Re: [PATCH 06/11] KVM: s390: Multiple Epoch Facility support

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 28 Aug 2017 13:36:24 +0200
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 08/28/2017 01:21 PM, Cornelia Huck wrote:
> > On Mon, 28 Aug 2017 10:07:29 +0200
> > Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> >   
> >> From: "Collin L. Walling" <walling@linux.vnet.ibm.com>
> >>
> >> Allow for the enablement of MEF and the support for the extended
> >> epoch in SIE and VSIE for the extended guest TOD-Clock.
> >>
> >> A new interface is used for getting/setting a guest's extended
> >> TOD-Clock that uses a single ioctl invocation, KVM_S390_VM_TOD_EXT.
> >> The old method of getting and setting the guest TOD-Clock is
> >> retained and is used when the old ioctls are called.
> >>
> >> Signed-off-by: Collin L. Walling <walling@linux.vnet.ibm.com>
> >> Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
> >> Reviewed-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com>
> >> Reviewed-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>
> >> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> >> ---
> >>  Documentation/virtual/kvm/devices/vm.txt |  14 ++++-
> >>  arch/s390/include/asm/kvm_host.h         |   6 +-
> >>  arch/s390/include/uapi/asm/kvm.h         |   6 ++
> >>  arch/s390/kvm/kvm-s390.c                 | 101 +++++++++++++++++++++++++++++++
> >>  arch/s390/kvm/kvm-s390.h                 |   2 +
> >>  arch/s390/kvm/vsie.c                     |  10 +++
> >>  arch/s390/tools/gen_facilities.c         |   1 +
> >>  7 files changed, 138 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/Documentation/virtual/kvm/devices/vm.txt b/Documentation/virtual/kvm/devices/vm.txt
> >> index 903fc92..8a86778 100644
> >> --- a/Documentation/virtual/kvm/devices/vm.txt
> >> +++ b/Documentation/virtual/kvm/devices/vm.txt
> >> @@ -176,7 +176,8 @@ Architectures: s390
> >>  
> >>  3.1. ATTRIBUTE: KVM_S390_VM_TOD_HIGH
> >>  
> >> -Allows user space to set/get the TOD clock extension (u8).
> >> +Allows user space to set/get the TOD clock extension (u8). (superseded by  
> > 
> > s/(u8)./(u8)/  
> 
> ok
> 
> >   
> >> +KVM_S390_VM_TOD_EXT).
> >>  
> >>  Parameters: address of a buffer in user space to store the data (u8) to
> >>  Returns:    -EFAULT if the given address is not accessible from kernel space
> >> @@ -190,6 +191,17 @@ the POP (u64).
> >>  Parameters: address of a buffer in user space to store the data (u64) to
> >>  Returns:    -EFAULT if the given address is not accessible from kernel space
> >>  
> >> +3.3. ATTRIBUTE: KVM_S390_VM_TOD_EXT
> >> +
> >> +Allows user space to set/get bits 0-63 of the TOD clock register as defined in
> >> +the POP (u64), as well as the TOD clock extension (u8) if supported by the
> >> +host.  
> > 
> > I would be a bit more explicit on what happens if the tod clock
> > extension is not supported. What about:
> > 
> > "Allows user space to set/get bits 0-63 of the TOD clock register as
> > defined in the POP (u64). If the host supports the TOD clock extension
> > (u8), it also allows user space to set it. If the host does not support
> > it, it is stored as 0 and not allowed to be set to a value != 0."  
> 
> We check test_kvm_facility(kvm, 139))
> so what about using your text with the following change,
> 
> "host" --> "guest cpu model" ?

Fine with me.