Introduce a new selftest that loads an eBPF program that stores the
number of vmx exit counts per vcpu per vm. A process is created per
vm_create to load a separate eBPF program to collect its own stats
unique to the pid.
This test aims to serve as a proof-of-concept and example for using eBPF
to collect stats that are not provided by the other stats interfaces
such as kvm_binary_stats. Since there will be no further stats being
added to kvm_binary_stats, developers can use this selftest as a
reference for writing their own eBPF program + selftest to collect
whatever stat they may need for debugging/monitoring.
Signed-off-by: Kevin Cheng <chengkev@xxxxxxxxxx>
---
tools/testing/selftests/kvm/Makefile | 4 +-
tools/testing/selftests/kvm/build_ebpf.sh | 5 +
.../testing/selftests/kvm/kvm_vmx_exit_ebpf.c | 128 ++++++++++++++++++
.../selftests/kvm/kvm_vmx_exit_ebpf_kern.c | 74 ++++++++++
4 files changed, 210 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/kvm/build_ebpf.sh
create mode 100644 tools/testing/selftests/kvm/kvm_vmx_exit_ebpf.c
create mode 100644 tools/testing/selftests/kvm/kvm_vmx_exit_ebpf_kern.c
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 1750f91dd936..d9f56ccbc7bb 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -129,6 +129,7 @@ TEST_GEN_PROGS_x86_64 += set_memory_region_test
TEST_GEN_PROGS_x86_64 += steal_time
TEST_GEN_PROGS_x86_64 += kvm_binary_stats_test
TEST_GEN_PROGS_x86_64 += system_counter_offset_test
+TEST_GEN_PROGS_x86_64 += kvm_vmx_exit_ebpf
# Compiled outputs used by test targets
TEST_GEN_PROGS_EXTENDED_x86_64 += x86_64/nx_huge_pages_test
@@ -176,6 +177,7 @@ TEST_GEN_PROGS_riscv += set_memory_region_test
TEST_GEN_PROGS_riscv += kvm_binary_stats_test
TEST_PROGS += $(TEST_PROGS_$(ARCH_DIR))
+TEST_PROGS := build_ebpf.sh
TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(ARCH_DIR))
TEST_GEN_PROGS_EXTENDED += $(TEST_GEN_PROGS_EXTENDED_$(ARCH_DIR))
LIBKVM += $(LIBKVM_$(ARCH_DIR))
@@ -208,7 +210,7 @@ no-pie-option := $(call try-run, echo 'int main(void) { return 0; }' | \
pgste-option = $(call try-run, echo 'int main(void) { return 0; }' | \
$(CC) -Werror -Wl$(comma)--s390-pgste -x c - -o "$$TMP",-Wl$(comma)--s390-pgste)
-LDLIBS += -ldl
+LDLIBS += -ldl -L$(top_srcdir)/tools/lib/bpf -lbpf -lelf -lz
LDFLAGS += -pthread $(no-pie-option) $(pgste-option)
LIBKVM_C := $(filter %.c,$(LIBKVM))
diff --git a/tools/testing/selftests/kvm/build_ebpf.sh b/tools/testing/selftests/kvm/build_ebpf.sh
new file mode 100644
index 000000000000..b8038b0a0da5
--- /dev/null
+++ b/tools/testing/selftests/kvm/build_ebpf.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+clang -g -O2 -target bpf -D__TARGET_ARCH_x86_64 -I . -c kvm_vmx_exit_ebpf_kern.c
+ -o kvm_vmx_exit_ebpf_kern.o
+make -C ../../../lib/bpf || exit
diff --git a/tools/testing/selftests/kvm/kvm_vmx_exit_ebpf.c b/tools/testing/selftests/kvm/kvm_vmx_exit_ebpf.c
new file mode 100644
index 000000000000..a4bd2c549207
--- /dev/null
+++ b/tools/testing/selftests/kvm/kvm_vmx_exit_ebpf.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <bpf/bpf.h>
+#include <../bpf/libbpf.h>
+#include <linux/btf.h>
+
+#include "test_util.h"
+
+#include "kvm_util.h"
+#include "linux/kvm.h"
+
+#define VCPU_ID 0
+
+struct stats_map_key {
+ __u32 pid;
+ __u32 vcpu_id;
+ __u32 exit_reason;
+};
+
+static void guest_code(void)
+{
+ __asm__ __volatile__("cpuid");
+}
+
+int main(int argc, char **argv)
+{
+ if (argc < 2) {
+ fprintf(stderr, "Expected arguments: <number_of_vms>\n");
+ return EXIT_FAILURE;
+ }
+ int n = atoi(argv[1]);
+
+ for (int i = 0; i < n; i++) {
+ if (fork() == 0) {
+ struct kvm_vm *vm;
+ struct kvm_vcpu *vcpu;
+
+ vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+
+ // BPF userspace code
+ struct bpf_object *obj;
+ struct bpf_program *prog;
+ struct bpf_map *map_obj;
+ struct bpf_link *link = NULL;
+
+ obj = bpf_object__open_file("kvm_vmx_exit_ebpf_kern.o", NULL);
+ if (libbpf_get_error(obj)) {
+ fprintf(stderr, "ERROR: opening BPF object file failed\n");
+ return 0;
+ }
+
+ map_obj = bpf_object__find_map_by_name(obj, "vmx_exit_map");
+ if (!map_obj) {
+ fprintf(stderr, "ERROR: loading of vmx BPF map failed\n");
+ goto cleanup;
+ }
+
+ struct bpf_map *pid_map = bpf_object__find_map_by_name(obj, "pid_map");
+
+ if (!pid_map) {
+ fprintf(stderr, "ERROR: loading of pid BPF map failed\n");
+ goto cleanup;
+ }
+
+ /* load BPF program */
+ if (bpf_object__load(obj)) {
+ fprintf(stderr, "ERROR: loading BPF object file failed\n");
+ goto cleanup;
+ }
+
+ __u32 userspace_pid = (__u32)getpid();
+ __u32 val = (__u32)getpid();
+
+ bpf_map_update_elem(bpf_map__fd(pid_map), &userspace_pid, &val, 0);
+
+ prog = bpf_object__find_program_by_name(obj, "bpf_exit_prog");
+ if (libbpf_get_error(prog)) {
+ fprintf(stderr, "ERROR: finding a prog in obj file failed\n");
+ goto cleanup;
+ }
+
+ link = bpf_program__attach(prog);
+ if (libbpf_get_error(link)) {
+ fprintf(stderr, "ERROR: bpf_program__attach failed\n");
+ link = NULL;
+ goto cleanup;
+ }
+
+ for (int j = 0; j < 10000; j++)
+ vcpu_run(vcpu);
+
+ struct stats_map_key key = {
+ .pid = 0,
+ .vcpu_id = 0,
+ .exit_reason = 18,
+ };
+
+
+ struct stats_map_key next_key, lookup_key;
+
+ lookup_key = key;
+ while (bpf_map_get_next_key(bpf_map__fd(map_obj), &lookup_key, &next_key)
+ == 0) {
+ int count;
+
+ bpf_map_lookup_elem(bpf_map__fd(map_obj), &next_key, &count);
+ fprintf(stdout, "exit reason: '%d'\ncount: %d\npid: %d\n",
+ next_key.exit_reason, count, next_key.pid);
+ lookup_key = next_key;
+ }
+
+cleanup:
+ bpf_link__destroy(link);
+ bpf_object__close(obj);
+ kvm_vm_free(vm);
+ }
+ }
+
+ for (int i = 0; i < n; i++)
+ wait(NULL);
+ return 0;
+}
diff --git a/tools/testing/selftests/kvm/kvm_vmx_exit_ebpf_kern.c b/tools/testing/selftests/kvm/kvm_vmx_exit_ebpf_kern.c
new file mode 100644
index 000000000000..b9c076f93171
--- /dev/null
+++ b/tools/testing/selftests/kvm/kvm_vmx_exit_ebpf_kern.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/bpf.h>
+#include <stdint.h>
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+#include <bpf/bpf_core_read.h>
+
+struct kvm_vcpu {
+ int vcpu_id;
+};
+
+struct vmx_args {
+ __u64 pad;
+ unsigned int exit_reason;
+ __u32 isa;
+ struct kvm_vcpu *vcpu;
+};
+
+struct stats_map_key {
+ __u32 pid;
+ __u32 vcpu_id;
+ __u32 exit_reason;
+};
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 1024);
+ __type(key, struct stats_map_key);
+ __type(value, int);
+} vmx_exit_map SEC(".maps");
+
+struct {
+ __uint(type, BPF_MAP_TYPE_HASH);
+ __uint(max_entries, 1);
+ __type(key, __u32);
+ __type(value, __u32);
+} pid_map SEC(".maps");
+
+
+SEC("tracepoint/kvm/kvm_exit")
+int bpf_exit_prog(struct vmx_args *ctx)
+{
+ __u32 curr_pid = (bpf_get_current_pid_tgid() >> 32);
+
+ __u32 *userspace_pid = bpf_map_lookup_elem(&pid_map, &curr_pid);
+
+ if (!userspace_pid || *userspace_pid != curr_pid)
+ return 0;
+
+ struct kvm_vcpu *vcpu = ctx->vcpu;
+ int _vcpu_id = BPF_CORE_READ(vcpu, vcpu_id);
+
+ struct stats_map_key key = {
+ .pid = (bpf_get_current_pid_tgid() >> 32),
+ .vcpu_id = _vcpu_id,
+ .exit_reason = ctx->exit_reason,
+ };
+
+ int *value = bpf_map_lookup_elem(&vmx_exit_map, &key);
+
+ if (value) {
+ *value = *value + 1;
+ bpf_map_update_elem(&vmx_exit_map, &key, value, BPF_ANY);
+ } else {
+ int temp = 1;
+
+ bpf_map_update_elem(&vmx_exit_map, &key, &temp, BPF_ANY);
+ }
+
+ return 0;
+}
+
+char _license[] SEC("license") = "GPL";
--
2.39.1.456.gfc5497dd1b-goog
