From c928bfc2632fa3dd6a3bd4504ac6d8e42302287a Mon Sep 17 00:00:00 2001 From: "Maciej S. Szmigiero" Date: Mon, 6 Dec 2021 20:54:25 +0100 Subject: [PATCH] KVM: Integrate gfn_to_memslot_approx() into search_memslots() s390 arch has gfn_to_memslot_approx() which is almost identical to search_memslots(), differing only in that in case the gfn falls in a hole one of the memslots bordering the hole is returned. Add this lookup mode as an option to search_memslots() so we don't have two almost identical functions for looking up a memslot by its gfn. Signed-off-by: Maciej S. Szmigiero [sean: tweaked helper names to keep gfn_to_memslot_approx() in s390] Reviewed-by: Sean Christopherson Message-Id: <171cd89b52c718dbe180ecd909b4437a64a7e2ec.1638817640.git.maciej.szmigiero@oracle.com> --- arch/s390/kvm/kvm-s390.c | 45 ++++++++------------------------------------- include/linux/kvm_host.h | 35 +++++++++++++++++++++++++++-------- virt/kvm/kvm_main.c | 2 +- 3 files changed, 36 insertions(+), 46 deletions(-) diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c index 251059f..631be75 100644 --- a/arch/s390/kvm/kvm-s390.c +++ b/arch/s390/kvm/kvm-s390.c @@ -1943,41 +1943,6 @@ out: /* for consistency */ #define KVM_S390_CMMA_SIZE_MAX ((u32)KVM_S390_SKEYS_MAX) -/* - * Similar to gfn_to_memslot, but returns the index of a memslot also when the - * address falls in a hole. In that case the index of one of the memslots - * bordering the hole is returned. - */ -static int gfn_to_memslot_approx(struct kvm_memslots *slots, gfn_t gfn) -{ - int start = 0, end = slots->used_slots; - int slot = atomic_read(&slots->last_used_slot); - struct kvm_memory_slot *memslots = slots->memslots; - - if (gfn >= memslots[slot].base_gfn && - gfn < memslots[slot].base_gfn + memslots[slot].npages) - return slot; - - while (start < end) { - slot = start + (end - start) / 2; - - if (gfn >= memslots[slot].base_gfn) - end = slot; - else - start = slot + 1; - } - - if (start >= slots->used_slots) - return slots->used_slots - 1; - - if (gfn >= memslots[start].base_gfn && - gfn < memslots[start].base_gfn + memslots[start].npages) { - atomic_set(&slots->last_used_slot, start); - } - - return start; -} - static int kvm_s390_peek_cmma(struct kvm *kvm, struct kvm_s390_cmma_log *args, u8 *res, unsigned long bufsize) { @@ -2001,11 +1966,17 @@ static int kvm_s390_peek_cmma(struct kvm *kvm, struct kvm_s390_cmma_log *args, return 0; } +static struct kvm_memory_slot *gfn_to_memslot_approx(struct kvm_memslots *slots, + gfn_t gfn) +{ + return ____gfn_to_memslot(slots, gfn, true); +} + static unsigned long kvm_s390_next_dirty_cmma(struct kvm_memslots *slots, unsigned long cur_gfn) { - int slotidx = gfn_to_memslot_approx(slots, cur_gfn); - struct kvm_memory_slot *ms = slots->memslots + slotidx; + struct kvm_memory_slot *ms = gfn_to_memslot_approx(slots, cur_gfn); + int slotidx = ms - slots->memslots; unsigned long ofs = cur_gfn - ms->base_gfn; if (ms->base_gfn + ms->npages <= cur_gfn) { diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index da0d4f2..2f80ce8 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1233,10 +1233,14 @@ try_get_memslot(struct kvm_memslots *slots, int slot_index, gfn_t gfn) * Returns a pointer to the memslot that contains gfn and records the index of * the slot in index. Otherwise returns NULL. * + * With "approx" set returns the memslot also when the address falls + * in a hole. In that case one of the memslots bordering the hole is + * returned. + * * 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, int *index) +search_memslots(struct kvm_memslots *slots, gfn_t gfn, int *index, bool approx) { int start = 0, end = slots->used_slots; struct kvm_memory_slot *memslots = slots->memslots; @@ -1254,22 +1258,26 @@ search_memslots(struct kvm_memslots *slots, gfn_t gfn, int *index) start = slot + 1; } + if (approx && start >= slots->used_slots) { + *index = slots->used_slots - 1; + return &memslots[slots->used_slots - 1]; + } + slot = try_get_memslot(slots, start, gfn); if (slot) { *index = start; return slot; } + if (approx) { + *index = start; + return &memslots[start]; + } 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) +____gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn, bool approx) { struct kvm_memory_slot *slot; int slot_index = atomic_read(&slots->last_used_slot); @@ -1278,7 +1286,7 @@ __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn) if (slot) return slot; - slot = search_memslots(slots, gfn, &slot_index); + slot = search_memslots(slots, gfn, &slot_index, approx); if (slot) { atomic_set(&slots->last_used_slot, slot_index); return slot; @@ -1287,6 +1295,17 @@ __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn) return NULL; } +/* + * __gfn_to_memslot() and its descendants are here to allow arch code to inline + * the lookups in hot paths. 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 ____gfn_to_memslot(slots, gfn, false); +} + static inline unsigned long __gfn_to_hva_memslot(const struct kvm_memory_slot *slot, gfn_t gfn) { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 8ccb1ac..6ca076a 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2141,7 +2141,7 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn * search_memslots() instead of __gfn_to_memslot() to avoid * thrashing the VM-wide last_used_index in kvm_memslots. */ - slot = search_memslots(slots, gfn, &slot_index); + slot = search_memslots(slots, gfn, &slot_index, false); if (slot) { vcpu->last_used_slot = slot_index; return slot; -- 2.7.4