[PATCH 06/20] KVM: selftests: Read per-page value into local var when verifying dirty_log_test

Sean Christopherson
2024-12-14T01:07:35Z

Cache the page's value during verification in a local variable, re-reading
from the pointer is ugly and error prone, e.g. allows for bugs like
checking the pointer itself instead of the value.

Signed-off-by: Sean Christopherson <seanjc@google.com>
---
tools/testing/selftests/kvm/dirty_log_test.c | 16 +++++++---------
1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index 08cbecd1a135..5a04a7bd73e0 100644
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -520,11 +520,10 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long *bmap)
{
uint64_t page, nr_dirty_pages = 0, nr_clean_pages = 0;
uint64_t step = vm_num_host_pages(mode, 1);
- uint64_t *value_ptr;
uint64_t min_iter = 0;

for (page = 0; page < host_num_pages; page += step) {
- value_ptr = host_test_mem + page * host_page_size;
+ uint64_t val = *(uint64_t *)(host_test_mem + page * host_page_size);

/* If this is a special page that we were tracking... */
if (__test_and_clear_bit_le(page, host_bmap_track)) {
@@ -545,11 +544,10 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long *bmap)
* the corresponding page should be either the
* previous iteration number or the current one.
*/
- matched = (*value_ptr == iteration ||
- *value_ptr == iteration - 1);
+ matched = (val == iteration || val == iteration - 1);

if (host_log_mode == LOG_MODE_DIRTY_RING && !matched) {
- if (*value_ptr == iteration - 2 && min_iter <= iteration - 2) {
+ if (val == iteration - 2 && min_iter <= iteration - 2) {
/*
* Short answer: this case is special
* only for dirty ring test where the
@@ -597,7 +595,7 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long *bmap)
TEST_ASSERT(matched,
"Set page %"PRIu64" value %"PRIu64
" incorrect (iteration=%"PRIu64")",
- page, *value_ptr, iteration);
+ page, val, iteration);
} else {
nr_clean_pages++;
/*
@@ -619,11 +617,11 @@ static void vm_dirty_log_verify(enum vm_guest_mode mode, unsigned long *bmap)
* we'll see that page P is cleared, with
* value "iteration-1".
*/
- TEST_ASSERT(*value_ptr <= iteration,
+ TEST_ASSERT(val <= iteration,
"Clear page %"PRIu64" value %"PRIu64
" incorrect (iteration=%"PRIu64")",
- page, *value_ptr, iteration);
- if (*value_ptr == iteration) {
+ page, val, iteration);
+ if (val == iteration) {
/*
* This page is _just_ modified; it
* should report its dirtyness in the
--
2.47.1.613.gc27f4b7a9f-goog