diff options
| -rw-r--r-- | tools/testing/selftests/kvm/dirty_log_test.c | 40 |
1 files changed, 36 insertions, 4 deletions
diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c index 500257b712e3..c6b843ec8e0c 100644 --- a/tools/testing/selftests/kvm/dirty_log_test.c +++ b/tools/testing/selftests/kvm/dirty_log_test.c @@ -37,6 +37,12 @@ /* Interval for each host loop (ms) */ #define TEST_HOST_LOOP_INTERVAL 10UL +/* + * Ensure the vCPU is able to perform a reasonable number of writes in each + * iteration to provide a lower bound on coverage. + */ +#define TEST_MIN_WRITES_PER_ITERATION 0x100 + /* Dirty bitmaps are always little endian, so we need to swap on big endian */ #if defined(__s390x__) # define BITOP_LE_SWIZZLE ((BITS_PER_LONG-1) & ~0x7) @@ -72,6 +78,7 @@ static uint64_t host_page_size; static uint64_t guest_page_size; static uint64_t guest_num_pages; static uint64_t iteration; +static uint64_t nr_writes; static bool vcpu_stop; /* @@ -107,6 +114,7 @@ static void guest_code(void) for (i = 0; i < guest_num_pages; i++) { addr = guest_test_virt_mem + i * guest_page_size; vcpu_arch_put_guest(*(uint64_t *)addr, READ_ONCE(iteration)); + nr_writes++; } #endif @@ -118,6 +126,7 @@ static void guest_code(void) addr = align_down(addr, host_page_size); vcpu_arch_put_guest(*(uint64_t *)addr, READ_ONCE(iteration)); + nr_writes++; } GUEST_SYNC(1); @@ -548,8 +557,8 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long **bmap) } } - pr_info("Iteration %2ld: dirty: %-6lu clean: %-6lu\n", - iteration, nr_dirty_pages, nr_clean_pages); + pr_info("Iteration %2ld: dirty: %-6lu clean: %-6lu writes: %-6lu\n", + iteration, nr_dirty_pages, nr_clean_pages, nr_writes); host_dirty_count += nr_dirty_pages; host_clear_count += nr_clean_pages; @@ -665,6 +674,8 @@ static void run_test(enum vm_guest_mode mode, void *arg) host_dirty_count = 0; host_clear_count = 0; WRITE_ONCE(dirty_ring_vcpu_ring_full, false); + WRITE_ONCE(nr_writes, 0); + sync_global_to_guest(vm, nr_writes); /* * Ensure the previous iteration didn't leave a dangling semaphore, i.e. @@ -683,10 +694,22 @@ static void run_test(enum vm_guest_mode mode, void *arg) dirty_ring_prev_iteration_last_page = dirty_ring_last_page; - /* Give the vcpu thread some time to dirty some pages */ - for (i = 0; i < p->interval; i++) { + /* + * Let the vCPU run beyond the configured interval until it has + * performed the minimum number of writes. This verifies the + * guest is making forward progress, e.g. isn't stuck because + * of a KVM bug, and puts a firm floor on test coverage. + */ + for (i = 0; i < p->interval || nr_writes < TEST_MIN_WRITES_PER_ITERATION; i++) { + /* + * Sleep in 1ms chunks to keep the interval math simple + * and so that the test doesn't run too far beyond the + * specified interval. + */ usleep(1000); + sync_global_from_guest(vm, nr_writes); + /* * Reap dirty pages while the guest is running so that * dirty ring full events are resolved, i.e. so that a @@ -738,6 +761,12 @@ static void run_test(enum vm_guest_mode mode, void *arg) sync_global_to_guest(vm, vcpu_stop); /* + * Sync the number of writes performed before verification, the + * info will be printed along with the dirty/clean page counts. + */ + sync_global_from_guest(vm, nr_writes); + + /* * NOTE: for dirty ring, it's possible that we didn't stop at * GUEST_SYNC but instead we stopped because ring is full; * that's okay too because ring full means we're only missing @@ -760,6 +789,9 @@ static void run_test(enum vm_guest_mode mode, void *arg) WRITE_ONCE(host_quit, true); sync_global_to_guest(vm, iteration); + WRITE_ONCE(nr_writes, 0); + sync_global_to_guest(vm, nr_writes); + WRITE_ONCE(dirty_ring_vcpu_ring_full, false); sem_post(&sem_vcpu_cont); |