Commit 0f22af94 authored by David Matlack's avatar David Matlack Committed by Paolo Bonzini
Browse files

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: default avatarDavid Matlack <dmatlack@google.com>
Message-Id: <20210804222844.1419481-3-dmatlack@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 87689270

arch/powerpc/kvm/book3s_64_vio.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

arch/powerpc/kvm/book3s_64_vio_hv.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

include/linux/kvm_host.h

+48 −16
Original line number Diff line number Diff line
@@ -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