Re: [Qemu-devel] [Qemu-ppc] [PATCH v3 0/4] target-ppc: Add FWNMI support in qemu for powerKVM guests

[David Gibson]

On Thu, Apr 02, 2015 at 03:28:11PM +1100, Alexey Kardashevskiy wrote:
> On 11/19/2014 04:48 PM, Aravinda Prasad wrote:
> >
> >
> >On Tuesday 11 November 2014 08:54 AM, David Gibson wrote:
> >
> >[..]
> >
> >>
> >>So, this may not still be possible depending on whether the KVM side
> >>of this is already merged, but it occurs to me that there's a simpler
> >>way.
> >>
> >>Rather than mucking about with having to update the hypervisor on the
> >>RTAS location, they have qemu copy the code out of RTAS, patch it and
> >>copy it back into the vector, you could instead do this:
> >>
> >>   1. Make KVM instead of immediately delivering a 0x200 for a guest
> >>machine check, cause a special exit to qemu.
> >>
> >>   2. Have the register-nmi RTAS call store the guest side MC handler
> >>address in the spapr structure, but perform no actual guest code
> >>patching.
> >>
> >>   3. Allocate the error log buffer independently from the RTAS blob,
> >>so qemu always knows where it is.
> >>
> >>   4. When qemu gets the MC exit condition, instead of going via a
> >>patched 0x200 vector, just directly set the guest register state and
> >>jump straight into the guest side MC handler.
> >>
> >
> >Before I proceed further I would like to know what others think about
> >the approach proposed above (except for step 3 - as per PAPR the error
> >log buffer should be part of RTAS blob and hence we cannot have error
> >log buffer independent of RTAS blob).
> >
> >Alex, Alexey, Ben: Any thoughts?
> 
> 
> Any updates about FWNMI? Thanks

Huh.. I'd completely forgotten about this.  Aravinda, can you repost
your latest work on this?

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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