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Sampat wrote: >> >> >> On 11/27/25 11:40 AM, Kiryl Shutsemau wrote: >>> 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. >> >> If memory that hasn't been plugged yet never gets plugged in or is only >> partially plugged in, wouldn't we be wasting space by preallocating >> the bitmap upfront? Or would that not be a concern in favor of >> transparency? > > 4k per 64GiB of physical address space should be low enough to ignore, no? > > We can look into optimizing it out when it is an actual, not imaginary > problem. > Sure, that's fair! --Pratik