On Fri, Mar 08, 2024 at 03:50:05PM +0000, Gowans, James wrote: > Currently when using anonymous memory for KVM guest RAM, the memory all > remains mapped into the kernel direct map. We are looking at options to > get KVM guest memory out of the kernel’s direct map as a principled > approach to mitigating speculative execution issues in the host kernel. > Our goal is to more completely address the class of issues whose leak > origin is categorized as "Mapped memory" [1]. One of the things that is holding Linux back is the inability to do I/O to memory which is not part of memmap. _So Much_ of our infrastructure is based on having a struct page available to stick into an sglist, bio, skb_frag, or whatever. The solution to this is to move to a (phys_addr, length) tuple instead of (page, offset, len) tuple. I call this "phyr" and I've written about it before. I'm not working on this as I have quite enough to do with the folio work, but I hope somebody works on it before I get time to.
