[PATCH v2 4/8] KVM: Introduce memslots hva tree
From: Maciej S. Szmigiero
Date: Tue Apr 13 2021 - 10:11:25 EST
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/arm64/kvm/mmu.c | 10 +++++++---
arch/mips/kvm/Kconfig | 1 +
arch/mips/kvm/mmu.c | 10 +++++++---
arch/powerpc/kvm/Kconfig | 1 +
arch/powerpc/kvm/book3s_64_mmu_hv.c | 10 +++++++---
arch/powerpc/kvm/book3s_pr.c | 10 +++++++---
arch/s390/kvm/Kconfig | 1 +
arch/x86/kvm/Kconfig | 1 +
arch/x86/kvm/mmu/mmu.c | 11 +++++++---
arch/x86/kvm/mmu/tdp_mmu.c | 13 +++++++++---
include/linux/kvm_host.h | 8 ++++++++
virt/kvm/kvm_main.c | 31 +++++++++++++++++++++++++----
13 files changed, 86 insertions(+), 22 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/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 4b7e1e327337..4b0ac98a5a53 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -1073,21 +1073,25 @@ static int handle_hva_to_gpa(struct kvm *kvm,
void *data)
{
struct kvm_memslots *slots;
+ struct interval_tree_node *node;
struct kvm_memory_slot *memslot;
int ret = 0;
+ if (end == start || WARN_ON(end < start))
+ return 0;
+
slots = kvm_memslots(kvm);
/* we only care about the pages that the guest sees */
- kvm_for_each_memslot(memslot, slots) {
+ kvm_for_each_hva_range_memslot(node, slots, start, end - 1) {
unsigned long hva_start, hva_end;
gfn_t gpa;
+ memslot = container_of(node, struct kvm_memory_slot,
+ hva_node);
hva_start = max(start, memslot->userspace_addr);
hva_end = min(end, memslot->userspace_addr +
(memslot->npages << PAGE_SHIFT));
- if (hva_start >= hva_end)
- continue;
gpa = hva_to_gfn_memslot(hva_start, memslot) << PAGE_SHIFT;
ret |= handler(kvm, gpa, (u64)(hva_end - hva_start), data);
diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
index 032b3fca6cbb..5ba260f38e75 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/mips/kvm/mmu.c b/arch/mips/kvm/mmu.c
index 3dabeda82458..0c7c48f08ec2 100644
--- a/arch/mips/kvm/mmu.c
+++ b/arch/mips/kvm/mmu.c
@@ -449,21 +449,25 @@ static int handle_hva_to_gpa(struct kvm *kvm,
void *data)
{
struct kvm_memslots *slots;
+ struct interval_tree_node *node;
struct kvm_memory_slot *memslot;
int ret = 0;
+ if (end == start || WARN_ON(end < start))
+ return 0;
+
slots = kvm_memslots(kvm);
/* we only care about the pages that the guest sees */
- kvm_for_each_memslot(memslot, slots) {
+ kvm_for_each_hva_range_memslot(node, slots, start, end - 1) {
unsigned long hva_start, hva_end;
gfn_t gfn, gfn_end;
+ memslot = container_of(node, struct kvm_memory_slot,
+ hva_node);
hva_start = max(start, memslot->userspace_addr);
hva_end = min(end, memslot->userspace_addr +
(memslot->npages << PAGE_SHIFT));
- if (hva_start >= hva_end)
- continue;
/*
* {gfn(page) | page intersects with [hva_start, hva_end)} =
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/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c
index bb6773594cf8..fca2a978617c 100644
--- a/arch/powerpc/kvm/book3s_64_mmu_hv.c
+++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c
@@ -763,18 +763,22 @@ static int kvm_handle_hva_range(struct kvm *kvm,
int ret;
int retval = 0;
struct kvm_memslots *slots;
+ struct interval_tree_node *node;
struct kvm_memory_slot *memslot;
+ if (end == start || WARN_ON(end < start))
+ return 0;
+
slots = kvm_memslots(kvm);
- kvm_for_each_memslot(memslot, slots) {
+ kvm_for_each_hva_range_memslot(node, slots, start, end - 1) {
unsigned long hva_start, hva_end;
gfn_t gfn, gfn_end;
+ memslot = container_of(node, struct kvm_memory_slot,
+ hva_node);
hva_start = max(start, memslot->userspace_addr);
hva_end = min(end, memslot->userspace_addr +
(memslot->npages << PAGE_SHIFT));
- if (hva_start >= hva_end)
- continue;
/*
* {gfn(page) | page intersects with [hva_start, hva_end)} =
* {gfn, gfn+1, ..., gfn_end-1}.
diff --git a/arch/powerpc/kvm/book3s_pr.c b/arch/powerpc/kvm/book3s_pr.c
index 913944dc3620..d0a7127403f0 100644
--- a/arch/powerpc/kvm/book3s_pr.c
+++ b/arch/powerpc/kvm/book3s_pr.c
@@ -431,18 +431,22 @@ static void do_kvm_unmap_hva(struct kvm *kvm, unsigned long start,
long i;
struct kvm_vcpu *vcpu;
struct kvm_memslots *slots;
+ struct interval_tree_node *node;
struct kvm_memory_slot *memslot;
+ if (end == start || WARN_ON(end < start))
+ return;
+
slots = kvm_memslots(kvm);
- kvm_for_each_memslot(memslot, slots) {
+ kvm_for_each_hva_range_memslot(node, slots, start, end - 1) {
unsigned long hva_start, hva_end;
gfn_t gfn, gfn_end;
+ memslot = container_of(node, struct kvm_memory_slot,
+ hva_node);
hva_start = max(start, memslot->userspace_addr);
hva_end = min(end, memslot->userspace_addr +
(memslot->npages << PAGE_SHIFT));
- if (hva_start >= hva_end)
- continue;
/*
* {gfn(page) | page intersects with [hva_start, hva_end)} =
* {gfn, gfn+1, ..., gfn_end-1}.
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 a788d5120d4d..59225775e4f5 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/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 762314b04a39..75fa497aa27f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1430,17 +1430,22 @@ static __always_inline int kvm_handle_hva_range(struct kvm *kvm,
int ret = 0;
int i;
+ if (end == start || WARN_ON(end < start))
+ return 0;
+
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+ struct interval_tree_node *node;
+
slots = __kvm_memslots(kvm, i);
- kvm_for_each_memslot(memslot, slots) {
+ kvm_for_each_hva_range_memslot(node, slots, start, end - 1) {
unsigned long hva_start, hva_end;
gfn_t gfn_start, gfn_end;
+ memslot = container_of(node, struct kvm_memory_slot,
+ hva_node);
hva_start = max(start, memslot->userspace_addr);
hva_end = min(end, memslot->userspace_addr +
(memslot->npages << PAGE_SHIFT));
- if (hva_start >= hva_end)
- continue;
/*
* {gfn(page) | page intersects with [hva_start, hva_end)} =
* {gfn_start, gfn_start+1, ..., gfn_end-1}.
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index ccf0d774a181..69683028763c 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -889,18 +889,25 @@ static __always_inline int kvm_tdp_mmu_handle_hva_range(struct kvm *kvm,
int ret = 0;
int as_id;
+ if (end == start || WARN_ON(end < start))
+ return 0;
+
for (as_id = 0; as_id < KVM_ADDRESS_SPACE_NUM; as_id++) {
for_each_tdp_mmu_root_yield_safe(kvm, root, as_id) {
+ struct interval_tree_node *node;
+
slots = __kvm_memslots(kvm, as_id);
- kvm_for_each_memslot(memslot, slots) {
+ kvm_for_each_hva_range_memslot(node, slots,
+ start, end - 1) {
unsigned long hva_start, hva_end;
gfn_t gfn_start, gfn_end;
+ memslot = container_of(node,
+ struct kvm_memory_slot,
+ hva_node);
hva_start = max(start, memslot->userspace_addr);
hva_end = min(end, memslot->userspace_addr +
(memslot->npages << PAGE_SHIFT));
- if (hva_start >= hva_end)
- continue;
/*
* {gfn(page) | page intersects with [hva_start, hva_end)} =
* {gfn_start, gfn_start+1, ..., gfn_end-1}.
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e4aadb9875e9..b8196cbd2c6f 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>
@@ -352,6 +353,7 @@ 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;
@@ -453,6 +455,7 @@ 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;
@@ -673,6 +676,11 @@ 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 8f0b49d937d1..37b44cde9ae7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -662,6 +662,7 @@ 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;
@@ -988,10 +989,14 @@ 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;
}
@@ -1011,7 +1016,8 @@ 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,
@@ -1029,6 +1035,7 @@ 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);
/*
@@ -1043,8 +1050,11 @@ 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;
@@ -1056,10 +1066,12 @@ 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,
@@ -1075,8 +1087,11 @@ 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;
@@ -1149,6 +1164,11 @@ 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);
}
@@ -1230,9 +1250,12 @@ 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;
}