From: Nikunj A Dadhania <nikunj@xxxxxxx>
Add a test case to verify the Bus Lock exit feature
The main thing that the selftest verifies is that when a Buslock is
generated in the guest context, the KVM_EXIT_X86_BUS_LOCK is triggered
for SVM or VMX when the KVM capability KVM_CAP_X86_BUS_LOCK_EXIT is
enabled.
This test case also verifies the Bus Lock exit in nested scenario.
Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx>
Co-developed-by: Manali Shukla <manali.shukla@xxxxxxx>
Signed-off-by: Manali Shukla <manali.shukla@xxxxxxx>
---
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/x86_64/kvm_buslock_test.c | 130 ++++++++++++++++++
2 files changed, 131 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/kvm_buslock_test.c
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 960cf6a77198..b2de61e4a213 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -81,6 +81,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/hyperv_svm_test
TEST_GEN_PROGS_x86_64 += x86_64/hyperv_tlb_flush
TEST_GEN_PROGS_x86_64 += x86_64/kvm_clock_test
TEST_GEN_PROGS_x86_64 += x86_64/kvm_pv_test
+TEST_GEN_PROGS_x86_64 += x86_64/kvm_buslock_test
TEST_GEN_PROGS_x86_64 += x86_64/monitor_mwait_test
TEST_GEN_PROGS_x86_64 += x86_64/nested_exceptions_test
TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test
diff --git a/tools/testing/selftests/kvm/x86_64/kvm_buslock_test.c b/tools/testing/selftests/kvm/x86_64/kvm_buslock_test.c
new file mode 100644
index 000000000000..82693520485c
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/kvm_buslock_test.c
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2024 Advanced Micro Devices, Inc.
+ */
+
+#include "test_util.h"
+#include "kvm_util.h"
+#include "processor.h"
+#include "svm_util.h"
+#include "vmx.h"
+
+#define NR_ITERATIONS 100
+#define L2_GUEST_STACK_SIZE 64
+
+struct buslock_test {
+ unsigned char pad[PAGE_SIZE - 2];
+ atomic_long_t val;
+} __packed;
+
+struct buslock_test test __aligned(PAGE_SIZE);
+
+static __always_inline void buslock_atomic_add(int i, atomic_long_t *v)
+{
+ asm volatile(LOCK_PREFIX "addl %1,%0"
+ : "+m" (v->counter)
+ : "ir" (i) : "memory");
+}
+
+static void buslock_add(void)
+{
+ /*
+ * Increment a page unaligned variable atomically.
+ * This should generate a bus lock exit.
+ */
+ for (int i = 0; i < NR_ITERATIONS; i++)
+ buslock_atomic_add(2, &test.val);
+}
+
+static void l2_guest_code(void)
+{
+ buslock_add();
+ GUEST_DONE();
+}
+
+static void l1_svm_code(struct svm_test_data *svm)
+{
+ unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+ struct vmcb *vmcb = svm->vmcb;
+
+ generic_svm_setup(svm, l2_guest_code,
+ &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+ run_guest(vmcb, svm->vmcb_gpa);
+ GUEST_ASSERT(vmcb->control.exit_code == SVM_EXIT_VMMCALL);
+ GUEST_DONE();
+}
+
+static void l1_vmx_code(struct vmx_pages *vmx)
+{
+ unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+
+ GUEST_ASSERT_EQ(prepare_for_vmx_operation(vmx), true);
+ GUEST_ASSERT_EQ(load_vmcs(vmx), true);
+
+ prepare_vmcs(vmx, NULL, &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+
+ GUEST_ASSERT(!vmwrite(GUEST_RIP, (u64)l2_guest_code));
+ GUEST_ASSERT(!vmlaunch());
+
+ GUEST_ASSERT_EQ(vmreadz(VM_EXIT_REASON), EXIT_REASON_VMCALL);
+ GUEST_DONE();
+}
+
+static void guest_code(void *test_data)
+{
+ buslock_add();
+
+ if (this_cpu_has(X86_FEATURE_SVM))
+ l1_svm_code(test_data);
+ else
+ l1_vmx_code(test_data);
+}
+
+int main(int argc, char *argv[])
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_run *run;
+ struct kvm_vm *vm;
+ vm_vaddr_t nested_test_data_gva;
+
+ TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM) || kvm_cpu_has(X86_FEATURE_VMX));
+ TEST_REQUIRE(kvm_has_cap(KVM_CAP_X86_BUS_LOCK_EXIT));
+
+ vm = vm_create(1);
+ vm_enable_cap(vm, KVM_CAP_X86_BUS_LOCK_EXIT, KVM_BUS_LOCK_DETECTION_EXIT);
+ vcpu = vm_vcpu_add(vm, 0, guest_code);
+
+ if (kvm_cpu_has(X86_FEATURE_SVM))
+ vcpu_alloc_svm(vm, &nested_test_data_gva);
+ else
+ vcpu_alloc_vmx(vm, &nested_test_data_gva);
+
+ vcpu_args_set(vcpu, 1, nested_test_data_gva);
+
+ run = vcpu->run;
+
+ for (;;) {
+ struct ucall uc;
+
+ vcpu_run(vcpu);
+
+ if (run->exit_reason == KVM_EXIT_IO) {
+ switch (get_ucall(vcpu, &uc)) {
+ case UCALL_ABORT:
+ REPORT_GUEST_ASSERT(uc);
+ /* NOT REACHED */
+ case UCALL_SYNC:
+ continue;
+ case UCALL_DONE:
+ goto done;
+ default:
+ TEST_FAIL("Unknown ucall 0x%lx.", uc.cmd);
+ }
+ }
+
+ TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_X86_BUS_LOCK);
+ }
+done:
+ kvm_vm_free(vm);
+ return 0;
+}
--
2.34.1
