On Wed, Nov 23, 2022 at 05:50:37PM -0800, Dan Williams wrote: > arch_add_memory() does not add memory to the page allocator. For > example, memremap_pages() uses arch_add_memory() and explicitly does not > release the memory to the page allocator. This check belongs in > add_memory_resource() to prevent new memory that violates TDX from being > onlined. Hopefully there is also an option to disable TDX from the > kernel boot command line to recover memory-hotplug without needing to > boot into the BIOS to toggle TDX. So I've been pushing for all this to either require: tdx=force on the cmdline to boot-time enable, or delay all the memory allocation to the first KVM/TDX instance being created. That is, by default, none of this crud should ever trigger and consume memory if you're not using TDX (most of us really). (every machine I have loads kvm.ko unconditionally -- even if I never user KVM, so kvm.ko load time is not a valid point in time to do TDX enablement).
