On 09/19/2018 11:50 AM, Janosch Frank wrote: > On 9/19/18 10:56 AM, David Hildenbrand wrote: >> Am 19.09.18 um 10:48 schrieb Janosch Frank: >>> Now that we have VSIE support for VMs with huge memory backing, let's >>> make both features usable at the same time. >>> >>> Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx> >>> --- >>> Documentation/virtual/kvm/api.txt | 7 +++---- >>> arch/s390/kvm/kvm-s390.c | 14 ++------------ >>> arch/s390/mm/gmap.c | 1 - >>> 3 files changed, 5 insertions(+), 17 deletions(-) >>> >>> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt >>> index 8d8a372c8340..9ec6d23f41d5 100644 >>> --- a/Documentation/virtual/kvm/api.txt >>> +++ b/Documentation/virtual/kvm/api.txt >>> @@ -4509,15 +4509,14 @@ Do not enable KVM_FEATURE_PV_UNHALT if you disable HLT exits. >>> >>> Architectures: s390 >>> Parameters: none >>> -Returns: 0 on success, -EINVAL if hpage module parameter was not set >>> - or cmma is enabled, or the VM has the KVM_VM_S390_UCONTROL >>> +Returns: 0 on success, -EINVAL if cmma is enabled, or the VM has the KVM_VM_S390_UCONTROL >>> flag set >>> >>> With this capability the KVM support for memory backing with 1m pages >>> through hugetlbfs can be enabled for a VM. After the capability is >>> enabled, cmma can't be enabled anymore and pfmfi and the storage key >>> -interpretation are disabled. If cmma has already been enabled or the >>> -hpage module parameter is not set to 1, -EINVAL is returned. >>> +interpretation are disabled. If cmma has already been enabled, -EINVAL >>> +is returned. >>> >>> While it is generally possible to create a huge page backed VM without >>> this capability, the VM will not be able to run. >>> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c >>> index ac5da6b0b862..59f53b7c72d6 100644 >>> --- a/arch/s390/kvm/kvm-s390.c >>> +++ b/arch/s390/kvm/kvm-s390.c >>> @@ -172,11 +172,6 @@ static int nested; >>> module_param(nested, int, S_IRUGO); >>> MODULE_PARM_DESC(nested, "Nested virtualization support"); >>> >>> -/* allow 1m huge page guest backing, if !nested */ >>> -static int hpage; >>> -module_param(hpage, int, 0444); >>> -MODULE_PARM_DESC(hpage, "1m huge page backing support"); >>> - >> >> >> Do we want to keep the parameter for now? >> >> This would allow admins to disable it system-wide as long as it is in >> its early stage? (just like nested). We can allow co-existence, though. > > Both options are fine with me and considering the fixes needed for the > enablement this might be the better option. I think keeping the hpage parameter is fine, but we can consider changing the default to 1.
