Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Date | Wed, 1 Nov 2023 23:28:32 +0100 | Subject | Re: [PATCH v13 17/35] KVM: Add transparent hugepage support for dedicated guest memory | From | Paolo Bonzini <> |
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On 11/1/23 17:36, Sean Christopherson wrote: >>> "Allow" isn't perfect, e.g. I would much prefer a straight KVM_GUEST_MEMFD_USE_HUGEPAGES >>> or KVM_GUEST_MEMFD_HUGEPAGES flag, but I wanted the name to convey that KVM doesn't >>> (yet) guarantee hugepages. I.e. KVM_GUEST_MEMFD_ALLOW_HUGEPAGE is stronger than >>> a hint, but weaker than a requirement. And if/when KVM supports a dedicated memory >>> pool of some kind, then we can add KVM_GUEST_MEMFD_REQUIRE_HUGEPAGE. >> I think that the current patch is fine, but I will adjust it to always >> allow the flag, and to make the size check even if !CONFIG_TRANSPARENT_HUGEPAGE. >> If hugepages are not guaranteed, and (theoretically) you could have no >> hugepage at all in the result, it's okay to get this result even if THP is not >> available in the kernel. > Can you post a fixup patch? It's not clear to me exactly what behavior you intend > to end up with.
Sure, just this:
diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 7d1a33c2ad42..34fd070e03d9 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -430,10 +430,7 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args) { loff_t size = args->size; u64 flags = args->flags; - u64 valid_flags = 0; - - if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) - valid_flags |= KVM_GUEST_MEMFD_ALLOW_HUGEPAGE; + u64 valid_flags = KVM_GUEST_MEMFD_ALLOW_HUGEPAGE; if (flags & ~valid_flags) return -EINVAL; @@ -441,11 +438,9 @@ int kvm_gmem_create(struct kvm *kvm, struct kvm_create_guest_memfd *args) if (size < 0 || !PAGE_ALIGNED(size)) return -EINVAL; -#ifdef CONFIG_TRANSPARENT_HUGEPAGE if ((flags & KVM_GUEST_MEMFD_ALLOW_HUGEPAGE) && !IS_ALIGNED(size, HPAGE_PMD_SIZE)) return -EINVAL; -#endif return __kvm_gmem_create(kvm, size, flags); } Paolo
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