kvm: selftests: dirty_log_test: don't identity map the test mem

It isn't necessary and can even cause problems when testing high
guest physical addresses. This patch leaves the test memory id-
mapped by default, but when using '-t' the test memory virtual
addresses stay the same even though the physical addresses switch
to the topmost valid addresses.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index 3be1539..f68eee9 100644 (file)
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -52,9 +52,10 @@ static uint64_t iteration;
 
 /*
  * GPA offset of the testing memory slot. Must be bigger than
- * DEFAULT_GUEST_PHY_PAGES.
+ * DEFAULT_GUEST_PHY_PAGES * PAGE_SIZE.
  */
-static uint64_t guest_test_mem = DEFAULT_GUEST_TEST_MEM;
+static uint64_t guest_test_phys_mem = DEFAULT_GUEST_TEST_MEM;
+static uint64_t guest_test_virt_mem = DEFAULT_GUEST_TEST_MEM;
 
 /*
  * Continuously write to the first 8 bytes of a random pages within
@@ -66,7 +67,7 @@ static void guest_code(void)
 
        while (true) {
                for (i = 0; i < TEST_PAGES_PER_LOOP; i++) {
-                       uint64_t addr = guest_test_mem;
+                       uint64_t addr = guest_test_virt_mem;
                        addr += (READ_ONCE(random_array[i]) % guest_num_pages)
                                * guest_page_size;
                        addr &= ~(host_page_size - 1);
@@ -273,11 +274,11 @@ static void run_test(enum vm_guest_mode mode, unsigned long iterations,
                         !!((guest_num_pages * guest_page_size) % host_page_size);
 
        if (top_offset) {
-               guest_test_mem = (max_gfn - guest_num_pages) * guest_page_size;
-               guest_test_mem &= ~(host_page_size - 1);
+               guest_test_phys_mem = (max_gfn - guest_num_pages) * guest_page_size;
+               guest_test_phys_mem &= ~(host_page_size - 1);
        }
 
-       DEBUG("guest test mem offset: 0x%lx\n", guest_test_mem);
+       DEBUG("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
 
        bmap = bitmap_alloc(host_num_pages);
        host_bmap_track = bitmap_alloc(host_num_pages);
@@ -294,17 +295,17 @@ static void run_test(enum vm_guest_mode mode, unsigned long iterations,
 
        /* Add an extra memory slot for testing dirty logging */
        vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
-                                   guest_test_mem,
+                                   guest_test_phys_mem,
                                    TEST_MEM_SLOT_INDEX,
                                    guest_num_pages,
                                    KVM_MEM_LOG_DIRTY_PAGES);
 
-       /* Do 1:1 mapping for the dirty track memory slot */
-       virt_map(vm, guest_test_mem, guest_test_mem,
+       /* Do mapping for the dirty track memory slot */
+       virt_map(vm, guest_test_virt_mem, guest_test_phys_mem,
                 guest_num_pages * guest_page_size, 0);
 
        /* Cache the HVA pointer of the region */
-       host_test_mem = addr_gpa2hva(vm, (vm_paddr_t)guest_test_mem);
+       host_test_mem = addr_gpa2hva(vm, (vm_paddr_t)guest_test_phys_mem);
 
 #ifdef __x86_64__
        vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
@@ -316,7 +317,7 @@ static void run_test(enum vm_guest_mode mode, unsigned long iterations,
        /* Export the shared variables to the guest */
        sync_global_to_guest(vm, host_page_size);
        sync_global_to_guest(vm, guest_page_size);
-       sync_global_to_guest(vm, guest_test_mem);
+       sync_global_to_guest(vm, guest_test_virt_mem);
        sync_global_to_guest(vm, guest_num_pages);
 
        /* Start the iterations */
@@ -429,7 +430,7 @@ int main(int argc, char *argv[])
                        interval = strtol(optarg, NULL, 10);
                        break;
                case 'o':
-                       guest_test_mem = strtoull(optarg, NULL, 0);
+                       guest_test_phys_mem = strtoull(optarg, NULL, 0);
                        break;
                case 't':
                        top_offset = true;
@@ -454,7 +455,7 @@ int main(int argc, char *argv[])
 
        TEST_ASSERT(iterations > 2, "Iterations must be greater than two");
        TEST_ASSERT(interval > 0, "Interval must be greater than zero");
-       TEST_ASSERT(!top_offset || guest_test_mem == DEFAULT_GUEST_TEST_MEM,
+       TEST_ASSERT(!top_offset || guest_test_phys_mem == DEFAULT_GUEST_TEST_MEM,
                    "Cannot use both -o [offset] and -t at the same time");
 
        DEBUG("Test iterations: %"PRIu64", interval: %"PRIu64" (ms)\n",