[lib][hypervisor] Traps outside of mapped memory

Allow traps to be set that are outside of mapped memory. This will
return success if attempt to set a trap that straddles mappings, but the
trap will not operate correctly in that situation.

Test: Ran "k ut hypervisor".
Change-Id: I0c8a70b9d9564b5892eb96b71c9798d86de9deb6

kernel/lib/hypervisor/guest_physical_address_space.cpp

@@ -114,7 +114,11 @@ zx_status_t GuestPhysicalAddressSpace::MapInterruptController(zx_gpaddr_t guest_
 }
 
 zx_status_t GuestPhysicalAddressSpace::UnmapRange(zx_gpaddr_t guest_paddr, size_t len) {
-    return RootVmar()->Unmap(guest_paddr, len);
+    zx_status_t status = RootVmar()->Unmap(guest_paddr, len);
+    if (status == ZX_ERR_INVALID_ARGS) {
+        return ZX_OK;
+    }
+    return status;
 }
 
 zx_status_t GuestPhysicalAddressSpace::GetPage(zx_gpaddr_t guest_paddr, zx_paddr_t* host_paddr) {

kernel/lib/hypervisor/hypervisor_unittest.cpp

@@ -95,6 +95,28 @@ static bool guest_physical_address_space_unmap_range() {
     END_TEST;
 }
 
+static bool guest_physical_address_space_unmap_range_outside_of_mapping() {
+    BEGIN_TEST;
+
+    if (!hypervisor_supported()) {
+        return true;
+    }
+
+    // Setup.
+    fbl::RefPtr<VmObject> vmo;
+    zx_status_t status = create_vmo(PAGE_SIZE, &vmo);
+    EXPECT_EQ(ZX_OK, status, "Failed to setup VMO.\n");
+    fbl::unique_ptr<hypervisor::GuestPhysicalAddressSpace> gpas;
+    status = create_gpas(vmo, &gpas);
+    EXPECT_EQ(ZX_OK, status, "Failed to create GuestPhysicalAddressSpace.\n");
+
+    // Unmap page.
+    status = gpas->UnmapRange(PAGE_SIZE * 8, PAGE_SIZE);
+    EXPECT_EQ(ZX_OK, status, "Failed to unmap page from GuestPhysicalAddressSpace.\n");
+
+    END_TEST;
+}
+
 static bool guest_physical_address_space_get_page_not_present() {
     BEGIN_TEST;
 
@@ -339,6 +361,7 @@ static bool guest_physical_address_space_write_combining() {
 
 UNITTEST_START_TESTCASE(hypervisor)
 HYPERVISOR_UNITTEST(guest_physical_address_space_unmap_range)
+HYPERVISOR_UNITTEST(guest_physical_address_space_unmap_range_outside_of_mapping)
 HYPERVISOR_UNITTEST(guest_physical_address_space_get_page)
 HYPERVISOR_UNITTEST(guest_physical_address_space_get_page_complex)
 HYPERVISOR_UNITTEST(guest_physical_address_space_get_page_not_present)