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Peter Anvin" , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Jonathan Corbet , Shuah Khan , Shuah Khan , Vishal Annapurve , Andrew Morton , Chris Li , Kairui Song , Kemeng Shi , Nhat Pham , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Youngjun Park , Qi Zheng , Shakeel Butt , Kiryl Shutsemau , Baoquan He , Jason Gunthorpe , John Hubbard , Peter Xu , Vlastimil Babka Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev References: <20260728-gmem-inplace-conversion-v9-0-35f9aec2aed2@google.com> <20260728-gmem-inplace-conversion-v9-7-35f9aec2aed2@google.com> <60d19013-d6d7-4eec-827a-2622e22cec98@intel.com> Content-Language: en-US From: Xiaoyao Li In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 7/31/2026 4:42 AM, Ackerley Tng wrote: > Xiaoyao Li writes: > >> On 7/29/2026 8:35 AM, Ackerley Tng via B4 Relay wrote: >>> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c >>> index 33c9830190e2e..89cf922232920 100644 >>> --- a/virt/kvm/guest_memfd.c >>> +++ b/virt/kvm/guest_memfd.c >>> @@ -893,6 +893,27 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, >>> EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_gmem_get_pfn); >>> >>> #ifdef CONFIG_HAVE_KVM_ARCH_GMEM_POPULATE >>> +static bool kvm_range_is_private(struct file *file, pgoff_t index, >>> + size_t nr_pages, struct kvm *kvm, gfn_t gfn) >>> +{ >>> + struct inode *inode = file_inode(file); >>> + pgoff_t last = index + nr_pages - 1; >>> + struct maple_tree *mt; >>> + void *entry; >>> + >>> + if (!gmem_in_place_conversion) >>> + return kvm_range_has_vm_memory_attributes(kvm, gfn, gfn + nr_pages, >>> + KVM_MEMORY_ATTRIBUTE_PRIVATE, >>> + KVM_MEMORY_ATTRIBUTE_PRIVATE); >>> + >>> + mt = &GMEM_I(inode)->attributes; >>> + mt_for_each(mt, entry, index, last) { >>> + if (kvm_gmem_interpret_entry(inode, entry) != >>> + KVM_MEMORY_ATTRIBUTE_PRIVATE) >>> + return false; >>> + } >>> + return true; >>> +} >>> >>> static long __kvm_gmem_populate(struct kvm *kvm, struct kvm_memory_slot *slot, >>> struct file *file, gfn_t gfn, struct page *src_page, >>> @@ -913,9 +934,7 @@ static long __kvm_gmem_populate(struct kvm *kvm, struct kvm_memory_slot *slot, >>> >>> folio_unlock(folio); >>> >>> - if (!kvm_range_has_vm_memory_attributes(kvm, gfn, gfn + 1, >>> - KVM_MEMORY_ATTRIBUTE_PRIVATE, >>> - KVM_MEMORY_ATTRIBUTE_PRIVATE)) { >>> + if (!kvm_range_is_private(file, index, 1, kvm, gfn)) { >> >> It's checking if a single gfn is private. >> > > But with huge page support we'd need to check a range of gfns... I guess > there's the argument of not keeping complexity for the future, but in > this case it's undoing functionality for this series and probably adding > it back later. let's leave the work for huge page support in the future. >> We can just use kvm_mem_is_private()? And it seems can be a separate patch. >> > > Do you mean that this refactoring could be a separate patch? I could > refactor out kvm_range_is_private() in a separate patch, then put in the > mt_for_each() check in this patch together as part of all the rest of > the "wiring". > > I considered that but it seemed like the refactoring was too small to > separate out into another patch when the mt_for_each() part is going to > be in this patch anyway. > > Or, I could add an earlier patch to first replace the call to > kvm_range_has_vm_memory_attributes() with a call to check just 1 gfn, > then this wiring patch would be simpler. > This is what I meant. An earlier patch to just replace kvm_range_has_vm_memory_attributes() with kvm_mem_is_private(). Then we can drop this 'big' diff in this patch. If kvm_range_is_private() is useful/required by huge page support, then let the huge page series to introduce it. It has nothing to do with the in-place conversion series. > Let me know what y'all think is best. Thanks! > >>> ret = -EINVAL; >>> goto out_put_folio; >>> }