[PATCH 1/3] selftests: kvm/evmcs_test: complete I/O before migrating guest state

[Paolo Bonzini <pbonzini@redhat.com>]

Starting state migration after an IO exit without first completing IO
may result in test failures.  We already have two tests that need this
(this patch in fact fixes evmcs_test, similar to what was fixed for
state_test in commit 0f73bbc851ed, "KVM: selftests: complete IO before
migrating guest state", 2019-03-13) and a third is coming.  So, move the
code to vcpu_save_state, and while at it do not access register state
until after I/O is complete.
---
 tools/testing/selftests/kvm/lib/kvm_util.c         |  5 +++++
 tools/testing/selftests/kvm/lib/x86_64/processor.c |  8 ++++++++
 tools/testing/selftests/kvm/x86_64/evmcs_test.c    |  5 +++--
 tools/testing/selftests/kvm/x86_64/state_test.c    | 15 +--------------
 4 files changed, 17 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index efa0aad8b3c6..4ca96b228e46 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -91,6 +91,11 @@ static void vm_open(struct kvm_vm *vm, int perm, unsigned long type)
 	if (vm->kvm_fd < 0)
 		exit(KSFT_SKIP);
 
+	if (!kvm_check_cap(KVM_CAP_IMMEDIATE_EXIT)) {
+		fprintf(stderr, "immediate_exit not available, skipping test\n");
+		exit(KSFT_SKIP);
+	}
+
 	vm->fd = ioctl(vm->kvm_fd, KVM_CREATE_VM, type);
 	TEST_ASSERT(vm->fd >= 0, "KVM_CREATE_VM ioctl failed, "
 		"rc: %i errno: %i", vm->fd, errno);
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index f28127f4a3af..b363c9611bd6 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1030,6 +1030,14 @@ struct kvm_x86_state *vcpu_save_state(struct kvm_vm *vm, uint32_t vcpuid)
 			    nested_size, sizeof(state->nested_));
 	}
 
+	/*
+	 * When KVM exits to userspace with KVM_EXIT_IO, KVM guarantees
+	 * guest state is consistent only after userspace re-enters the
+	 * kernel with KVM_RUN.  Complete IO prior to migrating state
+	 * to a new VM.
+	 */
+	vcpu_run_complete_io(vm, vcpuid);
+
 	nmsrs = kvm_get_num_msrs(vm);
 	list = malloc(sizeof(*list) + nmsrs * sizeof(list->indices[0]));
 	list->nmsrs = nmsrs;
diff --git a/tools/testing/selftests/kvm/x86_64/evmcs_test.c b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
index c49c2a28b0eb..36669684eca5 100644
--- a/tools/testing/selftests/kvm/x86_64/evmcs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
@@ -123,8 +123,6 @@ int main(int argc, char *argv[])
 			    stage, run->exit_reason,
 			    exit_reason_str(run->exit_reason));
 
-		memset(&regs1, 0, sizeof(regs1));
-		vcpu_regs_get(vm, VCPU_ID, &regs1);
 		switch (get_ucall(vm, VCPU_ID, &uc)) {
 		case UCALL_ABORT:
 			TEST_ASSERT(false, "%s at %s:%d", (const char *)uc.args[0],
@@ -144,6 +142,9 @@ int main(int argc, char *argv[])
 			    stage, (ulong)uc.args[1]);
 
 		state = vcpu_save_state(vm, VCPU_ID);
+		memset(&regs1, 0, sizeof(regs1));
+		vcpu_regs_get(vm, VCPU_ID, &regs1);
+
 		kvm_vm_release(vm);
 
 		/* Restore state in a new VM.  */
diff --git a/tools/testing/selftests/kvm/x86_64/state_test.c b/tools/testing/selftests/kvm/x86_64/state_test.c
index 30f75856cf39..e0a3c0204b7c 100644
--- a/tools/testing/selftests/kvm/x86_64/state_test.c
+++ b/tools/testing/selftests/kvm/x86_64/state_test.c
@@ -134,11 +134,6 @@ int main(int argc, char *argv[])
 
 	struct kvm_cpuid_entry2 *entry = kvm_get_supported_cpuid_entry(1);
 
-	if (!kvm_check_cap(KVM_CAP_IMMEDIATE_EXIT)) {
-		fprintf(stderr, "immediate_exit not available, skipping test\n");
-		exit(KSFT_SKIP);
-	}
-
 	/* Create VM */
 	vm = vm_create_default(VCPU_ID, 0, guest_code);
 	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
@@ -179,18 +174,10 @@ int main(int argc, char *argv[])
 			    uc.args[1] == stage, "Unexpected register values vmexit #%lx, got %lx",
 			    stage, (ulong)uc.args[1]);
 
-		/*
-		 * When KVM exits to userspace with KVM_EXIT_IO, KVM guarantees
-		 * guest state is consistent only after userspace re-enters the
-		 * kernel with KVM_RUN.  Complete IO prior to migrating state
-		 * to a new VM.
-		 */
-		vcpu_run_complete_io(vm, VCPU_ID);
-
+		state = vcpu_save_state(vm, VCPU_ID);
 		memset(&regs1, 0, sizeof(regs1));
 		vcpu_regs_get(vm, VCPU_ID, &regs1);
 
-		state = vcpu_save_state(vm, VCPU_ID);
 		kvm_vm_release(vm);
 
 		/* Restore state in a new VM.  */
-- 
1.8.3.1