kvm: selftests: add basic test for state save and restore

The test calls KVM_RUN repeatedly, and creates an entirely new VM with the
old memory and vCPU state on every exit to userspace.  The kvm_util API is
expanded with two functions that manage the lifetime of a kvm_vm struct:
the first closes the file descriptors and leaves the memory allocated,
and the second opens the file descriptors and reuses the memory from
the previous incarnation of the kvm_vm struct.

For now the test is very basic, as it does not test for example XSAVE or
vCPU events.  However, it will test nested virtualization state starting
with the next patch.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 66 insertions, 22 deletions

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 163482873363..643309d6de74 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -62,6 +62,18 @@ int kvm_check_cap(long cap)
 	return ret;
 }
 
+static void vm_open(struct kvm_vm *vm, int perm)
+{
+	vm->kvm_fd = open(KVM_DEV_PATH, perm);
+	if (vm->kvm_fd < 0)
+		exit(KSFT_SKIP);
+
+	/* Create VM. */
+	vm->fd = ioctl(vm->kvm_fd, KVM_CREATE_VM, NULL);
+	TEST_ASSERT(vm->fd >= 0, "KVM_CREATE_VM ioctl failed, "
+		"rc: %i errno: %i", vm->fd, errno);
+}
+
 /* VM Create
  *
  * Input Args:
@@ -90,16 +102,7 @@ struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
 	TEST_ASSERT(vm != NULL, "Insufficent Memory");
 
 	vm->mode = mode;
-	kvm_fd = open(KVM_DEV_PATH, perm);
-	if (kvm_fd < 0)
-		exit(KSFT_SKIP);
-
-	/* Create VM. */
-	vm->fd = ioctl(kvm_fd, KVM_CREATE_VM, NULL);
-	TEST_ASSERT(vm->fd >= 0, "KVM_CREATE_VM ioctl failed, "
-		"rc: %i errno: %i", vm->fd, errno);
-
-	close(kvm_fd);
+	vm_open(vm, perm);
 
 	/* Setup mode specific traits. */
 	switch (vm->mode) {
@@ -132,6 +135,39 @@ struct kvm_vm *vm_create(enum vm_guest_mode mode, uint64_t phy_pages, int perm)
 	return vm;
 }
 
+/* VM Restart
+ *
+ * Input Args:
+ *   vm - VM that has been released before
+ *   perm - permission
+ *
+ * Output Args: None
+ *
+ * Reopens the file descriptors associated to the VM and reinstates the
+ * global state, such as the irqchip and the memory regions that are mapped
+ * into the guest.
+ */
+void kvm_vm_restart(struct kvm_vm *vmp, int perm)
+{
+	struct userspace_mem_region *region;
+
+	vm_open(vmp, perm);
+	if (vmp->has_irqchip)
+		vm_create_irqchip(vmp);
+
+	for (region = vmp->userspace_mem_region_head; region;
+		region = region->next) {
+		int ret = ioctl(vmp->fd, KVM_SET_USER_MEMORY_REGION, &region->region);
+		TEST_ASSERT(ret == 0, "KVM_SET_USER_MEMORY_REGION IOCTL failed,\n"
+			    "  rc: %i errno: %i\n"
+			    "  slot: %u flags: 0x%x\n"
+			    "  guest_phys_addr: 0x%lx size: 0x%lx",
+			    ret, errno, region->region.slot, region->region.flags,
+			    region->region.guest_phys_addr,
+			    region->region.memory_size);
+	}
+}
+
 /* Userspace Memory Region Find
  *
  * Input Args:
@@ -256,6 +292,23 @@ static void vm_vcpu_rm(struct kvm_vm *vm, uint32_t vcpuid)
 	free(vcpu);
 }
 
+void kvm_vm_release(struct kvm_vm *vmp)
+{
+	int ret;
+
+	/* Free VCPUs. */
+	while (vmp->vcpu_head)
+		vm_vcpu_rm(vmp, vmp->vcpu_head->id);
+
+	/* Close file descriptor for the VM. */
+	ret = close(vmp->fd);
+	TEST_ASSERT(ret == 0, "Close of vm fd failed,\n"
+		"  vmp->fd: %i rc: %i errno: %i", vmp->fd, ret, errno);
+
+	close(vmp->kvm_fd);
+	TEST_ASSERT(ret == 0, "Close of /dev/kvm fd failed,\n"
+		"  vmp->kvm_fd: %i rc: %i errno: %i", vmp->kvm_fd, ret, errno);
+}
 
 /* Destroys and frees the VM pointed to by vmp.
  */
@@ -286,22 +339,11 @@ void kvm_vm_free(struct kvm_vm *vmp)
 		free(region);
 	}
 
-	/* Free VCPUs. */
-	while (vmp->vcpu_head)
-		vm_vcpu_rm(vmp, vmp->vcpu_head->id);
-
 	/* Free sparsebit arrays. */
 	sparsebit_free(&vmp->vpages_valid);
 	sparsebit_free(&vmp->vpages_mapped);
 
-	/* Close file descriptor for the VM. */
-	ret = close(vmp->fd);
-	TEST_ASSERT(ret == 0, "Close of vm fd failed,\n"
-		"  vmp->fd: %i rc: %i errno: %i", vmp->fd, ret, errno);
-
-	close(vmp->kvm_fd);
-	TEST_ASSERT(ret == 0, "Close of /dev/kvm fd failed,\n"
-		"  vmp->kvm_fd: %i rc: %i errno: %i", vmp->kvm_fd, ret, errno);
+	kvm_vm_release(vmp);
 
 	/* Free the structure describing the VM. */
 	free(vmp);
@@ -965,6 +1007,8 @@ void vm_create_irqchip(struct kvm_vm *vm)
 	ret = ioctl(vm->fd, KVM_CREATE_IRQCHIP, 0);
 	TEST_ASSERT(ret == 0, "KVM_CREATE_IRQCHIP IOCTL failed, "
 		"rc: %i errno: %i", ret, errno);
+
+	vm->has_irqchip = true;
 }
 
 /* VM VCPU State