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

[David Gibson]

On Thu, Jul 02, 2015 at 07:11:52PM +1000, Alexey Kardashevskiy wrote:
> On 04/02/2015 03:46 PM, David Gibson wrote:
> >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?
> 
> 
> Aravinda disappeared...

Ok, well someone who cares about FWNMI is going to have to start
sending something, or it won't happen.

-- 
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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