On 10/27/23 10:03, Halil Pasic wrote:
On Fri, 27 Oct 2023 09:36:26 -0400
Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:
The interception handler for the PQAP(AQIC) command calls the
kvm_s390_gisc_register function to register the guest ISC with the channel
subsystem. If that call fails, the status response code 08 - indicating
Invalid ZONE/GISA designation - is returned to the guest. This response
code does not make sense because the non-zero return code from the
kvm_s390_gisc_register function can be due one of two things: Either the
ISC passed as a parameter by the guest to the PQAP(AQIC) command is greater
than the maximum ISC value allowed, or the guest is not using a GISA.
The "ISC passed as a parameter by the guest to the PQAP(AQIC) command is
greater than the maximum ISC value allowed" is not possible. The isc is
3 bits wide and all 8 values that can be represented on 3 bits are valid.
This is only possible if the hypervisor was to mess up, or if the machine
was broken.
kvm_s390_gisc_register(struct kvm *kvm, u32 gisc)
{
struct kvm_s390_gisa_interrupt *gi = &kvm->arch.gisa_int;
if (!gi->origin)
return -ENODEV;
if (gisc > MAX_ISC)
return -ERANGE;
...
Just quoting what is in the code.
Right! But it is not the guest that calls this function directly. This
function is called by the vfio_ap code.
The guest passes ISC in bits 61, 62 and 63 of GR1.
So the guest can't give you an invalid value.
Yes, I got it the first time you said that.
Regards,
Halil
