KVM: selftests: aarch64: Fix check of dirty log PT write

The dirty log checks are mistakenly testing the first page in the page
table (PT) memory region instead of the page holding the test data
page PTE.  This wasn't an issue before commit 406504c7 ("KVM:
arm64: Fix S1PTW handling on RO memslots") as all PT pages (including
the first page) were treated as writes.

Fix the page_fault_test dirty logging tests by checking for the right
page: the one for the PTE of the data test page.

Fixes: a4edf25b ("KVM: selftests: aarch64: Add dirty logging tests into page_fault_test")
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230127214353.245671-4-ricarkol@google.com

tools/testing/selftests/kvm/aarch64/page_fault_test.c

@@ -470,9 +470,12 @@ static bool handle_cmd(struct kvm_vm *vm, int cmd)
 {
 	struct userspace_mem_region *data_region, *pt_region;
 	bool continue_test = true;
+	uint64_t pte_gpa, pte_pg;
 
 	data_region = vm_get_mem_region(vm, MEM_REGION_TEST_DATA);
 	pt_region = vm_get_mem_region(vm, MEM_REGION_PT);
+	pte_gpa = addr_hva2gpa(vm, virt_get_pte_hva(vm, TEST_GVA));
+	pte_pg = (pte_gpa - pt_region->region.guest_phys_addr) / getpagesize();
 
 	if (cmd == CMD_SKIP_TEST)
 		continue_test = false;
@@ -485,13 +488,13 @@ static bool handle_cmd(struct kvm_vm *vm, int cmd)
 		TEST_ASSERT(check_write_in_dirty_log(vm, data_region, 0),
 			    "Missing write in dirty log");
 	if (cmd & CMD_CHECK_S1PTW_WR_IN_DIRTY_LOG)
-		TEST_ASSERT(check_write_in_dirty_log(vm, pt_region, 0),
+		TEST_ASSERT(check_write_in_dirty_log(vm, pt_region, pte_pg),
 			    "Missing s1ptw write in dirty log");
 	if (cmd & CMD_CHECK_NO_WRITE_IN_DIRTY_LOG)
 		TEST_ASSERT(!check_write_in_dirty_log(vm, data_region, 0),
 			    "Unexpected write in dirty log");
 	if (cmd & CMD_CHECK_NO_S1PTW_WR_IN_DIRTY_LOG)
-		TEST_ASSERT(!check_write_in_dirty_log(vm, pt_region, 0),
+		TEST_ASSERT(!check_write_in_dirty_log(vm, pt_region, pte_pg),
 			    "Unexpected s1ptw write in dirty log");
 
 	return continue_test;