From: "Maciej S. Szmigiero" <[email protected]> Introduce a memslots gfn upper bound operation and use it to optimize kvm_zap_gfn_range(). This way this handler can do a quick lookup for intersecting gfns and won't have to do a linear scan of the whole memslot set.
Signed-off-by: Maciej S. Szmigiero <[email protected]> --- arch/x86/kvm/mmu/mmu.c | 41 ++++++++++++++++++++++++++++++++++++++-- include/linux/kvm_host.h | 22 +++++++++++++++++++++ 2 files changed, 61 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 74781c00a420..7e610d3bc819 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -5498,14 +5498,51 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end) int i; bool flush = false; + if (gfn_end == gfn_start || WARN_ON(gfn_end < gfn_start)) + return; + write_lock(&kvm->mmu_lock); for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { - int ctr; + int idxactive; + struct rb_node *node; slots = __kvm_memslots(kvm, i); - kvm_for_each_memslot(memslot, ctr, slots) { + idxactive = kvm_memslots_idx(slots); + + /* + * Find the slot with the lowest gfn that can possibly intersect with + * the range, so we'll ideally have slot start <= range start + */ + node = kvm_memslots_gfn_upper_bound(slots, gfn_start); + if (node) { + struct rb_node *pnode; + + /* + * A NULL previous node means that the very first slot + * already has a higher start gfn. + * In this case slot start > range start. + */ + pnode = rb_prev(node); + if (pnode) + node = pnode; + } else { + /* a NULL node below means no slots */ + node = rb_last(&slots->gfn_tree); + } + + for ( ; node; node = rb_next(node)) { gfn_t start, end; + memslot = container_of(node, struct kvm_memory_slot, + gfn_node[idxactive]); + + /* + * If this slot starts beyond or at the end of the range so does + * every next one + */ + if (memslot->base_gfn >= gfn_start + gfn_end) + break; + start = max(gfn_start, memslot->base_gfn); end = min(gfn_end, memslot->base_gfn + memslot->npages); if (start >= end) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index bb50776a5ebd..884cac86042a 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -703,6 +703,28 @@ struct kvm_memory_slot *id_to_memslot(struct kvm_memslots *slots, int id) return NULL; } +static inline +struct rb_node *kvm_memslots_gfn_upper_bound(struct kvm_memslots *slots, + gfn_t gfn) +{ + int idxactive = kvm_memslots_idx(slots); + struct rb_node *node, *result = NULL; + + for (node = slots->gfn_tree.rb_node; node; ) { + struct kvm_memory_slot *slot; + + slot = container_of(node, struct kvm_memory_slot, + gfn_node[idxactive]); + if (gfn < slot->base_gfn) { + result = node; + node = node->rb_left; + } else + node = node->rb_right; + } + + return result; +} + /* * KVM_SET_USER_MEMORY_REGION ioctl allows the following operations: * - create a new memory slot
