From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Paolo Bonzini <pbonzini@redhat.com>,
Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>,
Igor Mammedov <imammedo@redhat.com>,
Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Huacai Chen <chenhuacai@kernel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
Paul Mackerras <paulus@ozlabs.org>,
Christian Borntraeger <borntraeger@de.ibm.com>,
Janosch Frank <frankja@linux.ibm.com>,
David Hildenbrand <david@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 05/13] KVM: Integrate gfn_to_memslot_approx() into search_memslots()
Date: Fri, 13 Aug 2021 21:33:18 +0200 [thread overview]
Message-ID: <278846ca7b51ab945bdaf1418f8ca94572f228d6.1628871413.git.maciej.szmigiero@oracle.com> (raw)
In-Reply-To: <cover.1628871411.git.maciej.szmigiero@oracle.com>
From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.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@oracle.com>
---
arch/s390/kvm/kvm-s390.c | 39 ++-------------------------------------
include/linux/kvm_host.h | 25 ++++++++++++++++++++++---
virt/kvm/kvm_main.c | 2 +-
3 files changed, 25 insertions(+), 41 deletions(-)
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 4bed65dbad5e..6b3f05086fae 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1941,41 +1941,6 @@ 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)
{
@@ -2002,8 +1967,8 @@ static int kvm_s390_peek_cmma(struct kvm *kvm, struct kvm_s390_cmma_log *args,
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, true);
+ 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 2d62581b400e..6d0bbd6c8554 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1232,10 +1232,14 @@ 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;
@@ -1253,11 +1257,20 @@ 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;
}
@@ -1268,7 +1281,7 @@ search_memslots(struct kvm_memslots *slots, gfn_t gfn, int *index)
* 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_approx(struct kvm_memslots *slots, gfn_t gfn, bool approx)
{
struct kvm_memory_slot *slot;
int slot_index = atomic_read(&slots->last_used_slot);
@@ -1277,7 +1290,7 @@ __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;
@@ -1286,6 +1299,12 @@ __gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
return NULL;
}
+static inline struct kvm_memory_slot *
+__gfn_to_memslot(struct kvm_memslots *slots, gfn_t gfn)
+{
+ return __gfn_to_memslot_approx(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 207306f7c559..03ef42d2e421 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2074,7 +2074,7 @@ 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;
next prev parent reply other threads:[~2021-08-13 20:01 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-13 19:33 [PATCH v4 00/13] KVM: Scalable memslots implementation Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 01/13] KVM: x86: Cache total page count to avoid traversing the memslot array Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 02/13] KVM: x86: Don't call kvm_mmu_change_mmu_pages() if the count hasn't changed Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 03/13] KVM: Add "old" memslot parameter to kvm_arch_prepare_memory_region() Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 04/13] KVM: x86: Move n_memslots_pages recalc " Maciej S. Szmigiero
2021-08-13 19:33 ` Maciej S. Szmigiero [this message]
2021-08-18 14:29 ` [PATCH v4 05/13] KVM: Integrate gfn_to_memslot_approx() into search_memslots() Claudio Imbrenda
2021-08-13 19:33 ` [PATCH v4 06/13] KVM: Move WARN on invalid memslot index to update_memslots() Maciej S. Szmigiero
2021-08-18 14:29 ` Claudio Imbrenda
2021-08-18 14:35 ` David Hildenbrand
2021-08-18 21:43 ` Maciej S. Szmigiero
2021-08-20 9:27 ` David Hildenbrand
2021-08-13 19:33 ` [PATCH v4 07/13] KVM: Just resync arch fields when slots_arch_lock gets reacquired Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 08/13] KVM: Resolve memslot ID via a hash table instead of via a static array Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 09/13] KVM: Use interval tree to do fast hva lookup in memslots Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 10/13] KVM: s390: Introduce kvm_s390_get_gfn_end() Maciej S. Szmigiero
2021-08-18 14:31 ` Claudio Imbrenda
2021-08-13 19:33 ` [PATCH v4 11/13] KVM: Keep memslots in tree-based structures instead of array-based ones Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 12/13] KVM: Optimize gfn lookup in kvm_zap_gfn_range() Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 13/13] KVM: Optimize overlapping memslots check Maciej S. Szmigiero
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