[PATCH 0/3] avoid unnecessary memslot rmap walks

From: Anthony Yznaga
Date: Tue Jun 02 2020 - 16:10:49 EST

While investigating optimizing qemu start time for large memory guests
I found that kvm_mmu_slot_apply_flags() is walking rmaps to update
existing sptes when creating or moving a slot but that there won't be
any existing sptes to update and any sptes inserted once the new memslot
is visible won't need updating. I can't find any reason for this not to
be the case, but I've taken a more cautious approach to fixing this by
dividing things into three patches.

Anthony Yznaga (3):
KVM: x86: remove unnecessary rmap walk of read-only memslots
KVM: x86: avoid unnecessary rmap walks when creating/moving slots
KVM: x86: minor code refactor and comments fixup around dirty logging

arch/x86/kvm/x86.c | 106 +++++++++++++++++++++++++----------------------------
1 file changed, 49 insertions(+), 57 deletions(-)