[RFC PATCH 1/3] KVM: selftests: memstress: Add option to enable dirty-ring on VM creation
From: Leonardo Bras
Date: Wed Jun 24 2026 - 13:17:51 EST
Dirty-ring should be enabled after the VM is created, but before the
creation of any cpu. To to so, add an option on memstress_create_vm() that
takes dirty-ring size, and enables it at the correct moment.
This required a new function memstress_vm_create_with_vcpus() to be
created based on the previously used __vm_create_with_vcpus();
Signed-off-by: Leonardo Bras <leo.bras@xxxxxxx>
---
.../testing/selftests/kvm/include/memstress.h | 3 +-
.../selftests/kvm/access_tracking_perf_test.c | 2 +-
.../selftests/kvm/demand_paging_test.c | 2 +-
.../selftests/kvm/dirty_log_perf_test.c | 2 +-
tools/testing/selftests/kvm/lib/memstress.c | 34 ++++++++++++++++---
.../kvm/memslot_modification_stress_test.c | 2 +-
.../kvm/x86/dirty_log_page_splitting_test.c | 2 +-
7 files changed, 37 insertions(+), 10 deletions(-)
diff --git a/tools/testing/selftests/kvm/include/memstress.h b/tools/testing/selftests/kvm/include/memstress.h
index 0d1d6230cc05..e17f344978af 100644
--- a/tools/testing/selftests/kvm/include/memstress.h
+++ b/tools/testing/selftests/kvm/include/memstress.h
@@ -51,21 +51,22 @@ struct memstress_args {
bool stop_vcpus;
struct memstress_vcpu_args vcpu_args[KVM_MAX_VCPUS];
};
extern struct memstress_args memstress_args;
struct kvm_vm *memstress_create_vm(enum vm_guest_mode mode, int nr_vcpus,
u64 vcpu_memory_bytes, int slots,
enum vm_mem_backing_src_type backing_src,
- bool partition_vcpu_memory_access);
+ bool partition_vcpu_memory_access,
+ u32 dirty_ring_size);
void memstress_destroy_vm(struct kvm_vm *vm);
void memstress_set_write_percent(struct kvm_vm *vm, u32 write_percent);
void memstress_set_random_access(struct kvm_vm *vm, bool random_access);
void memstress_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct memstress_vcpu_args *));
void memstress_join_vcpu_threads(int vcpus);
void memstress_guest_code(u32 vcpu_id);
u64 memstress_nested_pages(int nr_vcpus);
diff --git a/tools/testing/selftests/kvm/access_tracking_perf_test.c b/tools/testing/selftests/kvm/access_tracking_perf_test.c
index 4415c94b2866..f78d56265d89 100644
--- a/tools/testing/selftests/kvm/access_tracking_perf_test.c
+++ b/tools/testing/selftests/kvm/access_tracking_perf_test.c
@@ -402,21 +402,21 @@ static void mark_memory_idle(struct kvm_vm *vm, int nr_vcpus)
run_iteration(vm, nr_vcpus, "Mark memory idle (page_idle)");
}
static void run_test(enum vm_guest_mode mode, void *arg)
{
struct test_params *params = arg;
struct kvm_vm *vm;
int nr_vcpus = params->nr_vcpus;
vm = memstress_create_vm(mode, nr_vcpus, params->vcpu_memory_bytes, 1,
- params->backing_src, !overlap_memory_access);
+ params->backing_src, !overlap_memory_access, 0);
/*
* If guest_page_size is larger than the host's page size, the
* guest (memstress) will only fault in a subset of the host's pages.
*/
test_pages = params->nr_vcpus * params->vcpu_memory_bytes /
max(memstress_args.guest_page_size,
(u64)getpagesize());
memstress_start_vcpu_threads(nr_vcpus, vcpu_thread_main);
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 302c4923d093..92246e27ef74 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -155,21 +155,21 @@ static void run_test(enum vm_guest_mode mode, void *arg)
struct test_params *p = arg;
struct uffd_desc **uffd_descs = NULL;
u64 uffd_region_size;
struct timespec start;
struct timespec ts_diff;
double vcpu_paging_rate;
struct kvm_vm *vm;
int i, num_uffds = 0;
vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,
- p->src_type, p->partition_vcpu_memory_access);
+ p->src_type, p->partition_vcpu_memory_access, 0);
demand_paging_size = get_backing_src_pagesz(p->src_type);
guest_data_prototype = malloc(demand_paging_size);
TEST_ASSERT(guest_data_prototype,
"Failed to allocate buffer for guest data pattern");
memset(guest_data_prototype, 0xAB, demand_paging_size);
if (p->uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {
num_uffds = p->single_uffd ? 1 : nr_vcpus;
diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index ef779fa91827..69b38791440e 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -112,21 +112,21 @@ static void run_test(enum vm_guest_mode mode, void *arg)
struct timespec start;
struct timespec ts_diff;
struct timespec get_dirty_log_total = (struct timespec){0};
struct timespec vcpu_dirty_total = (struct timespec){0};
struct timespec avg;
struct timespec clear_dirty_log_total = (struct timespec){0};
int i;
vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size,
p->slots, p->backing_src,
- p->partition_vcpu_memory_access);
+ p->partition_vcpu_memory_access, 0);
memstress_set_write_percent(vm, p->write_percent);
guest_num_pages = (nr_vcpus * guest_percpu_mem_size) >> vm->page_shift;
guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
host_num_pages = vm_num_host_pages(mode, guest_num_pages);
pages_per_slot = host_num_pages / p->slots;
bitmaps = memstress_alloc_bitmaps(p->slots, pages_per_slot);
diff --git a/tools/testing/selftests/kvm/lib/memstress.c b/tools/testing/selftests/kvm/lib/memstress.c
index 6dcd15910a06..c9f85533ffff 100644
--- a/tools/testing/selftests/kvm/lib/memstress.c
+++ b/tools/testing/selftests/kvm/lib/memstress.c
@@ -114,24 +114,49 @@ void memstress_setup_vcpus(struct kvm_vm *vm, int nr_vcpus,
}
vcpu_args_set(vcpus[i], 1, i);
pr_debug("Added VCPU %d with test mem gpa [%lx, %lx)\n",
i, vcpu_args->gpa, vcpu_args->gpa +
(vcpu_args->pages * args->guest_page_size));
}
}
+static struct kvm_vm *memstress_vm_create_with_vcpus(struct vm_shape shape,
+ u32 nr_vcpus,
+ u64 extra_mem_pages,
+ void *guest_code,
+ struct kvm_vcpu *vcpus[],
+ u32 dirty_ring_size)
+{
+ struct kvm_vm *vm;
+ int i;
+
+ TEST_ASSERT(!nr_vcpus || vcpus, "Must provide vCPU array");
+
+ vm = __vm_create(shape, nr_vcpus, extra_mem_pages);
+
+ if (dirty_ring_size)
+ vm_enable_dirty_ring(vm, dirty_ring_size);
+
+ for (i = 0; i < nr_vcpus; ++i)
+ vcpus[i] = vm_vcpu_add(vm, i, guest_code);
+
+ kvm_arch_vm_finalize_vcpus(vm);
+ return vm;
+}
+
struct kvm_vm *memstress_create_vm(enum vm_guest_mode mode, int nr_vcpus,
u64 vcpu_memory_bytes, int slots,
enum vm_mem_backing_src_type backing_src,
- bool partition_vcpu_memory_access)
+ bool partition_vcpu_memory_access,
+ u32 dirty_ring_size)
{
struct memstress_args *args = &memstress_args;
struct kvm_vm *vm;
u64 guest_num_pages, slot0_pages = 0;
u64 backing_src_pagesz = get_backing_src_pagesz(backing_src);
u64 region_end_gfn;
int i;
pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
@@ -160,23 +185,24 @@ struct kvm_vm *memstress_create_vm(enum vm_guest_mode mode, int nr_vcpus,
* in-memory data structures.
*/
if (args->nested)
slot0_pages += memstress_nested_pages(nr_vcpus);
/*
* Pass guest_num_pages to populate the page tables for test memory.
* The memory is also added to memslot 0, but that's a benign side
* effect as KVM allows aliasing HVAs in meslots.
*/
- vm = __vm_create_with_vcpus(VM_SHAPE(mode), nr_vcpus,
- slot0_pages + guest_num_pages,
- memstress_guest_code, vcpus);
+ vm = memstress_vm_create_with_vcpus(VM_SHAPE(mode), nr_vcpus,
+ slot0_pages + guest_num_pages,
+ memstress_guest_code, vcpus,
+ dirty_ring_size);
args->vm = vm;
/* Put the test region at the top guest physical memory. */
region_end_gfn = vm->max_gfn + 1;
#ifdef __x86_64__
/*
* When running vCPUs in L2, restrict the test region to 48 bits to
* avoid needing 5-level page tables to identity map L2.
diff --git a/tools/testing/selftests/kvm/memslot_modification_stress_test.c b/tools/testing/selftests/kvm/memslot_modification_stress_test.c
index 9c7578a098c3..3a1be9b75e01 100644
--- a/tools/testing/selftests/kvm/memslot_modification_stress_test.c
+++ b/tools/testing/selftests/kvm/memslot_modification_stress_test.c
@@ -83,21 +83,21 @@ struct test_params {
bool disable_slot_zap_quirk;
};
static void run_test(enum vm_guest_mode mode, void *arg)
{
struct test_params *p = arg;
struct kvm_vm *vm;
vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,
VM_MEM_SRC_ANONYMOUS,
- p->partition_vcpu_memory_access);
+ p->partition_vcpu_memory_access, 0);
#ifdef __x86_64__
if (p->disable_slot_zap_quirk)
vm_enable_cap(vm, KVM_CAP_DISABLE_QUIRKS2, KVM_X86_QUIRK_SLOT_ZAP_ALL);
pr_info("Memslot zap quirk %s\n", p->disable_slot_zap_quirk ?
"disabled" : "enabled");
#endif
pr_info("Finished creating vCPUs\n");
diff --git a/tools/testing/selftests/kvm/x86/dirty_log_page_splitting_test.c b/tools/testing/selftests/kvm/x86/dirty_log_page_splitting_test.c
index 388ba4101f97..661e9abfb439 100644
--- a/tools/testing/selftests/kvm/x86/dirty_log_page_splitting_test.c
+++ b/tools/testing/selftests/kvm/x86/dirty_log_page_splitting_test.c
@@ -94,21 +94,21 @@ static void run_test(enum vm_guest_mode mode, void *unused)
u64 pages_per_slot;
int i;
struct kvm_page_stats stats_populated;
struct kvm_page_stats stats_dirty_logging_enabled;
struct kvm_page_stats stats_dirty_pass[ITERATIONS];
struct kvm_page_stats stats_clear_pass[ITERATIONS];
struct kvm_page_stats stats_dirty_logging_disabled;
struct kvm_page_stats stats_repopulated;
vm = memstress_create_vm(mode, VCPUS, guest_percpu_mem_size,
- SLOTS, backing_src, false);
+ SLOTS, backing_src, false, 0);
guest_num_pages = (VCPUS * guest_percpu_mem_size) >> vm->page_shift;
guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
host_num_pages = vm_num_host_pages(mode, guest_num_pages);
pages_per_slot = host_num_pages / SLOTS;
TEST_ASSERT_EQ(host_num_pages, pages_per_slot * SLOTS);
TEST_ASSERT(!(host_num_pages % 512),
"Number of pages, '%lu' not a multiple of 2MiB", host_num_pages);
bitmaps = memstress_alloc_bitmaps(SLOTS, pages_per_slot);
--
2.54.0