[RFC PATCH 34/39] KVM: selftests: Add notes in private_mem_kvm_exits_test for mmap-able guest_memfd

[Ackerley Tng]

Note in comments why madvise() is not needed before setting memory to
private.

Signed-off-by: Ackerley Tng <ackerley...@google.com>
---
 .../selftests/kvm/x86_64/private_mem_kvm_exits_test.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c 
b/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c
index 13e72fcec8dd..f8bcfc897f6a 100644
--- a/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c
+++ b/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c
@@ -62,7 +62,11 @@ static void test_private_access_memslot_deleted(void)
 
        virt_map(vm, EXITS_TEST_GVA, EXITS_TEST_GPA, EXITS_TEST_NPAGES);
 
-       /* Request to access page privately */
+       /*
+        * Request to access page privately. madvise(MADV_DONTNEED) not required
+        * since memory was never mmap()-ed from guest_memfd. Anonymous memory
+        * was used instead for this memslot's userspace_addr.
+        */
        vm_mem_set_private(vm, EXITS_TEST_GPA, EXITS_TEST_SIZE);
 
        pthread_create(&vm_thread, NULL,
@@ -98,7 +102,10 @@ static void test_private_access_memslot_not_private(void)
 
        virt_map(vm, EXITS_TEST_GVA, EXITS_TEST_GPA, EXITS_TEST_NPAGES);
 
-       /* Request to access page privately */
+       /*
+        * Request to access page privately. madvise(MADV_DONTNEED) not required
+        * since the affected memslot doesn't use guest_memfd.
+        */
        vm_mem_set_private(vm, EXITS_TEST_GPA, EXITS_TEST_SIZE);
 
        exit_reason = run_vcpu_get_exit_reason(vcpu);
-- 
2.46.0.598.g6f2099f65c-goog