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KVM: Integrate gfn_to_memslot_approx() into search_memslots()

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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 <maciej.szmigiero@oracle.com>
[sean: tweaked helper names to keep gfn_to_memslot_approx() in s390]
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <171cd89b52c718dbe180ecd909b4437a64a7e2ec.1638817640.git.maciej.szmigiero@oracle.com>
This commit is contained in:
Maciej S. Szmigiero 2021-12-06 20:54:25 +01:00 committed by Paolo Bonzini
parent f5756029ee
commit c928bfc263
3 changed files with 36 additions and 46 deletions
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45
arch/s390/kvm/kvm-s390.c
View File

@ -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) {

35
include/linux/kvm_host.h
View File

@ -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)
{

2
virt/kvm/kvm_main.c
View File

@ -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;