Re: [PATCH RFCv3 4/9] s390x: prepare for more diag500 hypercalls

[Christian Borntraeger]

On 27.07.20 11:42, Cornelia Huck wrote:
> On Fri, 24 Jul 2020 16:37:45 +0200
> David Hildenbrand <david@redhat.com> wrote:
> 
>> Let's generalize, abstacting the virtio bits. diag500 is now a generic
>> hypercall to handle QEMU/KVM specific things. Explicitly specify all
>> already defined subcodes, including legacy ones (so we know what we can
>> use for new hypercalls). While at it, move exception handling into the
>> handler.
> 
> IIRC, diag 500 had been reserved as "KVM stuff" and not just "virtio
> stuff", so that should be fine.
> 
> The kernel documentation explicitly talks about "KVM virtio functions",
> though; you may want to tweak this (and also add a reference to any new
> subcodes.)
> 
> [Do we have a good resting place for documenting non-virtio-specific
> subcodes?]
> 


We have reserved 500-507 for KVM and 500 is marked as "KVM hypervisor call".
As 501 was gdb breakpoint, you could use 502,503 or just a new subcode
for 500.