General KVM huge page support on s390 has to be enabled via the kvm.hpage module parameter. Either nested or hpage can be enabled, as we currently do not support vSIE for huge backed guests. Once the vSIE support is added we will either drop the parameter or enable it as default. For a guest the feature has to be enabled through the new KVM_CAP_S390_HPAGE_1M capability and the hpage module parameter. Enabling it means that cmm can't be enabled for the vm and disables pfmf and storage key interpretation. This is due to the fact that in some cases, in upcoming patches, we have to split huge pages in the guest mapping to be able to set more granular memory protection on 4k pages. These split pages have fake page tables that are not visible to the Linux memory management which subsequently will not manage its PGSTEs, while the SIE will. Disabling these features lets us manage PGSTE data in a consistent matter and solve that problem.
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| @@ -949,6 +949,7 @@ struct kvm_ppc_resize_hpt { · 948 unmodified lines | ||
| 949 | 949 | #define KVM_CAP_GET_MSR_FEATURES 153 |
| 950 | 950 | #define KVM_CAP_HYPERV_EVENTFD 154 |
| 951 | 951 | #define KVM_CAP_HYPERV_TLBFLUSH 155 |
| 952 | +#define KVM_CAP_S390_HPAGE_1M 156 | |
| 952 | 953 | |
| 953 | 954 | #ifdef KVM_CAP_IRQ_ROUTING |
| 954 | 955 | |