Messages in this thread |  | | Date | Thu, 27 Nov 2025 17:40:24 +0000 | | From | Kiryl Shutsemau <> | | Subject | Re: [RFC PATCH 2/4] mm: Add support for unaccepted memory hotplug |
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On Wed, Nov 26, 2025 at 04:27:29PM -0600, Pratik R. Sampat wrote: > > > On 11/26/25 5:12 AM, Kiryl Shutsemau wrote: > > On Tue, Nov 25, 2025 at 11:57:51AM -0600, Pratik R. Sampat wrote: > >> The unaccepted memory structure currently only supports accepting memory > >> present at boot time. The unaccepted table uses a fixed-size bitmap > >> reserved in memblock based on the initial memory layout, preventing > >> dynamic addition of memory ranges after boot. This causes guest > >> termination when memory is hot-added in a secure virtual machine due to > >> accessing pages that have not transitioned to private before use. > > > > How does the hot-pluggable memory look in EFI memory map? I thought > > hot-pluggable ranges suppose to be declared thare. The cleanest solution > > would be to have hot-pluggable and unaccepted indicated in EFI memory, > > so we can size bitmap accordingly upfront. > > > > I'm not quite sure if I fully understand. Do you mean to refer to the > EFI_MEMORY_HOT_PLUGGABLE attribute that is used for cold plugged boot > memory? If so, wouldn't it still be desirable to increase the size of > the bitmap to what was marked as hotpluggable initially?
I just don't understand how hotpluggable memory presented in EFI memory map in presence of unaccepted memory. If not-yet-plugged memory marked as unaccepted we can preallocate bitmap upfront and make unaccepted memory transparent wrt hotplug.
BTW, isn't virtio-mem a more attractive target to support than HW-style hotplug?
-- Kiryl Shutsemau / Kirill A. Shutemov
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