Re: [RFC PATCH v2 3/3] KVM: selftests: Add set_memory_region_io to test memslots for MMIO BARs

On Wed, Jan 03, 2024 at 04:45:35PM +0800, Yan Zhao wrote:

Added a selftest set_memory_region_io to test memslots for MMIO BARs.

Emm.. "set_memory_region_io" doesn't represent the real testing purpose, but not sure if things like "memory_region_page_refcount_test" become better...

The MMIO BARs' backends are compound/non-compound huge pages serving as device resources allocated by a mock device driver.

This selftest will assert and report "errno=14 - Bad address" in vcpu_run() if any failure is met to add such MMIO BAR memslots. After MMIO memslots removal, page reference counts of the device resources are also checked.

As this selftest will interacts with a mock device "/dev/kvm_mock_device", it depends on test driver test_kvm_mock_device.ko in the kernel. CONFIG_TEST_KVM_MOCK_DEVICE=m must be enabled in the kernel.

Currently, this selftest is only compiled for __x86_64__.

Signed-off-by: Yan Zhao yan.y.zhao@intel.com

tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/set_memory_region_io.c | 188 ++++++++++++++++++ 2 files changed, 189 insertions(+) create mode 100644 tools/testing/selftests/kvm/set_memory_region_io.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 4412b42d95de..9d39514b6403 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -144,6 +144,7 @@ TEST_GEN_PROGS_x86_64 += memslot_modification_stress_test TEST_GEN_PROGS_x86_64 += memslot_perf_test TEST_GEN_PROGS_x86_64 += rseq_test TEST_GEN_PROGS_x86_64 += set_memory_region_test +TEST_GEN_PROGS_x86_64 += set_memory_region_io 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 diff --git a/tools/testing/selftests/kvm/set_memory_region_io.c b/tools/testing/selftests/kvm/set_memory_region_io.c new file mode 100644 index 000000000000..e221103091f4 --- /dev/null +++ b/tools/testing/selftests/kvm/set_memory_region_io.c @@ -0,0 +1,188 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE /* for program_invocation_short_name */ +#include <fcntl.h> +#include <pthread.h> +#include <sched.h> +#include <semaphore.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/ioctl.h> +#include <sys/mman.h>

+#include <linux/compiler.h>

+#include <test_util.h> +#include <kvm_util.h> +#include <processor.h>

+#include <../../../../lib/test_kvm_mock_device_uapi.h>

+/*

• • Somewhat arbitrary location and slot, intended to not overlap anything.
• */

+#define MEM_REGION_GPA_BASE 0xc0000000 +#define RANDOM_OFFSET 0x1000 +#define MEM_REGION_GPA_RANDOM (MEM_REGION_GPA_BASE + RANDOM_OFFSET) +#define MEM_REGION_SLOT_ID 10

+static const bool non_compound_supported;

+static const uint64_t BASE_VAL = 0x1111; +static const uint64_t RANDOM_VAL = 0x2222;

+static unsigned long bar_size;

+static sem_t vcpu_ready;

+static void guest_code_read_bar(void) +{

• uint64_t val;
• GUEST_SYNC(0);
• val = READ_ONCE(*((uint64_t *)MEM_REGION_GPA_RANDOM));
• GUEST_ASSERT_EQ(val, RANDOM_VAL);
• val = READ_ONCE(*((uint64_t *)MEM_REGION_GPA_BASE));
• GUEST_ASSERT_EQ(val, BASE_VAL);
• GUEST_DONE();

+}

+static void *vcpu_worker(void *data) +{

• struct kvm_vcpu *vcpu = data;
• struct kvm_run *run = vcpu->run;
• struct ucall uc;
• uint64_t cmd;
• /*

• * Loop until the guest is done.  Re-enter the guest on all MMIO exits,
  

• * which will occur if the guest attempts to access a memslot after it
  

• * has been deleted or while it is being moved .
  

• */
  

• while (1) {

• vcpu_run(vcpu);
  

• if (run->exit_reason == KVM_EXIT_IO) {
  

• 	cmd = get_ucall(vcpu, &uc);
  

• 	if (cmd != UCALL_SYNC)
  

• 		break;
  

• 	sem_post(&vcpu_ready);
  

• 	continue;
  

• }
  

• if (run->exit_reason != KVM_EXIT_MMIO)
  

• 	break;
  

Can the KVM_EXIT_MMIO happen on x86 ? IIUC the accessed GVAs in guest code have 1:1 mapping to MEM_REGION_GPA_BASE, which is covered by the memslot, and the memory slot is there until the guest code path done.

• TEST_ASSERT(!run->mmio.is_write, "Unexpected exit mmio write");
  

• TEST_ASSERT(run->mmio.len == 8,
  

• 	    "Unexpected exit mmio size = %u", run->mmio.len);
  

• TEST_ASSERT(run->mmio.phys_addr < MEM_REGION_GPA_BASE ||
  

• 	    run->mmio.phys_addr >= MEM_REGION_GPA_BASE + bar_size,
  

• 	    "Unexpected exit mmio address = 0x%llx",
  

• 	    run->mmio.phys_addr);
  

Ditto, I just think you don't need this part in this testing.

• }
• if (run->exit_reason == KVM_EXIT_IO && cmd == UCALL_ABORT)

• REPORT_GUEST_ASSERT(uc);
  

• return NULL;

+}

+static void wait_for_vcpu(void) +{

• struct timespec ts;
• TEST_ASSERT(!clock_gettime(CLOCK_REALTIME, &ts),

•     "clock_gettime() failed: %d\n", errno);
  

• ts.tv_sec += 2;
• TEST_ASSERT(!sem_timedwait(&vcpu_ready, &ts),

•     "sem_timedwait() failed: %d\n", errno);
  

• /* Wait for the vCPU thread to reenter the guest. */
• usleep(100000);

In this testing it's not needed. Because you only check guest state after guest code path done, so pthread_join() is enough there.

+}

+static void test_kvm_mock_device_bar(bool compound) +{

• struct kvm_vm *vm;
• void *mem;
• struct kvm_vcpu *vcpu;
• pthread_t vcpu_thread;
• int fd, ret;
• u32 param_compound = compound;
• u32 inequal = 0;
• fd = open("/dev/kvm_mock_device", O_RDWR);
• if (fd < 0) {

• pr_info("Please ensure \"CONFIG_TEST_KVM_MOCK_DEVICE=m\" is enabled in the kernel");
  

• pr_info(", and execute\n\"modprobe test_kvm_mock_device\n");
  

• }
• TEST_ASSERT(fd >= 0, "Failed to open kvm mock device.");

Minor: May better to move this part into main(), highlight it's a must have dependency at beginning.

• ret = ioctl(fd, KVM_MOCK_DEVICE_GET_BAR_SIZE, &bar_size);
• TEST_ASSERT(ret == 0, "Failed to get bar size of kvm mock device");
• ret = ioctl(fd, KVM_MOCK_DEVICE_PREPARE_RESOURCE, &param_compound);
• TEST_ASSERT(ret == 0, "Failed to prepare resource of kvm mock device");
• mem = mmap(NULL, (size_t)bar_size, PROT_READ | PROT_WRITE, MAP_SHARED,

•    fd, 0);
  

• TEST_ASSERT(mem != MAP_FAILED, "Failed to mmap() kvm mock device bar");
• *(u64 *)mem = BASE_VAL;
• *(u64 *)(mem + RANDOM_OFFSET) = RANDOM_VAL;
• vm = vm_create_with_one_vcpu(&vcpu, guest_code_read_bar);
• vm_set_user_memory_region(vm, MEM_REGION_SLOT_ID, 0, MEM_REGION_GPA_BASE,

• 		  bar_size, mem);
  

• virt_map(vm, MEM_REGION_GPA_BASE, MEM_REGION_GPA_BASE,

•  (RANDOM_OFFSET / getpagesize()) + 1);
  

• pthread_create(&vcpu_thread, NULL, vcpu_worker, vcpu);
• /* Ensure the guest thread is spun up. */
• wait_for_vcpu();
• pthread_join(vcpu_thread, NULL);
• vm_set_user_memory_region(vm, MEM_REGION_SLOT_ID, 0, 0, 0, 0);
• kvm_vm_free(vm);
• ret = ioctl(fd, KVM_MOCK_DEVICE_CHECK_BACKEND_REF, &inequal);
• TEST_ASSERT(ret == 0 && inequal == 0, "Incorrect resource ref of KVM device");
• munmap(mem, bar_size);
• close(fd);

+}

+static void test_non_compound_backend(void) +{

• pr_info("Testing non-compound huge page backend for mem slot\n");
• test_kvm_mock_device_bar(false);

+}

+static void test_compound_backend(void) +{

• pr_info("Testing compound huge page backend for mem slot\n");
• test_kvm_mock_device_bar(true);

+}

+int main(int argc, char *argv[]) +{ +#ifdef __x86_64__

• test_compound_backend();
• if (non_compound_supported)

Nobody set this, but the mock device looks already supported it, so how about just run the 2 testings directly here ?

• test_non_compound_backend();
  

+#endif

• return 0;

+}

2.17.1