From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx>
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.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
---
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 | 8 ++++++++
virt/kvm/kvm_main.c | 43 +++++++++++++++++++++++++++++++++-------
7 files changed, 49 insertions(+), 7 deletions(-)
diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index 3964acf5451e..f075e9939a2a 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -40,6 +40,7 @@ menuconfig KVM
select HAVE_KVM_VCPU_RUN_PID_CHANGE
select TASKSTATS
select TASK_DELAY_ACCT
+ 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 e45644657d49..519d6d3642a5 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 f6b93a35ce14..ee15f7e113c8 100644
--- a/arch/x86/kvm/Kconfig
+++ b/arch/x86/kvm/Kconfig
@@ -46,6 +46,7 @@ config KVM
select KVM_GENERIC_DIRTYLOG_READ_PROTECT
select KVM_VFIO
select SRCU
+ select INTERVAL_TREE
help
Support hosting fully virtualized guest machines using hardware
virtualization extensions. You will need a fairly recent
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d3a35646dfd8..f59847b6e9b3 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -27,6 +27,7 @@
#include <linux/rcuwait.h>
#include <linux/refcount.h>
#include <linux/nospec.h>
+#include <linux/interval_tree.h>
#include <linux/hashtable.h>
#include <asm/signal.h>
@@ -358,6 +359,7 @@ 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;
@@ -459,6 +461,7 @@ 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[]. */
DECLARE_HASHTABLE(id_hash, 7);
atomic_t lru_slot;
@@ -679,6 +682,11 @@ static inline struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu)
return __kvm_memslots(vcpu->kvm, as_id);
}
+#define kvm_for_each_hva_range_memslot(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 inline
struct kvm_memory_slot *id_to_memslot(struct kvm_memslots *slots, int id)
{
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 50f9bc9bb1e0..a55309432c9a 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -488,6 +488,9 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
struct kvm_memslots *slots;
int i, idx;
+ if (range->end == range->start || WARN_ON(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)))
@@ -507,15 +510,18 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
}
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_hva_range_memslot(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
@@ -787,6 +793,7 @@ 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;
@@ -1113,10 +1120,14 @@ static inline void kvm_memslot_delete(struct kvm_memslots *slots,
atomic_set(&slots->lru_slot, 0);
for (i = dmemslot - mslots; i < slots->used_slots; i++) {
+ interval_tree_remove(&mslots[i].hva_node, &slots->hva_tree);
hash_del(&mslots[i].id_node);
+
mslots[i] = mslots[i + 1];
+ interval_tree_insert(&mslots[i].hva_node, &slots->hva_tree);
hash_add(slots->id_hash, &mslots[i].id_node, mslots[i].id);
}
+ interval_tree_remove(&mslots[i].hva_node, &slots->hva_tree);
hash_del(&mslots[i].id_node);
mslots[i] = *memslot;
}
@@ -1136,7 +1147,8 @@ 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,
@@ -1154,6 +1166,7 @@ static inline int kvm_memslot_move_backward(struct kvm_memslots *slots,
* update_memslots() will unconditionally overwrite and re-add the
* target memslot so it has to be removed here first
*/
+ interval_tree_remove(&mmemslot->hva_node, &slots->hva_tree);
hash_del(&mmemslot->id_node);
/*
@@ -1168,8 +1181,11 @@ static inline int kvm_memslot_move_backward(struct kvm_memslots *slots,
WARN_ON_ONCE(memslot->base_gfn == mslots[i + 1].base_gfn);
/* Shift the next memslot forward one and update its index. */
+ interval_tree_remove(&mslots[i + 1].hva_node, &slots->hva_tree);
hash_del(&mslots[i + 1].id_node);
+
mslots[i] = mslots[i + 1];
+ interval_tree_insert(&mslots[i].hva_node, &slots->hva_tree);
hash_add(slots->id_hash, &mslots[i].id_node, mslots[i].id);
}
return i;
@@ -1181,10 +1197,12 @@ 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,
@@ -1200,8 +1218,11 @@ static inline int kvm_memslot_move_forward(struct kvm_memslots *slots,
WARN_ON_ONCE(memslot->base_gfn == mslots[i - 1].base_gfn);
/* Shift the next memslot back one and update its index. */
+ interval_tree_remove(&mslots[i - 1].hva_node, &slots->hva_tree);
hash_del(&mslots[i - 1].id_node);
+
mslots[i] = mslots[i - 1];
+ interval_tree_insert(&mslots[i].hva_node, &slots->hva_tree);
hash_add(slots->id_hash, &mslots[i].id_node, mslots[i].id);
}
return i;
@@ -1274,6 +1295,11 @@ static void update_memslots(struct kvm_memslots *slots,
* its index accordingly.
*/
slots->memslots[i] = *memslot;
+ slots->memslots[i].hva_node.start = memslot->userspace_addr;
+ slots->memslots[i].hva_node.last = memslot->userspace_addr +
+ (memslot->npages << PAGE_SHIFT) - 1;
+ interval_tree_insert(&slots->memslots[i].hva_node,
+ &slots->hva_tree);
hash_add(slots->id_hash, &slots->memslots[i].id_node,
memslot->id);
}
@@ -1355,9 +1381,12 @@ static struct kvm_memslots *kvm_dup_memslots(struct kvm_memslots *old,
memcpy(slots, old, old_size);
+ 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;
}
