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Date: Mon, 15 Feb 2021 17:43:55 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: Marc Orr <marcorr@...gle.com>, ikalvarado@...gle.com,
huah@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
linux-kselftest@...r.kernel.org, brijesh.singh@....com,
Thomas.Lendacky@....com, jmattson@...gle.com
Subject: Re: [PATCH] selftests: kvm: add hardware_disable test
On 13/02/21 01:14, Marc Orr wrote:
> From: Ignacio Alvarado <ikalvarado@...gle.com>
>
> 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_PTGp3g@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 <ikalvarado@...gle.com>
> Signed-off-by: Marc Orr <marcorr@...gle.com>
> ---
> 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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