Add safe_halt() and cli() helpers to processor.h to make them broadly available in KVM selftests.

Suggested-by: Sean Christopherson seanjc@google.com Signed-off-by: Manali Shukla manali.shukla@amd.com --- .../selftests/kvm/include/x86_64/processor.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h index 20c9e3b33b07..6de37f6b8ddc 100644 --- a/tools/testing/selftests/kvm/include/x86_64/processor.h +++ b/tools/testing/selftests/kvm/include/x86_64/processor.h @@ -1217,6 +1217,23 @@ static inline void kvm_hypercall_map_gpa_range(uint64_t gpa, uint64_t size, GUEST_ASSERT(!ret); }

+/* + * Execute HLT in an STI interrupt shadow to ensure that a pending IRQ that's + * intended to be a wake event arrives *after* HLT is executed. Modern CPUs, + * except for a few oddballs that KVM is unlikely to run on, block IRQs for one + * instruction after STI, *if* RFLAGS.IF=0 before STI. Note, Intel CPUs may + * block other events beyond regular IRQs, e.g. may block NMIs and SMIs too. + */ +static inline void safe_halt(void) +{ + asm volatile("sti; hlt"); +} + +static inline void cli(void) +{ + asm volatile ("cli"); +} + void __vm_xsave_require_permission(uint64_t xfeature, const char *name);

#define vm_xsave_require_permission(xfeature) \

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 | 119 ++++++++++++++++++ 2 files changed, 120 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..4cc6a09906a2 --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/halt_disable_exit_test.c @@ -0,0 +1,119 @@ +// 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 "processor.h" +#include "test_util.h" + +#define SIG_IPI SIGUSR1 +static pthread_t task_thread, vcpu_thread; + +static void guest_code(uint64_t *is_hlt_exec) +{ + while (!READ_ONCE(*is_hlt_exec)) + ; + + safe_halt(); + GUEST_DONE(); +} + +static void *task_worker(void *arg) +{ + uint64_t *is_hlt_exec = (uint64_t *)arg; + + usleep(100000); + 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; + struct kvm_vcpu *vcpu = (struct kvm_vcpu *) arg; + struct kvm_run *run; + + struct kvm_signal_mask *sigmask = alloca(offsetof(struct kvm_signal_mask, sigset) + + sizeof(sigset_t)); + sigset_t *sigset = (sigset_t *) &sigmask->sigset; + + /* + * 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); + return 0; +} + +int main(int argc, char *argv[]) +{ + vm_vaddr_t hlt_vm_addr; + + struct kvm_vm *vm; + struct kvm_vcpu *vcpu; + uint64_t *host_hlt_addr; + void *retval; + sigset_t sigset; + int ret; + + TEST_REQUIRE(kvm_has_cap(KVM_CAP_X86_DISABLE_EXITS)); + + /* Create a VM without in kernel APIC support */ + vm = __vm_create(VM_SHAPE_FLAGS(NO_IRQCHIP), 1, 0); + vm_enable_cap(vm, KVM_CAP_X86_DISABLE_EXITS, KVM_X86_DISABLE_EXITS_HLT); + vcpu = vm_vcpu_add(vm, 0, guest_code); + + + hlt_vm_addr = vm_vaddr_alloc_page(vm); + host_hlt_addr = (uint64_t *)addr_gva2hva(vm, hlt_vm_addr); + vcpu_args_set(vcpu, 1, hlt_vm_addr); + + /* 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, vcpu); + TEST_ASSERT(ret == 0, "pthread_create vcpu thread failed errno=%d", errno); + + ret = pthread_create(&task_thread, NULL, task_worker, host_hlt_addr); + TEST_ASSERT(ret == 0, "pthread_create task thread failed errno=%d", errno); + + ret = pthread_join(vcpu_thread, &retval); + TEST_ASSERT(ret == 0, "pthread_join on vcpu thread failed with errno=%d", ret); + + ret = pthread_join(task_thread, &retval); + TEST_ASSERT(ret == 0, "pthread_join on task thread failed with errno=%d", ret); + + kvm_vm_free(vm); + return 0; +}