From 0f22af940dc8ec4f437189096a5f8677995323b0 Mon Sep 17 00:00:00 2001 From: David Matlack Date: Wed, 4 Aug 2021 22:28:39 +0000 Subject: [PATCH] KVM: Move last_used_slot logic out of search_memslots Make search_memslots unconditionally search all memslots and move the last_used_slot logic up one level to __gfn_to_memslot. This is in preparation for introducing a per-vCPU last_used_slot. As part of this change convert existing callers of search_memslots to __gfn_to_memslot to avoid making any functional changes. Signed-off-by: David Matlack Message-Id: <20210804222844.1419481-3-dmatlack@google.com> Signed-off-by: Paolo Bonzini --- arch/powerpc/kvm/book3s_64_vio.c | 2 +- arch/powerpc/kvm/book3s_64_vio_hv.c | 2 +- include/linux/kvm_host.h | 64 +++++++++++++++++++++-------- 3 files changed, 50 insertions(+), 18 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c index 8da93fdfa59e..6365087f3160 100644 --- a/arch/powerpc/kvm/book3s_64_vio.c +++ b/arch/powerpc/kvm/book3s_64_vio.c @@ -346,7 +346,7 @@ static long kvmppc_tce_to_ua(struct kvm *kvm, unsigned long tce, unsigned long gfn = tce >> PAGE_SHIFT; struct kvm_memory_slot *memslot; - memslot = search_memslots(kvm_memslots(kvm), gfn); + memslot = __gfn_to_memslot(kvm_memslots(kvm), gfn); if (!memslot) return -EINVAL; diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index dc6591548f0c..f38dfe195ef2 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -80,7 +80,7 @@ static long kvmppc_rm_tce_to_ua(struct kvm *kvm, unsigned long gfn = tce >> PAGE_SHIFT; struct kvm_memory_slot *memslot; - memslot = search_memslots(kvm_memslots_raw(kvm), gfn); + memslot = __gfn_to_memslot(kvm_memslots_raw(kvm), gfn); if (!memslot) return -EINVAL; diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index bdfd5ed539c9..f30b53a07917 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1189,29 +1189,43 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id); bool kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args); /* - * search_memslots() and __gfn_to_memslot() are here because they are - * used in non-modular code in arch/powerpc/kvm/book3s_hv_rm_mmu.c. - * gfn_to_memslot() itself isn't here as an inline because that would - * bloat other code too much. + * Returns a pointer to the memslot at slot_index if it contains gfn. + * Otherwise returns NULL. + */ +static inline struct kvm_memory_slot * +try_get_memslot(struct kvm_memslots *slots, int slot_index, gfn_t gfn) +{ + struct kvm_memory_slot *slot; + + if (slot_index < 0 || slot_index >= slots->used_slots) + return NULL; + + slot = &slots->memslots[slot_index]; + + if (gfn >= slot->base_gfn && gfn < slot->base_gfn + slot->npages) + return slot; + else + return NULL; +} + +/* + * Returns a pointer to the memslot that contains gfn and records the index of + * the slot in index. Otherwise returns NULL. * * IMPORTANT: Slots are sorted from highest GFN to lowest GFN! */ static inline struct kvm_memory_slot * -search_memslots(struct kvm_memslots *slots, gfn_t gfn) +search_memslots(struct kvm_memslots *slots, gfn_t gfn, int *index) { int start = 0, end = slots->used_slots; - int slot = atomic_read(&slots->last_used_slot); struct kvm_memory_slot *memslots = slots->memslots; + struct kvm_memory_slot *slot; if (unlikely(!slots->used_slots)) return NULL; - if (gfn >= memslots[slot].base_gfn && - gfn < memslots[slot].base_gfn + memslots[slot].npages) - return &memslots[slot]; - while (start < end) { - slot = start + (end - start) / 2; + int slot = start + (end - start) / 2; if (gfn >= memslots[slot].base_gfn) end = slot; @@ -1219,19 +1233,37 @@ search_memslots(struct kvm_memslots *slots, gfn_t gfn) start = slot + 1; } - if (start < slots->used_slots && gfn >= memslots[start].base_gfn && - gfn < memslots[start].base_gfn + memslots[start].npages) { - atomic_set(&slots->last_used_slot, start); - return &memslots[start]; + slot = try_get_memslot(slots, start, gfn); + if (slot) { + *index = start; + return slot; } return NULL; } +/* + * __gfn_to_memslot() and its descendants are here because it is called from + * non-modular code in arch/powerpc/kvm/book3s_64_vio{,_hv}.c. gfn_to_memslot() + * itself isn't here as an inline because that would bloat other code too much. + */ static inline struct kvm_memory_slot * __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn) { - return search_memslots(slots, gfn); + struct kvm_memory_slot *slot; + int slot_index = atomic_read(&slots->last_used_slot); + + slot = try_get_memslot(slots, slot_index, gfn); + if (slot) + return slot; + + slot = search_memslots(slots, gfn, &slot_index); + if (slot) { + atomic_set(&slots->last_used_slot, slot_index); + return slot; + } + + return NULL; } static inline unsigned long -- 2.25.1