[PATCH 1/5] KVM: selftests: Factor code out of demand_paging_test

Ben Gardon
2020-10-28T01:48:31Z

Much of the code in demand_paging_test can be reused by other, similar
multi-vCPU-memory-touching-perfromance-tests. Factor that common code
out for reuse.

No functional change expected.

This series was tested by running the following invocations on an Intel
Skylake machine:
dirty_log_perf_test -b 20m -i 100 -v 64
dirty_log_perf_test -b 20g -i 5 -v 4
dirty_log_perf_test -b 4g -i 5 -v 32
demand_paging_test -b 20m -v 64
demand_paging_test -b 20g -v 4
demand_paging_test -b 4g -v 32
All behaved as expected.

Signed-off-by: Ben Gardon <bgardon@google.com>
---
.../selftests/kvm/demand_paging_test.c | 204 ++----------------
.../selftests/kvm/include/perf_test_util.h | 187 ++++++++++++++++
2 files changed, 210 insertions(+), 181 deletions(-)
create mode 100644 tools/testing/selftests/kvm/include/perf_test_util.h

diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 360cd3ea4cd67..4251e98ceb69f 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -21,18 +21,12 @@
#include <linux/bitops.h>
#include <linux/userfaultfd.h>

-#include "test_util.h"
-#include "kvm_util.h"
+#include "perf_test_util.h"
#include "processor.h"
+#include "test_util.h"

#ifdef __NR_userfaultfd

-/* The memory slot index demand page */
-#define TEST_MEM_SLOT_INDEX 1
-
-/* Default guest test virtual memory offset */
-#define DEFAULT_GUEST_TEST_MEM 0xc0000000
-
#define DEFAULT_GUEST_TEST_MEM_SIZE (1 << 30) /* 1G */

#ifdef PRINT_PER_PAGE_UPDATES
@@ -47,75 +41,14 @@
#define PER_VCPU_DEBUG(...) _no_printf(__VA_ARGS__)
#endif

-#define MAX_VCPUS 512
-
-/*
- * Guest/Host shared variables. Ensure addr_gva2hva() and/or
- * sync_global_to/from_guest() are used when accessing from
- * the host. READ/WRITE_ONCE() should also be used with anything
- * that may change.
- */
-static uint64_t host_page_size;
-static uint64_t guest_page_size;
-
static char *guest_data_prototype;

-/*
- * Guest physical memory offset of the testing memory slot.
- * This will be set to the topmost valid physical address minus
- * the test memory size.
- */
-static uint64_t guest_test_phys_mem;
-
-/*
- * Guest virtual memory offset of the testing memory slot.
- * Must not conflict with identity mapped test code.
- */
-static uint64_t guest_test_virt_mem = DEFAULT_GUEST_TEST_MEM;
-
-struct vcpu_args {
- uint64_t gva;
- uint64_t pages;
-
- /* Only used by the host userspace part of the vCPU thread */
- int vcpu_id;
- struct kvm_vm *vm;
-};
-
-static struct vcpu_args vcpu_args[MAX_VCPUS];
-
-/*
- * Continuously write to the first 8 bytes of each page in the demand paging
- * memory region.
- */
-static void guest_code(uint32_t vcpu_id)
-{
- uint64_t gva;
- uint64_t pages;
- int i;
-
- /* Make sure vCPU args data structure is not corrupt. */
- GUEST_ASSERT(vcpu_args[vcpu_id].vcpu_id == vcpu_id);
-
- gva = vcpu_args[vcpu_id].gva;
- pages = vcpu_args[vcpu_id].pages;
-
- for (i = 0; i < pages; i++) {
- uint64_t addr = gva + (i * guest_page_size);
-
- addr &= ~(host_page_size - 1);
- *(uint64_t *)addr = 0x0123456789ABCDEF;
- }
-
- GUEST_SYNC(1);
-}
-
static void *vcpu_worker(void *data)
{
int ret;
- struct vcpu_args *args = (struct vcpu_args *)data;
- struct kvm_vm *vm = args->vm;
- int vcpu_id = args->vcpu_id;
+ struct vcpu_args *vcpu_args = (struct vcpu_args *)data;
+ int vcpu_id = vcpu_args->vcpu_id;
+ struct kvm_vm *vm = perf_test_args.vm;
struct kvm_run *run;
struct timespec start, end, ts_diff;

@@ -141,39 +74,6 @@ static void *vcpu_worker(void *data)
return NULL;
}

-#define PAGE_SHIFT_4K 12
-#define PTES_PER_4K_PT 512
-
-static struct kvm_vm *create_vm(enum vm_guest_mode mode, int vcpus,
- uint64_t vcpu_memory_bytes)
-{
- struct kvm_vm *vm;
- uint64_t pages = DEFAULT_GUEST_PHY_PAGES;
-
- /* Account for a few pages per-vCPU for stacks */
- pages += DEFAULT_STACK_PGS * vcpus;
-
- /*
- * Reserve twice the ammount of memory needed to map the test region and
- * the page table / stacks region, at 4k, for page tables. Do the
- * calculation with 4K page size: the smallest of all archs. (e.g., 64K
- * page size guest will need even less memory for page tables).
- */
- pages += (2 * pages) / PTES_PER_4K_PT;
- pages += ((2 * vcpus * vcpu_memory_bytes) >> PAGE_SHIFT_4K) /
- PTES_PER_4K_PT;
- pages = vm_adjust_num_guest_pages(mode, pages);
-
- pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
-
- vm = _vm_create(mode, pages, O_RDWR);
- kvm_vm_elf_load(vm, program_invocation_name, 0, 0);
-#ifdef __x86_64__
- vm_create_irqchip(vm);
-#endif
- return vm;
-}
-
static int handle_uffd_page_request(int uffd, uint64_t addr)
{
pid_t tid;
@@ -186,7 +86,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)

copy.src = (uint64_t)guest_data_prototype;
copy.dst = addr;
- copy.len = host_page_size;
+ copy.len = perf_test_args.host_page_size;
copy.mode = 0;

clock_gettime(CLOCK_MONOTONIC, &start);
@@ -203,7 +103,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)
PER_PAGE_DEBUG("UFFDIO_COPY %d \t%ld ns\n", tid,
timespec_to_ns(timespec_sub(end, start)));
PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",
- host_page_size, addr, tid);
+ perf_test_args.host_page_size, addr, tid);

return 0;
}
@@ -360,64 +260,21 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
struct timespec start, end, ts_diff;
int *pipefds = NULL;
struct kvm_vm *vm;
- uint64_t guest_num_pages;
int vcpu_id;
int r;

vm = create_vm(mode, vcpus, vcpu_memory_bytes);

- guest_page_size = vm_get_page_size(vm);
-
- TEST_ASSERT(vcpu_memory_bytes % guest_page_size == 0,
- "Guest memory size is not guest page size aligned.");
-
- guest_num_pages = (vcpus * vcpu_memory_bytes) / guest_page_size;
- guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
-
- /*
- * If there should be more memory in the guest test region than there
- * can be pages in the guest, it will definitely cause problems.
- */
- TEST_ASSERT(guest_num_pages < vm_get_max_gfn(vm),
- "Requested more guest memory than address space allows.\n"
- " guest pages: %lx max gfn: %x vcpus: %d wss: %lx]\n",
- guest_num_pages, vm_get_max_gfn(vm), vcpus,
- vcpu_memory_bytes);
-
- host_page_size = getpagesize();
- TEST_ASSERT(vcpu_memory_bytes % host_page_size == 0,
- "Guest memory size is not host page size aligned.");
-
- guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) *
- guest_page_size;
- guest_test_phys_mem &= ~(host_page_size - 1);
-
-#ifdef __s390x__
- /* Align to 1M (segment size) */
- guest_test_phys_mem &= ~((1 << 20) - 1);
-#endif
-
- pr_info("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
-
- /* Add an extra memory slot for testing demand paging */
- vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
- guest_test_phys_mem,
- TEST_MEM_SLOT_INDEX,
- guest_num_pages, 0);
-
- /* Do mapping for the demand paging memory slot */
- virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, guest_num_pages, 0);
-
- ucall_init(vm, NULL);
-
- guest_data_prototype = malloc(host_page_size);
+ guest_data_prototype = malloc(perf_test_args.host_page_size);
TEST_ASSERT(guest_data_prototype,
"Failed to allocate buffer for guest data pattern");
- memset(guest_data_prototype, 0xAB, host_page_size);
+ memset(guest_data_prototype, 0xAB, perf_test_args.host_page_size);

vcpu_threads = malloc(vcpus * sizeof(*vcpu_threads));
TEST_ASSERT(vcpu_threads, "Memory allocation failed");

+ add_vcpus(vm, vcpus, vcpu_memory_bytes);
+
if (use_uffd) {
uffd_handler_threads =
malloc(vcpus * sizeof(*uffd_handler_threads));
@@ -428,22 +285,18 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,

pipefds = malloc(sizeof(int) * vcpus * 2);
TEST_ASSERT(pipefds, "Unable to allocate memory for pipefd");
- }

- for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
- vm_paddr_t vcpu_gpa;
- void *vcpu_hva;
-
- vm_vcpu_add_default(vm, vcpu_id, guest_code);
+ for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
+ vm_paddr_t vcpu_gpa;
+ void *vcpu_hva;

- vcpu_gpa = guest_test_phys_mem + (vcpu_id * vcpu_memory_bytes);
- PER_VCPU_DEBUG("Added VCPU %d with test mem gpa [%lx, %lx)\n",
- vcpu_id, vcpu_gpa, vcpu_gpa + vcpu_memory_bytes);
+ vcpu_gpa = guest_test_phys_mem + (vcpu_id * vcpu_memory_bytes);
+ PER_VCPU_DEBUG("Added VCPU %d with test mem gpa [%lx, %lx)\n",
+ vcpu_id, vcpu_gpa, vcpu_gpa + vcpu_memory_bytes);

- /* Cache the HVA pointer of the region */
- vcpu_hva = addr_gpa2hva(vm, vcpu_gpa);
+ /* Cache the HVA pointer of the region */
+ vcpu_hva = addr_gpa2hva(vm, vcpu_gpa);

- if (use_uffd) {
/*
* Set up user fault fd to handle demand paging
* requests.
@@ -460,22 +313,10 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
if (r < 0)
exit(-r);
}
-
-#ifdef __x86_64__
- vcpu_set_cpuid(vm, vcpu_id, kvm_get_supported_cpuid());
-#endif
-
- vcpu_args[vcpu_id].vm = vm;
- vcpu_args[vcpu_id].vcpu_id = vcpu_id;
- vcpu_args[vcpu_id].gva = guest_test_virt_mem +
- (vcpu_id * vcpu_memory_bytes);
- vcpu_args[vcpu_id].pages = vcpu_memory_bytes / guest_page_size;
}

/* Export the shared variables to the guest */
- sync_global_to_guest(vm, host_page_size);
- sync_global_to_guest(vm, guest_page_size);
- sync_global_to_guest(vm, vcpu_args);
+ sync_global_to_guest(vm, perf_test_args);

pr_info("Finished creating vCPUs and starting uffd threads\n");

@@ -483,7 +324,7 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,

for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker,
- &vcpu_args[vcpu_id]);
+ &perf_test_args.vcpu_args[vcpu_id]);
}

pr_info("Started all vCPUs\n");
@@ -514,7 +355,8 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
pr_info("Total guest execution time: %ld.%.9lds\n",
ts_diff.tv_sec, ts_diff.tv_nsec);
pr_info("Overall demand paging rate: %f pgs/sec\n",
- guest_num_pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
+ perf_test_args.vcpu_args[0].pages * vcpus /
+ ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));

ucall_uninit(vm);
kvm_vm_free(vm);
diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h
new file mode 100644
index 0000000000000..f71f0858a1f29
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/perf_test_util.h
@@ -0,0 +1,187 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * tools/testing/selftests/kvm/include/perf_test_util.h
+ *
+ * Copyright (C) 2020, Google LLC.
+ */
+
+#ifndef SELFTEST_KVM_PERF_TEST_UTIL_H
+#define SELFTEST_KVM_PERF_TEST_UTIL_H
+
+#include "kvm_util.h"
+#include "processor.h"
+
+#define MAX_VCPUS 512
+
+#define PAGE_SHIFT_4K 12
+#define PTES_PER_4K_PT 512
+
+#define TEST_MEM_SLOT_INDEX 1
+
+/* Default guest test virtual memory offset */
+#define DEFAULT_GUEST_TEST_MEM 0xc0000000
+
+/*
+ * Guest physical memory offset of the testing memory slot.
+ * This will be set to the topmost valid physical address minus
+ * the test memory size.
+ */
+static uint64_t guest_test_phys_mem;
+
+/*
+ * Guest virtual memory offset of the testing memory slot.
+ * Must not conflict with identity mapped test code.
+ */
+static uint64_t guest_test_virt_mem = DEFAULT_GUEST_TEST_MEM;
+
+struct vcpu_args {
+ uint64_t gva;
+ uint64_t pages;
+
+ /* Only used by the host userspace part of the vCPU thread */
+ int vcpu_id;
+};
+
+struct perf_test_args {
+ struct kvm_vm *vm;
+ uint64_t host_page_size;
+ uint64_t guest_page_size;
+
+ struct vcpu_args vcpu_args[MAX_VCPUS];
+};
+
+static struct perf_test_args perf_test_args;
+
+/*
+ * Continuously write to the first 8 bytes of each page in the
+ * specified region.
+ */
+static void guest_code(uint32_t vcpu_id)
+{
+ struct vcpu_args *vcpu_args = &perf_test_args.vcpu_args[vcpu_id];
+ uint64_t gva;
+ uint64_t pages;
+ int i;
+
+ /* Make sure vCPU args data structure is not corrupt. */
+ GUEST_ASSERT(vcpu_args->vcpu_id == vcpu_id);
+
+ gva = vcpu_args->gva;
+ pages = vcpu_args->pages;
+
+ for (i = 0; i < pages; i++) {
+ uint64_t addr = gva + (i * perf_test_args.guest_page_size);
+
+ addr &= ~(perf_test_args.host_page_size - 1);
+ *(uint64_t *)addr = 0x0123456789ABCDEF;
+ }
+
+ GUEST_SYNC(1);
+}
+
+static struct kvm_vm *create_vm(enum vm_guest_mode mode, int vcpus,
+ uint64_t vcpu_memory_bytes)
+{
+ struct kvm_vm *vm;
+ uint64_t pages = DEFAULT_GUEST_PHY_PAGES;
+ uint64_t guest_num_pages;
+
+ /* Account for a few pages per-vCPU for stacks */
+ pages += DEFAULT_STACK_PGS * vcpus;
+
+ /*
+ * Reserve twice the ammount of memory needed to map the test region and
+ * the page table / stacks region, at 4k, for page tables. Do the
+ * calculation with 4K page size: the smallest of all archs. (e.g., 64K
+ * page size guest will need even less memory for page tables).
+ */
+ pages += (2 * pages) / PTES_PER_4K_PT;
+ pages += ((2 * vcpus * vcpu_memory_bytes) >> PAGE_SHIFT_4K) /
+ PTES_PER_4K_PT;
+ pages = vm_adjust_num_guest_pages(mode, pages);
+
+ pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
+
+ vm = _vm_create(mode, pages, O_RDWR);
+ kvm_vm_elf_load(vm, program_invocation_name, 0, 0);
+#ifdef __x86_64__
+ vm_create_irqchip(vm);
+#endif
+
+ perf_test_args.vm = vm;
+ perf_test_args.guest_page_size = vm_get_page_size(vm);
+ perf_test_args.host_page_size = getpagesize();
+
+ TEST_ASSERT(vcpu_memory_bytes % perf_test_args.guest_page_size == 0,
+ "Guest memory size is not guest page size aligned.");
+
+ guest_num_pages = (vcpus * vcpu_memory_bytes) /
+ perf_test_args.guest_page_size;
+ guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
+
+ /*
+ * If there should be more memory in the guest test region than there
+ * can be pages in the guest, it will definitely cause problems.
+ */
+ TEST_ASSERT(guest_num_pages < vm_get_max_gfn(vm),
+ "Requested more guest memory than address space allows.\n"
+ " guest pages: %lx max gfn: %x vcpus: %d wss: %lx]\n",
+ guest_num_pages, vm_get_max_gfn(vm), vcpus,
+ vcpu_memory_bytes);
+
+ TEST_ASSERT(vcpu_memory_bytes % perf_test_args.host_page_size == 0,
+ "Guest memory size is not host page size aligned.");
+
+ guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) *
+ perf_test_args.guest_page_size;
+ guest_test_phys_mem &= ~(perf_test_args.host_page_size - 1);
+
+#ifdef __s390x__
+ /* Align to 1M (segment size) */
+ guest_test_phys_mem &= ~((1 << 20) - 1);
+#endif
+
+ pr_info("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
+
+ /* Add an extra memory slot for testing */
+ vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
+ guest_test_phys_mem,
+ TEST_MEM_SLOT_INDEX,
+ guest_num_pages, 0);
+
+ /* Do mapping for the demand paging memory slot */
+ virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, guest_num_pages, 0);
+
+ ucall_init(vm, NULL);
+
+ return vm;
+}
+
+static void add_vcpus(struct kvm_vm *vm, int vcpus, uint64_t vcpu_memory_bytes)
+{
+ vm_paddr_t vcpu_gpa;
+ struct vcpu_args *vcpu_args;
+ int vcpu_id;
+
+ for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
+ vcpu_args = &perf_test_args.vcpu_args[vcpu_id];
+
+ vm_vcpu_add_default(vm, vcpu_id, guest_code);
+
+#ifdef __x86_64__
+ vcpu_set_cpuid(vm, vcpu_id, kvm_get_supported_cpuid());
+#endif
+
+ vcpu_args->vcpu_id = vcpu_id;
+ vcpu_args->gva = guest_test_virt_mem +
+ (vcpu_id * vcpu_memory_bytes);
+ vcpu_args->pages = vcpu_memory_bytes /
+ perf_test_args.guest_page_size;
+
+ vcpu_gpa = guest_test_phys_mem + (vcpu_id * vcpu_memory_bytes);
+ pr_debug("Added VCPU %d with test mem gpa [%lx, %lx)\n",
+ vcpu_id, vcpu_gpa, vcpu_gpa + vcpu_memory_bytes);
+ }
+}
+
+#endif /* SELFTEST_KVM_PERF_TEST_UTIL_H */
--
2.29.0.rc2.309.g374f81d7ae-goog