1 files changed, 131 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
new file mode 100644
index 000000000000..5abecf06329e
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * vmx_apic_access_test
+ *
+ * Copyright (C) 2020, Google LLC.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ *
+ * The first subtest simply checks to see that an L2 guest can be
+ * launched with a valid APIC-access address that is backed by a
+ * page of L1 physical memory.
+ *
+ * The second subtest sets the APIC-access address to a (valid) L1
+ * physical address that is not backed by memory. KVM can't handle
+ * this situation, so resuming L2 should result in a KVM exit for
+ * internal error (emulation). This is not an architectural
+ * requirement. It is just a shortcoming of KVM. The internal error
+ * is unfortunate, but it's better than what used to happen!
+ */
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+#include "vmx.h"
+
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include "kselftest.h"
+
+static void l2_guest_code(void)
+{
+	/* Exit to L1 */
+	__asm__ __volatile__("vmcall");
+}
+
+static void l1_guest_code(struct vmx_pages *vmx_pages, unsigned long high_gpa)
+{
+#define L2_GUEST_STACK_SIZE 64
+	unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+	uint32_t control;
+
+	GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
+	GUEST_ASSERT(load_vmcs(vmx_pages));
+
+	/* Prepare the VMCS for L2 execution. */
+	prepare_vmcs(vmx_pages, l2_guest_code,
+		     &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+	control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
+	control |= CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
+	vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
+	control = vmreadz(SECONDARY_VM_EXEC_CONTROL);
+	control |= SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+	vmwrite(SECONDARY_VM_EXEC_CONTROL, control);
+	vmwrite(APIC_ACCESS_ADDR, vmx_pages->apic_access_gpa);
+
+	/* Try to launch L2 with the memory-backed APIC-access address. */
+	GUEST_SYNC(vmreadz(APIC_ACCESS_ADDR));
+	GUEST_ASSERT(!vmlaunch());
+	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
+
+	vmwrite(APIC_ACCESS_ADDR, high_gpa);
+
+	/* Try to resume L2 with the unbacked APIC-access address. */
+	GUEST_SYNC(vmreadz(APIC_ACCESS_ADDR));
+	GUEST_ASSERT(!vmresume());
+	GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
+
+	GUEST_DONE();
+}
+
+int main(int argc, char *argv[])
+{
+	unsigned long apic_access_addr = ~0ul;
+	vm_vaddr_t vmx_pages_gva;
+	unsigned long high_gpa;
+	struct vmx_pages *vmx;
+	bool done = false;
+
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_VMX));
+
+	vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
+
+	high_gpa = (vm->max_gfn - 1) << vm->page_shift;
+
+	vmx = vcpu_alloc_vmx(vm, &vmx_pages_gva);
+	prepare_virtualize_apic_accesses(vmx, vm);
+	vcpu_args_set(vcpu, 2, vmx_pages_gva, high_gpa);
+
+	while (!done) {
+		volatile struct kvm_run *run = vcpu->run;
+		struct ucall uc;
+
+		vcpu_run(vcpu);
+		if (apic_access_addr == high_gpa) {
+			TEST_ASSERT(run->exit_reason ==
+				    KVM_EXIT_INTERNAL_ERROR,
+				    "Got exit reason other than KVM_EXIT_INTERNAL_ERROR: %u (%s)\n",
+				    run->exit_reason,
+				    exit_reason_str(run->exit_reason));
+			TEST_ASSERT(run->internal.suberror ==
+				    KVM_INTERNAL_ERROR_EMULATION,
+				    "Got internal suberror other than KVM_INTERNAL_ERROR_EMULATION: %u\n",
+				    run->internal.suberror);
+			break;
+		}
+		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+			    "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
+			    run->exit_reason,
+			    exit_reason_str(run->exit_reason));
+
+		switch (get_ucall(vcpu, &uc)) {
+		case UCALL_ABORT:
+			REPORT_GUEST_ASSERT(uc);
+			/* NOT REACHED */
+		case UCALL_SYNC:
+			apic_access_addr = uc.args[1];
+			break;
+		case UCALL_DONE:
+			done = true;
+			break;
+		default:
+			TEST_ASSERT(false, "Unknown ucall %lu", uc.cmd);
+		}
+	}
+	kvm_vm_free(vm);
+	return 0;
+}