[PATCH v1 3/3] KVM: selftests: Add a test case for KVM_X86_DISABLE_EXITS_HLT

[Manali Shukla <manali.shukla@amd.com>]

By default, HLT instruction executed by guest is intercepted by hypervisor.
However, KVM_CAP_X86_DISABLE_EXITS capability can be used to not intercept
HLT by setting KVM_X86_DISABLE_EXITS_HLT.

Add a test case to test KVM_X86_DISABLE_EXITS_HLT functionality.

Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Manali Shukla <manali.shukla@amd.com>
---
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../kvm/x86_64/halt_disable_exit_test.c       | 113 ++++++++++++++++++
 2 files changed, 114 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/x86_64/halt_disable_exit_test.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c75251d5c97c..9f72abb95d2e 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -89,6 +89,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/set_sregs_test
 TEST_GEN_PROGS_x86_64 += x86_64/smaller_maxphyaddr_emulation_test
 TEST_GEN_PROGS_x86_64 += x86_64/smm_test
 TEST_GEN_PROGS_x86_64 += x86_64/state_test
+TEST_GEN_PROGS_x86_64 += x86_64/halt_disable_exit_test
 TEST_GEN_PROGS_x86_64 += x86_64/vmx_preemption_timer_test
 TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test
 TEST_GEN_PROGS_x86_64 += x86_64/svm_int_ctl_test
diff --git a/tools/testing/selftests/kvm/x86_64/halt_disable_exit_test.c b/tools/testing/selftests/kvm/x86_64/halt_disable_exit_test.c
new file mode 100644
index 000000000000..b7279dd0eaff
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/halt_disable_exit_test.c
@@ -0,0 +1,113 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KVM disable halt exit test
+ *
+ *  Copyright (C) 2024 Advanced Micro Devices, Inc.
+ */
+#include <pthread.h>
+#include <signal.h>
+#include "kvm_util.h"
+#include "svm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+pthread_t task_thread, vcpu_thread;
+#define SIG_IPI SIGUSR1
+
+static void guest_code(uint8_t is_hlt_exec)
+{
+	while (!READ_ONCE(is_hlt_exec))
+		;
+
+	safe_halt();
+	GUEST_DONE();
+}
+
+static void *task_worker(void *arg)
+{
+	uint8_t *is_hlt_exec = (uint8_t *)arg;
+
+	usleep(1000);
+	WRITE_ONCE(*is_hlt_exec, 1);
+	pthread_kill(vcpu_thread, SIG_IPI);
+	return 0;
+}
+
+static void *vcpu_worker(void *arg)
+{
+	int ret;
+	int sig = -1;
+	uint8_t *is_hlt_exec = (uint8_t *)arg;
+	struct kvm_vm *vm;
+	struct kvm_run *run;
+	struct kvm_vcpu *vcpu;
+	struct kvm_signal_mask *sigmask = alloca(offsetof(struct kvm_signal_mask, sigset)
+						 + sizeof(sigset_t));
+	sigset_t *sigset = (sigset_t *) &sigmask->sigset;
+
+	/* Create a VM without in kernel APIC support */
+	vm = __vm_create(VM_SHAPE_DEFAULT, 1, 0, false);
+	vm_enable_cap(vm, KVM_CAP_X86_DISABLE_EXITS, KVM_X86_DISABLE_EXITS_HLT);
+	vcpu = vm_vcpu_add(vm, 0, guest_code);
+	vcpu_args_set(vcpu, 1, *is_hlt_exec);
+
+	/*
+	 * SIG_IPI is unblocked atomically while in KVM_RUN.  It causes the
+	 * ioctl to return with -EINTR, but it is still pending and we need
+	 * to accept it with the sigwait.
+	 */
+	sigmask->len = 8;
+	pthread_sigmask(0, NULL, sigset);
+	sigdelset(sigset, SIG_IPI);
+	vcpu_ioctl(vcpu, KVM_SET_SIGNAL_MASK, sigmask);
+	sigemptyset(sigset);
+	sigaddset(sigset, SIG_IPI);
+	run = vcpu->run;
+
+again:
+	ret = __vcpu_run(vcpu);
+	TEST_ASSERT_EQ(errno, EINTR);
+
+	if (ret == -1 && errno == EINTR) {
+		sigwait(sigset, &sig);
+		assert(sig == SIG_IPI);
+		TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_INTR);
+		goto again;
+	}
+
+	if (run->exit_reason == KVM_EXIT_HLT)
+		TEST_FAIL("Expected KVM_EXIT_INTR, got KVM_EXIT_HLT");
+
+	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
+	kvm_vm_free(vm);
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	int ret;
+	void *retval;
+	uint8_t is_halt_exec;
+	sigset_t sigset;
+
+	TEST_REQUIRE(kvm_has_cap(KVM_CAP_X86_DISABLE_EXITS));
+
+	/* Ensure that vCPU threads start with SIG_IPI blocked.  */
+	sigemptyset(&sigset);
+	sigaddset(&sigset, SIG_IPI);
+	pthread_sigmask(SIG_BLOCK, &sigset, NULL);
+
+	ret = pthread_create(&vcpu_thread, NULL, vcpu_worker, &is_halt_exec);
+	TEST_ASSERT(ret == 0, "pthread_create vcpu thread failed errno=%d", errno);
+
+	ret = pthread_create(&task_thread, NULL, task_worker, &is_halt_exec);
+	TEST_ASSERT(ret == 0, "pthread_create task thread failed errno=%d", errno);
+
+	pthread_join(vcpu_thread, &retval);
+	TEST_ASSERT(ret == 0, "pthread_join on vcpu thread failed with errno=%d", ret);
+
+	pthread_join(task_thread, &retval);
+	TEST_ASSERT(ret == 0, "pthread_join on task thread failed with errno=%d", ret);
+
+	return 0;
+}
-- 
2.34.1