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.
>
>> /*
>> * For now we handle at most 16 double words as this is what the s390 base
>> * kernel handles and stores in the prefix page. If we ever need to go beyond
>> @@ -481,7 +476,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>> break;
>> case KVM_CAP_S390_HPAGE_1M:
>> r = 0;
>> - if (hpage && !kvm_is_ucontrol(kvm))
>> + if (!kvm_is_ucontrol(kvm))
>> r = 1;
>> break;
>> case KVM_CAP_S390_MEM_OP:
>> @@ -691,7 +686,7 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
>> mutex_lock(&kvm->lock);
>> if (kvm->created_vcpus)
>> r = -EBUSY;
>> - else if (!hpage || kvm->arch.use_cmma || kvm_is_ucontrol(kvm))
>> + else if (kvm->arch.use_cmma || kvm_is_ucontrol(kvm))
>> r = -EINVAL;
>> else {
>> r = 0;
>> @@ -4196,11 +4191,6 @@ static int __init kvm_s390_init(void)
>> return -ENODEV;
>> }
>>
>> - if (nested && hpage) {
>> - pr_info("nested (vSIE) and hpage (huge page backing) can currently not be activated concurrently");
>> - return -EINVAL;
>> - }
>> -
>> for (i = 0; i < 16; i++)
>> kvm_s390_fac_base[i] |=
>> S390_lowcore.stfle_fac_list[i] & nonhyp_mask(i);
>> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
>> index 8d5ce51637eb..928cb5818a21 100644
>> --- a/arch/s390/mm/gmap.c
>> +++ b/arch/s390/mm/gmap.c
>> @@ -1830,7 +1830,6 @@ struct gmap *gmap_shadow(struct gmap *parent, unsigned long asce,
>> unsigned long limit;
>> int rc;
>>
>> - BUG_ON(parent->mm->context.allow_gmap_hpage_1m);
>> BUG_ON(gmap_is_shadow(parent));
>> spin_lock(&parent->shadow_lock);
>> sg = gmap_find_shadow(parent, asce, edat_level);
>>
>
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