docs: kvm: add documentation for KVM_CAP_S390_DIAG318

Documentation for the s390 DIAGNOSE 0x318 instruction handling.

Signed-off-by: Collin Walling <walling@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Link: https://lore.kernel.org/kvm/20200625150724.10021-2-walling@linux.ibm.com/
Message-Id: <20200625150724.10021-2-walling@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Collin Walling 2020-06-25 11:07:23 -04:00 committed by Christian Borntraeger
parent 37f66bbef0
commit f20d4e924b

View File

@ -6173,3 +6173,23 @@ specific interfaces must be consistent, i.e. if one says the feature
is supported, than the other should as well and vice versa. For arm64
see Documentation/virt/kvm/devices/vcpu.rst "KVM_ARM_VCPU_PVTIME_CTRL".
For x86 see Documentation/virt/kvm/msr.rst "MSR_KVM_STEAL_TIME".
8.25 KVM_CAP_S390_DIAG318
-------------------------
:Architectures: s390
This capability enables a guest to set information about its control program
(i.e. guest kernel type and version). The information is helpful during
system/firmware service events, providing additional data about the guest
environments running on the machine.
The information is associated with the DIAGNOSE 0x318 instruction, which sets
an 8-byte value consisting of a one-byte Control Program Name Code (CPNC) and
a 7-byte Control Program Version Code (CPVC). The CPNC determines what
environment the control program is running in (e.g. Linux, z/VM...), and the
CPVC is used for information specific to OS (e.g. Linux version, Linux
distribution...)
If this capability is available, then the CPNC and CPVC can be synchronized
between KVM and userspace via the sync regs mechanism (KVM_SYNC_DIAG318).