tests: kvm: Check for a kernel warning

When running with /sys/module/kvm_intel/parameters/unrestricted_guest=N,
test that a kernel warning does not occur informing us that
vcpu->mmio_needed=1.  This can happen when KVM_RUN is called after a
triple fault.
This test was made to detect a bug that was reported by Syzkaller
(https://groups.google.com/forum/#!topic/syzkaller/lHfau8E3SOE) and
fixed with commit bbeac2830f4de ("KVM: X86: Fix residual mmio emulation
request to userspace").

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 36 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 633b22df46a4..267f2353e4ab 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1583,3 +1583,39 @@ void *addr_gva2hva(struct kvm_vm *vm, vm_vaddr_t gva)
 {
 	return addr_gpa2hva(vm, addr_gva2gpa(vm, gva));
 }
+
+/*
+ * Is Unrestricted Guest
+ *
+ * Input Args:
+ *   vm - Virtual Machine
+ *
+ * Output Args: None
+ *
+ * Return: True if the unrestricted guest is set to 'Y', otherwise return false.
+ *
+ * Check if the unrestricted guest flag is enabled.
+ */
+bool vm_is_unrestricted_guest(struct kvm_vm *vm)
+{
+	char val = 'N';
+	size_t count;
+	FILE *f;
+
+	if (vm == NULL) {
+		/* Ensure that the KVM vendor-specific module is loaded. */
+		f = fopen(KVM_DEV_PATH, "r");
+		TEST_ASSERT(f != NULL, "Error in opening KVM dev file: %d",
+			    errno);
+		fclose(f);
+	}
+
+	f = fopen("/sys/module/kvm_intel/parameters/unrestricted_guest", "r");
+	if (f) {
+		count = fread(&val, sizeof(char), 1, f);
+		TEST_ASSERT(count == 1, "Unable to read from param file.");
+		fclose(f);
+	}
+
+	return val == 'Y';
+}