Re: [PATCH v4 21/21] KVM: selftests: Test READ=>WRITE dirty logging behavior for shadow MMU

@@ -106,12 +139,66 @@ static void l1_guest_code(void *data)
 		l1_svm_code(data);
 }
 
+static void test_handle_ucall_sync(struct kvm_vm *vm, u64 arg,
+				   unsigned long *bmap)
+{
+	vm_vaddr_t gva = arg & ~(PAGE_SIZE - 1);
+	int page_nr, i;
+
+	/*
+	 * Extract the page number of underlying physical page, which is also
+	 * the _L1_ page number.  The dirty bitmap _must_ be updated based on
+	 * the L1 GPA, not L2 GPA, i.e. whether or not L2 used an aliased GPA
+	 * (i.e. if TDP enabled for L2) is irrelevant with respect to the dirty
+	 * bitmap and which underlying physical page is accessed.
+	 *
+	 * Note, gva will be '0' if there was no access, i.e. if the purpose of
+	 * the sync is to verify all pages are clean.
+	 */
+	if (!gva)
+		page_nr = 0;
+	else if (gva >= TEST_MEM_ALIAS_BASE)
+		page_nr = (gva - TEST_MEM_ALIAS_BASE) >> PAGE_SHIFT;
+	else
+		page_nr = (gva - TEST_MEM_BASE) >> PAGE_SHIFT;
+	TEST_ASSERT(page_nr == 0 || page_nr == 1,
+		    "Test bug, unexpected frame number '%u' for arg = %lx", page_nr, arg);
+	TEST_ASSERT(gva || (arg & TEST_SYNC_NO_FAULT),
+		    "Test bug, gva must be valid if a fault is expected");
+
+	kvm_vm_get_dirty_log(vm, TEST_MEM_SLOT_INDEX, bmap);
+
+	/*
+	 * Check all pages to verify the correct physical page was modified (or
+	 * not), and that all pages are clean/dirty as expected.
+	 *
+	 * If a fault of any kind is expected, the target page should be dirty
+	 * as the Dirty bit is set in the gPTE.  KVM should create a writable
+	 * SPTE even on a read fault, *and* KVM must mark the GFN as dirty
+	 * when doing so.
+	 */
+	for (i = 0; i < TEST_MEM_PAGES; i++) {
+		if (i == page_nr && arg & TEST_SYNC_WRITE_FAULT)