On 04.11.2021 01:25, Sean Christopherson wrote:
Allocate the "new" memslot for !DELETE memslot updates straight away instead of filling an intermediate on-stack object and forcing kvm_set_memslot() to juggle the allocation and do weird things like reuse the old memslot object in MOVE. In the MOVE case, this results in an "extra" memslot allocation due to allocating both the "new" slot and the "invalid" slot, but that's a temporary and not-huge allocation, and MOVE is a relatively rare memslot operation. Regarding MOVE, drop the open-coded management of the gfn tree with a call to kvm_replace_memslot(), which already handles the case where new->base_gfn != old->base_gfn. This is made possible by virtue of not having to copy the "new" memslot data after erasing the old memslot from the gfn tree. Using kvm_replace_memslot(), and more specifically not reusing the old memslot, means the MOVE case now does hva tree and hash list updates, but that's a small price to pay for simplifying the code and making MOVE align with all the other flavors of updates. The "extra" updates are firmly in the noise from a performance perspective, e.g. the "move (in)active area" selfttests show a (very, very) slight improvement. Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx> For a new patch set version when the "main" commit is rewritten anyway (I mean the one titled "Keep memslots in tree-based structures instead of array-based ones") it makes sense to integrate changes like these into such modified main commit. This way a full algorithm / logic check for all the supported memslot operations needs to be done only once instead of having to be done multiple times for all these intermediate forms of the code (as this is a quite time-consuming job to do properly). I think it only makes sense to separate non-functional changes (like renaming of variables, comment rewording, open-coding a helper, etc.) into their own patches for ease of reviewing. Or if the main commit was unchanged from the last reviewed version so actual changes in the new version will stand out. Thanks, Maciej
