Re: [PATCH v6 2/2] s390: diagnose 318 info reset and migration support

[Cornelia Huck]

On Tue, 28 Jan 2020 09:37:46 -0500
Collin Walling <address@hidden> wrote:

> On 1/27/20 12:35 PM, Cornelia Huck wrote:
> > On Mon, 27 Jan 2020 11:39:02 -0500
> > Collin Walling <address@hidden> wrote:
> >   
> >> On 1/27/20 6:47 AM, Cornelia Huck wrote:  
> >>> On Fri, 24 Jan 2020 17:14:04 -0500
> >>> Collin Walling <address@hidden> wrote:
> >>>     
> >>>> DIAGNOSE 0x318 (diag318) is a privileged s390x instruction that must
> >>>> be intercepted by SIE and handled via KVM. Let's introduce some
> >>>> functions to communicate between QEMU and KVM via ioctls. These
> >>>> will be used to get/set the diag318 information.    
> >>>
> >>> Do you want to give a hint what diag 318 actually does?
> >>>     
> >>
> >> For the sake of completeness, I'll have to get back to you on this.
> >>  
> 
> The DIAGNOSE 318 instruction allows the guest to store diagnostic data
> that is collected by the firmware in the case of hardware/firmware
> service events. The instruction is invoked in the Linux kernel and
> intercepted in KVM. QEMU needs to collect this data for migration
> so that this data is consistent on the destination host.
> 
> Perhaps I should add this to the patch description as well? :)

Yes, please :) It will make things easier for any unfortunate soul
wanting to find out what this is about in the future.