Re: [Xen-devel] HYBRID: PV in HVM container

[Keir Fraser <keir.xen@xxxxxxxxx>]

On 27/06/2011 20:24, "Mukesh Rathor" <mukesh.rathor@xxxxxxxxxx> wrote:

> 
> Hi guys,
> 
> Cheers!! I got PV in HVM container prototype working with single VCPU
> (pinned to a cpu). Basically, I create a VMX container just like for
> HVM guest (with some differences that I'll share soon when I clean up
> the code). The PV guest starts in Protected mode with the usual
> entry point startup_xen().
> 
> 0. Guest kernel runs in ring 0, CS:0x10.
> 
> 1. I use xen for all pt management just like a PV guest. So at present
>    all faults are going to xen, and when fixup_page_fault() fails, they
>    are injected into the container for the guest to handle it.
> 
> 2. The guest manages the GDT, LDT, TR, in the container.
> 
> 3. The guest installs the trap table in the vmx container instead of
>    do_set_trap_table().

To be clear, you intend for this to work with unmodified PV guests, right?
All of this translation can easily be done in Xen, avoiding multiple paths
needed in the guest kernel (not really tenable for upstreaming).

 -- Keir

> 4. Events/INTs are delivered via HVMIRQ_callback_vector.
> 
> 5. MSR_GS_BASE is managed by the guest in the container itself.
> 
> 6. Currently, I'm managing cr4 in the container, but going to xen
>    for cr0. I need to revisit that.
> 
> 7. Currently, VPID is disabled, I need to figure it out, and revisit.
> 
> 8. Currently, VM_ENTRY_LOAD_GUEST_PAT is disabled, I need to look at
>    that. 
> 
> These are the salient points I can think of at the moment. Next, I am
> going to run LMBench and figure out the gains. After that, make sure
> SMP works, and things are stable, and look at any enhancements. I need
> to look at couple unrelated bugs at the moment, but hope to return back
> to this very soon.
> 
> thanks,
> Mukesh
> 
> 
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