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Message-Id: <0182ed54994ca94d2204f386e0cebc414f4ec8fc.1638304316.git.maciej.szmigiero@oracle.com>
Date: Tue, 30 Nov 2021 22:41:32 +0100
From: "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
To: Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Igor Mammedov <imammedo@...hat.com>,
Marc Zyngier <maz@...nel.org>,
James Morse <james.morse@....com>,
Julien Thierry <julien.thierry.kdev@...il.com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Huacai Chen <chenhuacai@...nel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
Paul Mackerras <paulus@...abs.org>,
Christian Borntraeger <borntraeger@...ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
David Hildenbrand <david@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Anup Patel <anup.patel@....com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Alexandru Elisei <alexandru.elisei@....com>,
Atish Patra <atish.patra@....com>,
Ben Gardon <bgardon@...gle.com>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v6 19/29] KVM: Integrate gfn_to_memslot_approx() into search_memslots()
From: "Maciej S. Szmigiero" <maciej.szmigiero@...cle.com>
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@...cle.com>
[sean: tweaked helper names to keep gfn_to_memslot_approx() in s390]
Signed-off-by: Sean Christopherson <seanjc@...gle.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 a92e36d8a827..b0fa2592b4ef 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1943,41 +1943,6 @@ static long kvm_s390_set_skeys(struct kvm *kvm, struct kvm_s390_skeys *args)
/* 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 9f984867c297..86562ffb6ea4 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1250,10 +1250,14 @@ 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;
@@ -1271,22 +1275,26 @@ 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);
@@ -1295,7 +1303,7 @@ __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;
@@ -1304,6 +1312,17 @@ __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 1f37c4ce5f97..aca39b587cdb 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2143,7 +2143,7 @@ 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;
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