From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
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>,
Anup Patel <anup.patel@wdc.com>,
Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Ben Gardon <bgardon@google.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v7 22/29] KVM: Use interval tree to do fast hva lookup in memslots
Date: Mon, 6 Dec 2021 20:54:28 +0100 [thread overview]
Message-ID: <d66b9974becaa9839be9c4e1a5de97b177b4ac20.1638817640.git.maciej.szmigiero@oracle.com> (raw)
In-Reply-To: <cover.1638817637.git.maciej.szmigiero@oracle.com>
From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>
The current memslots implementation only allows quick binary search by gfn,
quick lookup by hva is not possible - the implementation has to do a linear
scan of the whole memslots array, even though the operation being performed
might apply just to a single memslot.
This significantly hurts performance of per-hva operations with higher
memslot counts.
Since hva ranges can overlap between memslots an interval tree is needed
for tracking them.
[sean: handle interval tree updates in kvm_replace_memslot()]
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
arch/arm64/kvm/Kconfig | 1 +
arch/mips/kvm/Kconfig | 1 +
arch/powerpc/kvm/Kconfig | 1 +
arch/s390/kvm/Kconfig | 1 +
arch/x86/kvm/Kconfig | 1 +
include/linux/kvm_host.h | 3 +++
virt/kvm/kvm_main.c | 53 +++++++++++++++++++++++++++++-----------
7 files changed, 47 insertions(+), 14 deletions(-)
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 8ffcbe29395e..f1f8fc069a97 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -39,6 +39,7 @@ menuconfig KVM
select HAVE_KVM_IRQ_BYPASS
select HAVE_KVM_VCPU_RUN_PID_CHANGE
select SCHED_INFO
+ select INTERVAL_TREE
help
Support hosting virtualized guest machines.
diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
index a77297480f56..91d197bee9c0 100644
--- a/arch/mips/kvm/Kconfig
+++ b/arch/mips/kvm/Kconfig
@@ -27,6 +27,7 @@ config KVM
select KVM_MMIO
select MMU_NOTIFIER
select SRCU
+ select INTERVAL_TREE
help
Support for hosting Guest kernels.
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index ff581d70f20c..e4c24f524ba8 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -26,6 +26,7 @@ config KVM
select KVM_VFIO
select IRQ_BYPASS_MANAGER
select HAVE_KVM_IRQ_BYPASS
+ select INTERVAL_TREE
config KVM_BOOK3S_HANDLER
bool
diff --git a/arch/s390/kvm/Kconfig b/arch/s390/kvm/Kconfig
index 67a8e770e369..2e84d3922f7c 100644
--- a/arch/s390/kvm/Kconfig
+++ b/arch/s390/kvm/Kconfig
@@ -33,6 +33,7 @@ config KVM
select HAVE_KVM_NO_POLL
select SRCU
select KVM_VFIO
+ select INTERVAL_TREE
help
Support hosting paravirtualized guest machines using the SIE
virtualization capability on the mainframe. This should work
diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
index 619186138176..7618bef0a4a9 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -43,6 +43,7 @@ config KVM
select KVM_GENERIC_DIRTYLOG_READ_PROTECT
select KVM_VFIO
select SRCU
+ select INTERVAL_TREE
select HAVE_KVM_PM_NOTIFIER if PM
help
Support hosting fully virtualized guest machines using hardware
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index f3be79fb7d74..9f87adda1764 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -30,6 +30,7 @@
#include <linux/nospec.h>
#include <linux/notifier.h>
#include <linux/hashtable.h>
+#include <linux/interval_tree.h>
#include <linux/xarray.h>
#include <asm/signal.h>
@@ -430,6 +431,7 @@ static inline int kvm_vcpu_exiting_guest_mode(struct kvm_vcpu *vcpu)
struct kvm_memory_slot {
struct hlist_node id_node;
+ struct interval_tree_node hva_node;
gfn_t base_gfn;
unsigned long npages;
unsigned long *dirty_bitmap;
@@ -531,6 +533,7 @@ static inline int kvm_arch_vcpu_memslots_id(struct kvm_vcpu *vcpu)
*/
struct kvm_memslots {
u64 generation;
+ struct rb_root_cached hva_tree;
/*
* The mapping table from slot id to the index in memslots[].
*
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index f2eca32fbca8..502dbdf8ff96 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -514,6 +514,12 @@ static void kvm_null_fn(void)
}
#define IS_KVM_NULL_FN(fn) ((fn) == (void *)kvm_null_fn)
+/* Iterate over each memslot intersecting [start, last] (inclusive) range */
+#define kvm_for_each_memslot_in_hva_range(node, slots, start, last) \
+ for (node = interval_tree_iter_first(&slots->hva_tree, start, last); \
+ node; \
+ node = interval_tree_iter_next(node, start, last)) \
+
static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
const struct kvm_hva_range *range)
{
@@ -523,6 +529,9 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
struct kvm_memslots *slots;
int i, idx;
+ if (WARN_ON_ONCE(range->end <= range->start))
+ return 0;
+
/* A null handler is allowed if and only if on_lock() is provided. */
if (WARN_ON_ONCE(IS_KVM_NULL_FN(range->on_lock) &&
IS_KVM_NULL_FN(range->handler)))
@@ -531,15 +540,17 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
idx = srcu_read_lock(&kvm->srcu);
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+ struct interval_tree_node *node;
+
slots = __kvm_memslots(kvm, i);
- kvm_for_each_memslot(slot, slots) {
+ kvm_for_each_memslot_in_hva_range(node, slots,
+ range->start, range->end - 1) {
unsigned long hva_start, hva_end;
+ slot = container_of(node, struct kvm_memory_slot, hva_node);
hva_start = max(range->start, slot->userspace_addr);
hva_end = min(range->end, slot->userspace_addr +
(slot->npages << PAGE_SHIFT));
- if (hva_start >= hva_end)
- continue;
/*
* To optimize for the likely case where the address
@@ -875,6 +886,7 @@ static struct kvm_memslots *kvm_alloc_memslots(void)
if (!slots)
return NULL;
+ slots->hva_tree = RB_ROOT_CACHED;
hash_init(slots->id_hash);
return slots;
@@ -1279,21 +1291,28 @@ static void kvm_replace_memslot(struct kvm_memslots *slots,
struct kvm_memory_slot *new)
{
/*
- * Remove the old memslot from the hash list, copying the node data
- * would corrupt the list.
+ * Remove the old memslot from the hash list and interval tree, copying
+ * the node data would corrupt the structures.
*/
if (old) {
hash_del(&old->id_node);
+ interval_tree_remove(&old->hva_node, &slots->hva_tree);
if (!new)
return;
/* Copy the source *data*, not the pointer, to the destination. */
*new = *old;
+ } else {
+ /* If @old is NULL, initialize @new's hva range. */
+ new->hva_node.start = new->userspace_addr;
+ new->hva_node.last = new->userspace_addr +
+ (new->npages << PAGE_SHIFT) - 1;
}
/* (Re)Add the new memslot. */
hash_add(slots->id_hash, &new->id_node, new->id);
+ interval_tree_insert(&new->hva_node, &slots->hva_tree);
}
static void kvm_shift_memslot(struct kvm_memslots *slots, int dst, int src)
@@ -1324,7 +1343,7 @@ static inline void kvm_memslot_delete(struct kvm_memslots *slots,
atomic_set(&slots->last_used_slot, 0);
/*
- * Remove the to-be-deleted memslot from the list _before_ shifting
+ * Remove the to-be-deleted memslot from the list/tree _before_ shifting
* the trailing memslots forward, its data will be overwritten.
* Defer the (somewhat pointless) copying of the memslot until after
* the last slot has been shifted to avoid overwriting said last slot.
@@ -1351,7 +1370,8 @@ static inline int kvm_memslot_insert_back(struct kvm_memslots *slots)
* itself is not preserved in the array, i.e. not swapped at this time, only
* its new index into the array is tracked. Returns the changed memslot's
* current index into the memslots array.
- * The memslot at the returned index will not be in @slots->id_hash by then.
+ * The memslot at the returned index will not be in @slots->hva_tree or
+ * @slots->id_hash by then.
* @memslot is a detached struct with desired final data of the changed slot.
*/
static inline int kvm_memslot_move_backward(struct kvm_memslots *slots,
@@ -1365,10 +1385,10 @@ static inline int kvm_memslot_move_backward(struct kvm_memslots *slots,
return -1;
/*
- * Delete the slot from the hash table before sorting the remaining
- * slots, the slot's data may be overwritten when copying slots as part
- * of the sorting proccess. update_memslots() will unconditionally
- * rewrite the entire slot and re-add it to the hash table.
+ * Delete the slot from the hash table and interval tree before sorting
+ * the remaining slots, the slot's data may be overwritten when copying
+ * slots as part of the sorting proccess. update_memslots() will
+ * unconditionally rewrite and re-add the entire slot.
*/
kvm_replace_memslot(slots, oldslot, NULL);
@@ -1394,10 +1414,12 @@ static inline int kvm_memslot_move_backward(struct kvm_memslots *slots,
* is not preserved in the array, i.e. not swapped at this time, only its new
* index into the array is tracked. Returns the changed memslot's final index
* into the memslots array.
- * The memslot at the returned index will not be in @slots->id_hash by then.
+ * The memslot at the returned index will not be in @slots->hva_tree or
+ * @slots->id_hash by then.
* @memslot is a detached struct with desired final data of the new or
* changed slot.
- * Assumes that the memslot at @start index is not in @slots->id_hash.
+ * Assumes that the memslot at @start index is not in @slots->hva_tree or
+ * @slots->id_hash.
*/
static inline int kvm_memslot_move_forward(struct kvm_memslots *slots,
struct kvm_memory_slot *memslot,
@@ -1590,9 +1612,12 @@ static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old,
memcpy(slots, old, kvm_memslots_size(old->used_slots));
+ slots->hva_tree = RB_ROOT_CACHED;
hash_init(slots->id_hash);
- kvm_for_each_memslot(memslot, slots)
+ kvm_for_each_memslot(memslot, slots) {
+ interval_tree_insert(&memslot->hva_node, &slots->hva_tree);
hash_add(slots->id_hash, &memslot->id_node, memslot->id);
+ }
return slots;
}
next prev parent reply other threads:[~2021-12-06 19:57 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-06 19:54 [PATCH v7 00/29] KVM: Scalable memslots implementation Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 01/29] KVM: Require total number of memslot pages to fit in an unsigned long Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 02/29] KVM: Open code kvm_delete_memslot() into its only caller Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 03/29] KVM: Resync only arch fields when slots_arch_lock gets reacquired Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 04/29] KVM: Use "new" memslot's address space ID instead of dedicated param Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 05/29] KVM: Let/force architectures to deal with arch specific memslot data Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 06/29] KVM: arm64: Use "new" memslot instead of userspace memory region Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 07/29] KVM: MIPS: Drop pr_debug from memslot commit to avoid using "mem" Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 08/29] KVM: PPC: Avoid referencing userspace memory region in memslot updates Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 09/29] KVM: s390: Use "new" memslot instead of userspace memory region Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 10/29] KVM: x86: " Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 11/29] KVM: RISC-V: " Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 12/29] KVM: Stop passing kvm_userspace_memory_region to arch memslot hooks Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 13/29] KVM: Use prepare/commit hooks to handle generic memslot metadata updates Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 14/29] KVM: x86: Don't assume old/new memslots are non-NULL at memslot commit Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 15/29] KVM: s390: Skip gfn/size sanity checks on memslot DELETE or FLAGS_ONLY Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 16/29] KVM: Don't make a full copy of the old memslot in __kvm_set_memory_region() Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 17/29] KVM: x86: Don't call kvm_mmu_change_mmu_pages() if the count hasn't changed Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 18/29] KVM: x86: Use nr_memslot_pages to avoid traversing the memslots array Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 19/29] KVM: Integrate gfn_to_memslot_approx() into search_memslots() Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 20/29] KVM: Move WARN on invalid memslot index to update_memslots() Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 21/29] KVM: Resolve memslot ID via a hash table instead of via a static array Maciej S. Szmigiero
2021-12-06 19:54 ` Maciej S. Szmigiero [this message]
2021-12-06 19:54 ` [PATCH v7 23/29] KVM: s390: Introduce kvm_s390_get_gfn_end() Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 24/29] KVM: Keep memslots in tree-based structures instead of array-based ones Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 25/29] KVM: Call kvm_arch_flush_shadow_memslot() on the old slot in kvm_invalidate_memslot() Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 26/29] KVM: Optimize gfn lookup in kvm_zap_gfn_range() Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 27/29] KVM: Optimize overlapping memslots check Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 28/29] KVM: Wait 'til the bitter end to initialize the "new" memslot Maciej S. Szmigiero
2021-12-06 19:54 ` [PATCH v7 29/29] KVM: Dynamically allocate "new" memslots from the get-go Maciej S. Szmigiero
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