Re: [PATCH 00/13] Nested Virtualization: Overview

[Christoph Egger <Christoph.Egger@amd.com>]

On Tuesday 30 November 2010 18:20:40 Bruce Edge wrote:
> On Fri, Nov 12, 2010 at 10:39 AM, Christoph Egger
> <Christoph.Egger@amd.com<mailto:Christoph.Egger@amd.com>> wrote:
>
> Hi!
>
> This patch series brings Nested Virtualization to Xen.
> This is the sixth patch series. Improvements to the
> previous patch submission:
>
> - Move GIF definition into SVM
> - Move VMEXIT emulation into SVM
> - Introduce hooks for getting host/guest cr3 for use with hap-on-hap
>   per proposal from Eddie Dong
> - Moved fields from struct nestedhvm into SVM
> - Renamed struct nestedhvm to struct nestedvcpu
> - Reworked VMRUN and VMEXIT emulation. It uses a defered emulation
>   mechanism that makes interrupt handling more efficient and is closer
>   to what VMX is doing
> - VMCB is peristent mapped. Only remap the VMCB when l1 guest
>   changes the address.
>
>
> 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 only on AMD.
> 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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>
> I'd like to ask a general question on nested virtualization. Can an L1 or
> L>1 VM span multiple physical machines?

I guess you mean virtual machines here. The answer is yes.

> I'm guessing not from the pdf, 
> http://lists.xensource.com/archives/html/xen-devel/2010-04/pdfsVHwQIeZLB.pd
>f, but I wanted to ask and confirm because if so, this would be a fantastic
> way to segregate individual customer infrastructures in a cloud
> environment.

I do not consider the patch series production stable but I would be glad when 
you can help with testing.

Christoph


-- 
---to satisfy European Law for business letters:
Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach b. Muenchen
Geschaeftsfuehrer: Alberto Bozzo, Andrew Bowd
Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen
Registergericht Muenchen, HRB Nr. 43632