On Wed, 2024-03-13 at 12:55 -0700, Sean Christopherson wrote: > Nit, it's the head page, not the tail page. Strictly speaking, it's > probably both > (or neither, if you're a half glass empty person), but the buggy code > that is > processing regions is specifically dealing with what it calls the > head page. Yes, the buggy logic happens only when it is a head and a tail page. Even though the end part is the overflow. I'll update the verbiage. [snip] > > Also rename hugepage_has_attrs() to __slot_hugepage_has_attrs() > > because it > > is a delicate function that should not be widely used, and only is > > valid > > for ranges covered by the passed slot. > > Eh, I vote to drop the rename. It's (a) a local static, (b) guarded > by > CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES=y, (c) pretty obvious from the > @slot > param that it works on a single slot, (d) the double underscores > suggests > there is an outer wrapper with the same name, which there is not, and > (e) the > rename adds noise to a diff that's destined for stable@. Ok, I'll drop that part. As for non-stable bound cleanup I was also noticing: 1. lpage_info indices should be kvmallocs() as multiple page aligned vmallocs are wasteful for small memslots, and even normal sized ones at the 1GB level. 2. lpage_info doesn't need to keep track of unaligned heads and tails because the unaligned part can never be huge. lpage_info_slot() can skip checking the array based on the slot, GFN and page size which it already has. Allocating kvm_lpage_info's for those and then carefully making sure they are always disabled adds complexity (especially with KVM_LPAGE_MIXED_FLAG in the mix) and uses extra memory. Whether it's a tiny bit faster that a conditional in a helper, I don't know.
