Introduce a new selftest, execute_perf_test, that uses the
perf_test_util framework to measure the performance of executing code
within a VM. This test is similar to the other perf_test_util-based
tests in that it spins up a variable number of vCPUs and runs them
concurrently, accessing memory.
In order to support executiong, extend perf_test_util to populate guest
memory with return instructions rather than random garbage. This way
memory can be execute simply by calling it.
Currently only x86-64 supports execution, but other architectures can be
easily added by providing their return code instruction.
Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
---
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../testing/selftests/kvm/execute_perf_test.c | 188 ++++++++++++++++++
.../selftests/kvm/include/perf_test_util.h | 2 +
.../selftests/kvm/lib/perf_test_util.c | 25 ++-
5 files changed, 215 insertions(+), 2 deletions(-)
create mode 100644 tools/testing/selftests/kvm/execute_perf_test.c
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 1f1b6c978bf7..3647ddacb103 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -56,6 +56,7 @@
/demand_paging_test
/dirty_log_test
/dirty_log_perf_test
+/execute_perf_test
/hardware_disable_test
/kvm_create_max_vcpus
/kvm_page_table_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c9cdbd248727..3c67346b0766 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -92,6 +92,7 @@ TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
TEST_GEN_PROGS_x86_64 += demand_paging_test
TEST_GEN_PROGS_x86_64 += dirty_log_test
TEST_GEN_PROGS_x86_64 += dirty_log_perf_test
+TEST_GEN_PROGS_x86_64 += execute_perf_test
TEST_GEN_PROGS_x86_64 += hardware_disable_test
TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
TEST_GEN_PROGS_x86_64 += kvm_page_table_test
diff --git a/tools/testing/selftests/kvm/execute_perf_test.c b/tools/testing/selftests/kvm/execute_perf_test.c
new file mode 100644
index 000000000000..fa78facf44e7
--- /dev/null
+++ b/tools/testing/selftests/kvm/execute_perf_test.c
@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <inttypes.h>
+#include <limits.h>
+#include <pthread.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "kvm_util.h"
+#include "test_util.h"
+#include "perf_test_util.h"
+#include "guest_modes.h"
+
+/* Global variable used to synchronize all of the vCPU threads. */
+static int iteration;
+
+/* Set to true when vCPU threads should exit. */
+static bool done;
+
+/* The iteration that was last completed by each vCPU. */
+static int vcpu_last_completed_iteration[KVM_MAX_VCPUS];
+
+/* Whether to overlap the regions of memory vCPUs access. */
+static bool overlap_memory_access;
+
+struct test_params {
+ /* The backing source for the region of memory. */
+ enum vm_mem_backing_src_type backing_src;
+
+ /* The amount of memory to allocate for each vCPU. */
+ uint64_t vcpu_memory_bytes;
+
+ /* The number of vCPUs to create in the VM. */
+ int vcpus;
+};
+
+static void assert_ucall(struct kvm_vm *vm, uint32_t vcpu_id,
+ uint64_t expected_ucall)
+{
+ struct ucall uc;
+ uint64_t actual_ucall = get_ucall(vm, vcpu_id, &uc);
+
+ TEST_ASSERT(expected_ucall == actual_ucall,
+ "Guest exited unexpectedly (expected ucall %" PRIu64
+ ", got %" PRIu64 ")",
+ expected_ucall, actual_ucall);
+}
+
+static bool spin_wait_for_next_iteration(int *current_iteration)
+{
+ int last_iteration = *current_iteration;
+
+ do {
+ if (READ_ONCE(done))
+ return false;
+
+ *current_iteration = READ_ONCE(iteration);
+ } while (last_iteration == *current_iteration);
+
+ return true;
+}
+
+static void vcpu_thread_main(struct perf_test_vcpu_args *vcpu_args)
+{
+ struct kvm_vm *vm = perf_test_args.vm;
+ int vcpu_id = vcpu_args->vcpu_id;
+ int current_iteration = 0;
+
+ while (spin_wait_for_next_iteration(¤t_iteration)) {
+ vcpu_run(vm, vcpu_id);
+ assert_ucall(vm, vcpu_id, UCALL_SYNC);
+ vcpu_last_completed_iteration[vcpu_id] = current_iteration;
+ }
+}
+
+static void spin_wait_for_vcpu(int vcpu_id, int target_iteration)
+{
+ while (READ_ONCE(vcpu_last_completed_iteration[vcpu_id]) !=
+ target_iteration) {
+ continue;
+ }
+}
+
+static void run_iteration(struct kvm_vm *vm, int vcpus, const char *description)
+{
+ struct timespec ts_start;
+ struct timespec ts_elapsed;
+ int next_iteration;
+ int vcpu_id;
+
+ /* Kick off the vCPUs by incrementing iteration. */
+ next_iteration = ++iteration;
+
+ clock_gettime(CLOCK_MONOTONIC, &ts_start);
+
+ /* Wait for all vCPUs to finish the iteration. */
+ for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++)
+ spin_wait_for_vcpu(vcpu_id, next_iteration);
+
+ ts_elapsed = timespec_elapsed(ts_start);
+ pr_info("%-30s: %ld.%09lds\n",
+ description, ts_elapsed.tv_sec, ts_elapsed.tv_nsec);
+}
+
+static void run_test(enum vm_guest_mode mode, void *arg)
+{
+ struct test_params *params = arg;
+ struct kvm_vm *vm;
+ int vcpus = params->vcpus;
+
+ vm = perf_test_create_vm(mode, vcpus, params->vcpu_memory_bytes, 1,
+ params->backing_src, !overlap_memory_access);
+
+ perf_test_start_vcpu_threads(vcpus, vcpu_thread_main);
+
+ pr_info("\n");
+
+ perf_test_set_wr_fract(vm, 1);
+ run_iteration(vm, vcpus, "Populating memory");
+
+ perf_test_set_execute(vm, true);
+ run_iteration(vm, vcpus, "Executing from memory");
+
+ /* Set done to signal the vCPU threads to exit */
+ done = true;
+
+ perf_test_join_vcpu_threads(vcpus);
+ perf_test_destroy_vm(vm);
+}
+
+static void help(char *name)
+{
+ puts("");
+ printf("usage: %s [-h] [-m mode] [-b vcpu_bytes] [-v vcpus] [-o] [-s mem_type]\n",
+ name);
+ puts("");
+ printf(" -h: Display this help message.");
+ guest_modes_help();
+ printf(" -b: specify the size of the memory region which should be\n"
+ " dirtied by each vCPU. e.g. 10M or 3G.\n"
+ " (default: 1G)\n");
+ printf(" -v: specify the number of vCPUs to run.\n");
+ printf(" -o: Overlap guest memory accesses instead of partitioning\n"
+ " them into a separate region of memory for each vCPU.\n");
+ backing_src_help("-s");
+ puts("");
+ exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+ struct test_params params = {
+ .backing_src = DEFAULT_VM_MEM_SRC,
+ .vcpu_memory_bytes = DEFAULT_PER_VCPU_MEM_SIZE,
+ .vcpus = 1,
+ };
+ int opt;
+
+ guest_modes_append_default();
+
+ while ((opt = getopt(argc, argv, "hm:b:v:os:")) != -1) {
+ switch (opt) {
+ case 'm':
+ guest_modes_cmdline(optarg);
+ break;
+ case 'b':
+ params.vcpu_memory_bytes = parse_size(optarg);
+ break;
+ case 'v':
+ params.vcpus = atoi(optarg);
+ break;
+ case 'o':
+ overlap_memory_access = true;
+ break;
+ case 's':
+ params.backing_src = parse_backing_src_type(optarg);
+ break;
+ case 'h':
+ default:
+ help(argv[0]);
+ break;
+ }
+ }
+
+ for_each_guest_mode(run_test, ¶ms);
+
+ return 0;
+}
diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h
index a86f953d8d36..0a5a56539aff 100644
--- a/tools/testing/selftests/kvm/include/perf_test_util.h
+++ b/tools/testing/selftests/kvm/include/perf_test_util.h
@@ -33,6 +33,7 @@ struct perf_test_args {
uint64_t gpa;
uint64_t guest_page_size;
int wr_fract;
+ bool execute;
struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS];
};
@@ -46,6 +47,7 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int vcpus,
void perf_test_destroy_vm(struct kvm_vm *vm);
void perf_test_set_wr_fract(struct kvm_vm *vm, int wr_fract);
+void perf_test_set_execute(struct kvm_vm *vm, bool execute);
void perf_test_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct perf_test_vcpu_args *));
void perf_test_join_vcpu_threads(int vcpus);
diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
index 722df3a28791..1a5eb60b59da 100644
--- a/tools/testing/selftests/kvm/lib/perf_test_util.c
+++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
@@ -36,6 +36,16 @@ static void (*vcpu_thread_fn)(struct perf_test_vcpu_args *);
/* Set to true once all vCPU threads are up and running. */
static bool all_vcpu_threads_running;
+/*
+ * When writing to guest memory, write the opcode for the `ret` instruction so
+ * that subsequent iteractions can exercise instruction fetch by calling the
+ * memory.
+ *
+ * NOTE: Non-x86 architectures would to use different values here to support
+ * execute.
+ */
+#define RETURN_OPCODE 0xC3
+
/*
* Continuously write to the first 8 bytes of each page in the
* specified region.
@@ -58,8 +68,10 @@ static void guest_code(uint32_t vcpu_id)
for (i = 0; i < pages; i++) {
uint64_t addr = gva + (i * pta->guest_page_size);
- if (i % pta->wr_fract == 0)
- *(uint64_t *)addr = 0x0123456789ABCDEF;
+ if (pta->execute)
+ ((void (*)(void)) addr)();
+ else if (i % pta->wr_fract == 0)
+ *(uint64_t *)addr = RETURN_OPCODE;
else
READ_ONCE(*(uint64_t *)addr);
}
@@ -198,6 +210,15 @@ void perf_test_set_wr_fract(struct kvm_vm *vm, int wr_fract)
sync_global_to_guest(vm, perf_test_args);
}
+void perf_test_set_execute(struct kvm_vm *vm, bool execute)
+{
+#ifndef __x86_64__
+ TEST_ASSERT(false, "Execute not supported on this architure; see RETURN_OPCODE.");
+#endif
+ perf_test_args.execute = execute;
+ sync_global_to_guest(vm, perf_test_args);
+}
+
static void *vcpu_thread_main(void *data)
{
struct vcpu_thread *vcpu = data;
base-commit: d1fb6a1ca3e535f89628193ab94203533b264c8c
--
2.35.1.1094.g7c7d902a7c-goog
