On Tue, Oct 27, 2026 at 02:56:03AM +0000, Kevin Loughlin wrote: > This series enables virtio-balloon free page reporting and memory balloon > inflation/deflation in Confidential Computing (CoCo) guests, starting > with architectural hooks implemented for AMD SEV variants, in order to > support dynamic CoCo guest resizing. > > Today, memory ballooning and free page reporting are essentially unusable > in CoCo guests due to three main roadblocks:
For me, the bigger question is not whether we can, but whether we should. Considerations I would like to see addressed: Security, e.g.: does knowing which memory is free leak information from the guest? If no, why not? Consider CONFIG_SHUFFLE_PAGE_ALLOCATOR, RANDSTRUCT, etc. correctness, e.g.: Linux has init on free (and default on windows), if initialized pages are dropped and host can not be trusted, they have to be re-initialized. Is this handled? I don't see it in code. Also, performance, e.g.: How much does this re-initialization cost? Management: it was simple with balloon off unconditionally. Now we are in murkier waters with various features offering various performance/security tradeoffs. What if some guests want the tradeoffs but others don't? Documentation: for all of the above. -- MST
