.
> patch 04: The heart of nested virtualization.
> patch 05: Allow switch to paged real mode during vmrun emulation.
>                   Emulate cr0 and cr4 when guest does not intercept them
>                   (i.e. Hyper-V/Windows7, KVM)
> patch 06: When injecting an exception into nested guest, inject
>                   #VMEXIT into the guest if intercepted.
> patch 07: Allow guest to enable SVM in EFER.
> patch 08: Handle interrupts (generic part).
> patch 09: SVM specific implementation for nested virtualization.
> patch 10: Handle interrupts (SVM specific).
> patch 11: The piece of code that effectively turns on nested virtualization.
> patch 12: Move dirty_vram from struct hvm_domain to struct p2m_domain.
>                   This change is the first part from a larger not-yet-ready
>                   change where the vram and log_dirty tracking is teached
>                   to work on per p2m.
> patch 13: Handle nested pagefault to enable hap-on-hap and handle
>                   nested guest page-table-walks to emulate instructions
>                   the guest does not intercept (i.e. WBINVD with Windows 7).
> -- 
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Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, XenServer Engineering
Citrix Systems UK Ltd.  (Company #02937203, SL9 0BG)

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