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, 119 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/state_test.c b/tools/testing/selftests/kvm/state_test.c
new file mode 100644
index 000000000000..e47b27b5406e
--- /dev/null
+++ b/tools/testing/selftests/kvm/state_test.c
@@ -0,0 +1,119 @@
+/*
+ * KVM_GET/SET_* tests
+ *
+ * Copyright (C) 2018, Red Hat, Inc.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ *
+ * Tests for vCPU state save/restore, including nested guest state.
+ */
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include "test_util.h"
+
+#include "kvm_util.h"
+#include "x86.h"
+
+#define VCPU_ID		5
+#define PORT_SYNC	0x1000
+#define PORT_ABORT	0x1001
+#define PORT_DONE	0x1002
+
+static inline void __exit_to_l0(uint16_t port, uint64_t arg0, uint64_t arg1)
+{
+	__asm__ __volatile__("in %[port], %%al"
+			     :
+			     : [port]"d"(port), "D"(arg0), "S"(arg1)
+			     : "rax");
+}
+
+#define exit_to_l0(_port, _arg0, _arg1) \
+	__exit_to_l0(_port, (uint64_t) (_arg0), (uint64_t) (_arg1))
+
+#define GUEST_ASSERT(_condition) do { \
+	if (!(_condition)) \
+		exit_to_l0(PORT_ABORT, "Failed guest assert: " #_condition, __LINE__);\
+} while (0)
+
+#define GUEST_SYNC(stage) \
+	exit_to_l0(PORT_SYNC, "hello", stage);
+
+static bool have_nested_state;
+
+void guest_code(void)
+{
+	GUEST_SYNC(1);
+	GUEST_SYNC(2);
+
+	exit_to_l0(PORT_DONE, 0, 0);
+}
+
+int main(int argc, char *argv[])
+{
+	struct kvm_regs regs1, regs2;
+	struct kvm_vm *vm;
+	struct kvm_run *run;
+	struct kvm_x86_state *state;
+	int stage;
+
+	struct kvm_cpuid_entry2 *entry = kvm_get_supported_cpuid_entry(1);
+
+	/* Create VM */
+	vm = vm_create_default(VCPU_ID, guest_code);
+	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+	run = vcpu_state(vm, VCPU_ID);
+
+	vcpu_regs_get(vm, VCPU_ID, &regs1);
+	for (stage = 1;; stage++) {
+		_vcpu_run(vm, VCPU_ID);
+		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+			    "Unexpected exit reason: %u (%s),\n",
+			    run->exit_reason,
+			    exit_reason_str(run->exit_reason));
+
+		memset(&regs1, 0, sizeof(regs1));
+		vcpu_regs_get(vm, VCPU_ID, &regs1);
+		switch (run->io.port) {
+		case PORT_ABORT:
+			TEST_ASSERT(false, "%s at %s:%d", (const char *) regs1.rdi,
+				    __FILE__, regs1.rsi);
+			/* NOT REACHED */
+		case PORT_SYNC:
+			break;
+		case PORT_DONE:
+			goto done;
+		default:
+			TEST_ASSERT(false, "Unknown port 0x%x.", run->io.port);
+		}
+
+		/* PORT_SYNC is handled here.  */
+		TEST_ASSERT(!strcmp((const char *)regs1.rdi, "hello") &&
+			    regs1.rsi == stage, "Unexpected register values vmexit #%lx, got %lx",
+			    stage, (ulong) regs1.rsi);
+
+		state = vcpu_save_state(vm, VCPU_ID);
+		kvm_vm_release(vm);
+
+		/* Restore state in a new VM.  */
+		kvm_vm_restart(vm, O_RDWR);
+		vm_vcpu_add(vm, VCPU_ID, 0, 0);
+		vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+		vcpu_load_state(vm, VCPU_ID, state);
+		run = vcpu_state(vm, VCPU_ID);
+		free(state);
+
+		memset(&regs2, 0, sizeof(regs2));
+		vcpu_regs_get(vm, VCPU_ID, &regs2);
+		TEST_ASSERT(!memcmp(&regs1, &regs2, sizeof(regs2)),
+			    "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx",
+			    (ulong) regs2.rdi, (ulong) regs2.rsi);
+	}
+
+done:
+	kvm_vm_free(vm);
+}