On 13/02/21 01:14, Marc Orr wrote:
From: Ignacio Alvarado <[email protected]>

This test launches 512 VMs in serial and kills them after a random
amount of time.

The test was original written to exercise KVM user notifiers in
the context of1650b4ebc99d:
- KVM: Disable irq while unregistering user notifier
- 
https://lore.kernel.org/kvm/CACXrx53vkO=hkfwwwk+fvpvxcnjprymtdz10qwxfvvx_ptg...@mail.gmail.com/

Recently, this test piqued my interest because it proved useful to
for AMD SNP in exercising the "in-use" pages, described in APM section
15.36.12, "Running SNP-Active Virtual Machines".

To run the test, first compile:
$ make "CPPFLAGS=-static -Wl,--whole-archive -lpthread -Wl,--no-whole-archive" \
     -C tools/testing/selftests/kvm/

Then, copy the test over to a machine with the kernel and run:
$ ./hardware_disable_test

Queued, but these two paragraphs do not belong in an upstream commit message. Thanks!

Paolo

Signed-off-by: Ignacio Alvarado <[email protected]>
Signed-off-by: Marc Orr <[email protected]>
---
  tools/testing/selftests/kvm/.gitignore        |   1 +
  tools/testing/selftests/kvm/Makefile          |   1 +
  .../selftests/kvm/hardware_disable_test.c     | 165 ++++++++++++++++++
  3 files changed, 167 insertions(+)
  create mode 100644 tools/testing/selftests/kvm/hardware_disable_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore 
b/tools/testing/selftests/kvm/.gitignore
index ce8f4ad39684..d631e111441a 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -28,6 +28,7 @@
  /demand_paging_test
  /dirty_log_test
  /dirty_log_perf_test
+/hardware_disable_test
  /kvm_create_max_vcpus
  /set_memory_region_test
  /steal_time
diff --git a/tools/testing/selftests/kvm/Makefile 
b/tools/testing/selftests/kvm/Makefile
index fe41c6a0fa67..c1c403d878f6 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -62,6 +62,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/tsc_msrs_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 += hardware_disable_test
  TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
  TEST_GEN_PROGS_x86_64 += set_memory_region_test
  TEST_GEN_PROGS_x86_64 += steal_time
diff --git a/tools/testing/selftests/kvm/hardware_disable_test.c 
b/tools/testing/selftests/kvm/hardware_disable_test.c
new file mode 100644
index 000000000000..2f2eeb8a1d86
--- /dev/null
+++ b/tools/testing/selftests/kvm/hardware_disable_test.c
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * This test is intended to reproduce a crash that happens when
+ * kvm_arch_hardware_disable is called and it attempts to unregister the user
+ * return notifiers.
+ */
+
+#define _GNU_SOURCE
+
+#include <fcntl.h>
+#include <pthread.h>
+#include <semaphore.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+#include <test_util.h>
+
+#include "kvm_util.h"
+
+#define VCPU_NUM 4
+#define SLEEPING_THREAD_NUM (1 << 4)
+#define FORK_NUM (1ULL << 9)
+#define DELAY_US_MAX 2000
+#define GUEST_CODE_PIO_PORT 4
+
+sem_t *sem;
+
+/* Arguments for the pthreads */
+struct payload {
+       struct kvm_vm *vm;
+       uint32_t index;
+};
+
+static void guest_code(void)
+{
+       for (;;)
+               ;  /* Some busy work */
+       printf("Should not be reached.\n");
+}
+
+static void *run_vcpu(void *arg)
+{
+       struct payload *payload = (struct payload *)arg;
+       struct kvm_run *state = vcpu_state(payload->vm, payload->index);
+
+       vcpu_run(payload->vm, payload->index);
+
+       TEST_ASSERT(false, "%s: exited with reason %d: %s\n",
+                   __func__, state->exit_reason,
+                   exit_reason_str(state->exit_reason));
+       pthread_exit(NULL);
+}
+
+static void *sleeping_thread(void *arg)
+{
+       int fd;
+
+       while (true) {
+               fd = open("/dev/null", O_RDWR);
+               close(fd);
+       }
+       TEST_ASSERT(false, "%s: exited\n", __func__);
+       pthread_exit(NULL);
+}
+
+static inline void check_create_thread(pthread_t *thread, pthread_attr_t *attr,
+                                      void *(*f)(void *), void *arg)
+{
+       int r;
+
+       r = pthread_create(thread, attr, f, arg);
+       TEST_ASSERT(r == 0, "%s: failed to create thread", __func__);
+}
+
+static inline void check_set_affinity(pthread_t thread, cpu_set_t *cpu_set)
+{
+       int r;
+
+       r = pthread_setaffinity_np(thread, sizeof(cpu_set_t), cpu_set);
+       TEST_ASSERT(r == 0, "%s: failed set affinity", __func__);
+}
+
+static inline void check_join(pthread_t thread, void **retval)
+{
+       int r;
+
+       r = pthread_join(thread, retval);
+       TEST_ASSERT(r == 0, "%s: failed to join thread", __func__);
+}
+
+static void run_test(uint32_t run)
+{
+       struct kvm_vm *vm;
+       cpu_set_t cpu_set;
+       pthread_t threads[VCPU_NUM];
+       pthread_t throw_away;
+       struct payload payloads[VCPU_NUM];
+       void *b;
+       uint32_t i, j;
+
+       CPU_ZERO(&cpu_set);
+       for (i = 0; i < VCPU_NUM; i++)
+               CPU_SET(i, &cpu_set);
+
+       vm = vm_create(VM_MODE_DEFAULT, DEFAULT_GUEST_PHY_PAGES, O_RDWR);
+       kvm_vm_elf_load(vm, program_invocation_name, 0, 0);
+       vm_create_irqchip(vm);
+
+       fprintf(stderr, "%s: [%d] start vcpus\n", __func__, run);
+       for (i = 0; i < VCPU_NUM; ++i) {
+               vm_vcpu_add_default(vm, i, guest_code);
+               payloads[i].vm = vm;
+               payloads[i].index = i;
+
+               check_create_thread(&threads[i], NULL, run_vcpu,
+                                   (void *)&payloads[i]);
+               check_set_affinity(threads[i], &cpu_set);
+
+               for (j = 0; j < SLEEPING_THREAD_NUM; ++j) {
+                       check_create_thread(&throw_away, NULL, sleeping_thread,
+                                           (void *)NULL);
+                       check_set_affinity(throw_away, &cpu_set);
+               }
+       }
+       fprintf(stderr, "%s: [%d] all threads launched\n", __func__, run);
+       sem_post(sem);
+       for (i = 0; i < VCPU_NUM; ++i)
+               check_join(threads[i], &b);
+       /* Should not be reached */
+       TEST_ASSERT(false, "%s: [%d] child escaped the ninja\n", __func__, run);
+}
+
+int main(int argc, char **argv)
+{
+       uint32_t i;
+       int s, r;
+       pid_t pid;
+
+       sem = sem_open("vm_sem", O_CREAT | O_EXCL, 0644, 0);
+       sem_unlink("vm_sem");
+
+       for (i = 0; i < FORK_NUM; ++i) {
+               pid = fork();
+               TEST_ASSERT(pid >= 0, "%s: unable to fork", __func__);
+               if (pid == 0)
+                       run_test(i); /* This function always exits */
+
+               fprintf(stderr, "%s: [%d] waiting semaphore\n", __func__, i);
+               sem_wait(sem);
+               r = (rand() % DELAY_US_MAX) + 1;
+               fprintf(stderr, "%s: [%d] waiting %dus\n", __func__, i, r);
+               usleep(r);
+               r = waitpid(pid, &s, WNOHANG);
+               TEST_ASSERT(r != pid,
+                           "%s: [%d] child exited unexpectedly status: [%d]",
+                           __func__, i, s);
+               fprintf(stderr, "%s: [%d] killing child\n", __func__, i);
+               kill(pid, SIGKILL);
+       }
+
+       sem_destroy(sem);
+       exit(0);
+}


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