RE: [RFC PATCH v5 6/6] KVM: selftests: Add tests for VM and vCPU cap KVM_CAP_X86_DISABLE_EXITS

Kechen Lu
2023-01-18T20:43:32Z

Hi Zhi,

My apologies, I think messed up on the test case 2 and 4 design here.
The test passed on my setup is probably because of my BIOS setting.

I will refactor this selftest.
Thanks!

BR,
Kechen

> -----Original Message-----
> From: Kechen Lu
> Sent: Wednesday, January 18, 2023 12:26 PM
> To: Zhi Wang <zhi.wang.linux@gmail.com>
> Cc: kvm@vger.kernel.org; seanjc@google.com; pbonzini@redhat.com;
> chao.gao@intel.com; shaoqin.huang@intel.com; vkuznets@redhat.com;
> linux-kernel@vger.kernel.org
> Subject: RE: [RFC PATCH v5 6/6] KVM: selftests: Add tests for VM and vCPU
> cap KVM_CAP_X86_DISABLE_EXITS
>
> Hi Zhi,
>
> Thanks for testing the patch series. Comments below.
>
> > -----Original Message-----
> > From: Zhi Wang <zhi.wang.linux@gmail.com>
> > Sent: Wednesday, January 18, 2023 12:03 PM
> > To: Kechen Lu <kechenl@nvidia.com>
> > Cc: kvm@vger.kernel.org; seanjc@google.com; pbonzini@redhat.com;
> > chao.gao@intel.com; shaoqin.huang@intel.com; vkuznets@redhat.com;
> > linux-kernel@vger.kernel.org
> > Subject: Re: [RFC PATCH v5 6/6] KVM: selftests: Add tests for VM and
> > vCPU cap KVM_CAP_X86_DISABLE_EXITS
> >
> > External email: Use caution opening links or attachments
> >
> >
> > On Fri, 13 Jan 2023 22:01:14 +0000
> > Kechen Lu <kechenl@nvidia.com> wrote:
> >
> > I think I figure out why this test case doesn't work:
> >
> > The 2nd case always hangs because:
> >
> > 1) Unlike the 1st case in which a halter and an IPI sender will be
> > created, there is only halter thread created in the 2nd case.
> > 2) The halter enables KVM_X86_DISABLE_EXITS_HLT. Thus, HLT will not
> > cause VMEXIT
> > 3) The halter stuck in the halter_waiting_guest_code().
> > data->hlt_count is always 1 and data->wake_count is always 0.
> > 4) In the main thread, you have test_vm_disable_exits_cap() ->
> > while (data->hlt_count < COUNT_HLT_EXITS);
> >
> > As data->hlt_count will never increase in the vcpu_thread, the main
> > thread always stuck in the while loop.
> >
> > Can you explain more about your thoughts of designing this test case?
>
> For this test case, we want to test for the VM-scoped
> KVM_CAP_X86_DISABLE_EXITS cap flags setting.
> So if we set KVM_X86_DISABLE_EXITS_HLT, there would be no halt vmexits,
> and what expect is the HLT instructions looping executed within guest halter
> vCPU thread, and not stuck here, no IPIs required to wake it up.
>
> Here is what I got for this test case running in an AMD machine.
> -------------------------------------
> Halter vCPU thread started
> vCPU thread running vCPU 0
> Halter vCPU had 0 HLT exits
> Guest records 10 HLTs executed
> -------------------------------------
>
> BR,
> Kechen
>
> >
> > > Add selftests for KVM cap KVM_CAP_X86_DISABLE_EXITS overriding
> flags
> > > in VM and vCPU scope both works as expected.
> > >
> > > Suggested-by: Chao Gao <chao.gao@intel.com>
> > > Suggested-by: Shaoqin Huang <shaoqin.huang@intel.com>
> > > Signed-off-by: Kechen Lu <kechenl@nvidia.com>
> > > ---
> > > tools/testing/selftests/kvm/Makefile | 1 +
> > > .../selftests/kvm/x86_64/disable_exits_test.c | 457
> > > ++++++++++++++++++
> > > 2 files changed, 458 insertions(+)
> > > create mode 100644
> > > tools/testing/selftests/kvm/x86_64/disable_exits_test.c
> > >
> > > diff --git a/tools/testing/selftests/kvm/Makefile
> > > b/tools/testing/selftests/kvm/Makefile
> > > index 1750f91dd936..eeeba35e2536 100644
> > > --- a/tools/testing/selftests/kvm/Makefile
> > > +++ b/tools/testing/selftests/kvm/Makefile
> > > @@ -114,6 +114,7 @@ TEST_GEN_PROGS_x86_64 +=
> > x86_64/sev_migrate_tests
> > > TEST_GEN_PROGS_x86_64 += x86_64/amx_test
> > > TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test
> > > TEST_GEN_PROGS_x86_64 += x86_64/triple_fault_event_test
> > > +TEST_GEN_PROGS_x86_64 += x86_64/disable_exits_test
> > > TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
> > > TEST_GEN_PROGS_x86_64 += demand_paging_test
> > > TEST_GEN_PROGS_x86_64 += dirty_log_test diff --git
> > > a/tools/testing/selftests/kvm/x86_64/disable_exits_test.c
> > > b/tools/testing/selftests/kvm/x86_64/disable_exits_test.c
> > > new file mode 100644
> > > index 000000000000..dceba3bcef5f
> > > --- /dev/null
> > > +++ b/tools/testing/selftests/kvm/x86_64/disable_exits_test.c
> > > @@ -0,0 +1,457 @@
> > > +// SPDX-License-Identifier: GPL-2.0-only
> > > +/*
> > > + * Test per-VM and per-vCPU disable exits cap
> > > + * 1) Per-VM scope
> > > + * 2) Per-vCPU scope
> > > + *
> > > + */
> > > +
> > > +#define _GNU_SOURCE /* for program_invocation_short_name */
> > #include
> > > +<pthread.h> #include <inttypes.h> #include <string.h> #include
> > > +<time.h> #include <sys/ioctl.h>
> > > +
> > > +#include "test_util.h"
> > > +#include "kvm_util.h"
> > > +#include "svm_util.h"
> > > +#include "vmx.h"
> > > +#include "processor.h"
> > > +#include "asm/kvm.h"
> > > +#include "linux/kvm.h"
> > > +
> > > +/* Arbitary chosen IPI vector value from sender to halter vCPU */
> > > +#define IPI_VECTOR 0xa5
> > > +/* Number of HLTs halter vCPU thread executes */
> > > +#define COUNT_HLT_EXITS 10
> > > +
> > > +struct guest_stats {
> > > + uint32_t halter_apic_id;
> > > + volatile uint64_t hlt_count;
> > > + volatile uint64_t wake_count;
> > > +};
> > > +
> > > +static u64 read_vcpu_stats_halt_exits(struct kvm_vcpu *vcpu) {
> > > + int i;
> > > + struct kvm_stats_header header;
> > > + u64 *stats_data;
> > > + u64 ret = 0;
> > > + struct kvm_stats_desc *stats_desc;
> > > + struct kvm_stats_desc *pdesc;
> > > + int stats_fd = vcpu_get_stats_fd(vcpu);
> > > +
> > > + read_stats_header(stats_fd, &header);
> > > + if (header.num_desc == 0) {
> > > + fprintf(stderr,
> > > + "Cannot read halt exits since no KVM stats defined\n");
> > > + return ret;
> > > + }
> > > +
> > > + stats_desc = read_stats_descriptors(stats_fd, &header);
> > > + for (i = 0; i < header.num_desc; ++i) {
> > > + pdesc = get_stats_descriptor(stats_desc, i, &header);
> > > + if (!strncmp(pdesc->name, "halt_exits", 10)) {
> > > + stats_data = malloc(pdesc->size * sizeof(*stats_data));
> > > + read_stat_data(stats_fd, &header, pdesc, stats_data,
> > > + pdesc->size);
> > > + ret = *stats_data;
> > > + free(stats_data);
> > > + break;
> > > + }
> > > + }
> > > + free(stats_desc);
> > > + return ret;
> > > +}
> > > +
> > > +/* HLT multiple times in one vCPU */ static void
> > > +halter_guest_code(struct guest_stats *data) {
> > > + xapic_enable();
> > > + data->halter_apic_id =
> > > +GET_APIC_ID_FIELD(xapic_read_reg(APIC_ID));
> > > +
> > > + for (;;) {
> > > + data->hlt_count++;
> > > + asm volatile("sti; hlt; cli");
> > > + data->wake_count++;
> > > + }
> > > +}
> > > +
> > > +static void halter_waiting_guest_code(struct guest_stats *data) {
> > > + uint64_t tsc_start = rdtsc();
> > > +
> > > + xapic_enable();
> > > + data->halter_apic_id =
> > > + GET_APIC_ID_FIELD(xapic_read_reg(APIC_ID));
> > > +
> > > + for (;;) {
> > > + data->hlt_count++;
> > > + asm volatile("sti; hlt; cli");
> > > + data->wake_count++;
> > > + /* Wait for ~0.5sec for each HLT execution */
> > > + tsc_start = rdtsc();
> > > + while (rdtsc() - tsc_start < 2000000000);
> > > + }
> > > +}
> > > +
> > > +/* Runs on halter vCPU when IPI arrives */ static void
> > > +guest_ipi_handler(struct ex_regs *regs) {
> > > + xapic_write_reg(APIC_EOI, 11); }
> > > +
> > > +/* Sender vCPU waits for ~1sec to assume HLT executed */ static
> > > +void sender_wait_loop(struct guest_stats *data, uint64_t
> old_hlt_count,
> > > + uint64_t old_wake_count) {
> > > + uint64_t tsc_start = rdtsc();
> > > + while (rdtsc() - tsc_start < 4000000000);
> > > + GUEST_ASSERT((data->wake_count != old_wake_count) &&
> > > + (data->hlt_count != old_hlt_count)); }
> > > +
> > > +/* Sender vCPU loops sending IPI to halter vCPU every ~1sec */
> > > +static void sender_guest_code(struct guest_stats *data) {
> > > + uint32_t icr_val;
> > > + uint32_t icr2_val;
> > > + uint64_t old_hlt_count = 0;
> > > + uint64_t old_wake_count = 0;
> > > +
> > > + xapic_enable();
> > > + /* Init interrupt command register for sending IPIs */
> > > + icr_val = (APIC_DEST_PHYSICAL | APIC_DM_FIXED | IPI_VECTOR);
> > > + icr2_val = SET_APIC_DEST_FIELD(data->halter_apic_id);
> > > +
> > > + for (;;) {
> > > + /*
> > > + * Send IPI to halted vCPU
> > > + * First IPI sends here as already waited before sender vCPU
> > > + * thread creation
> > > + */
> > > + xapic_write_reg(APIC_ICR2, icr2_val);
> > > + xapic_write_reg(APIC_ICR, icr_val);
> > > + sender_wait_loop(data, old_hlt_count, old_wake_count);
> > > + GUEST_ASSERT((data->wake_count != old_wake_count) &&
> > > + (data->hlt_count != old_hlt_count));
> > > + old_wake_count = data->wake_count;
> > > + old_hlt_count = data->hlt_count;
> > > + }
> > > +}
> > > +
> > > +static void *vcpu_thread(void *arg) {
> > > + struct kvm_vcpu *vcpu = (struct kvm_vcpu *)arg;
> > > + int old;
> > > + int r;
> > > +
> > > + r = pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS,
> > &old);
> > > + TEST_ASSERT(r == 0,
> > > + "pthread_setcanceltype failed on vcpu_id=%u with errno=%d",
> > > + vcpu->id, r);
> > > + fprintf(stderr, "vCPU thread running vCPU %u\n", vcpu->id);
> > > + vcpu_run(vcpu);
> > > + return NULL;
> > > +}
> > > +
> > > +static void cancel_join_vcpu_thread(pthread_t thread, struct
> > > +kvm_vcpu
> > > +*vcpu) {
> > > + void *retval;
> > > + int r;
> > > +
> > > + r = pthread_cancel(thread);
> > > + TEST_ASSERT(r == 0,
> > > + "pthread_cancel on vcpu_id=%d failed with errno=%d",
> > > + vcpu->id, r);
> > > +
> > > + r = pthread_join(thread, &retval);
> > > + TEST_ASSERT(r == 0,
> > > + "pthread_join on vcpu_id=%d failed with errno=%d",
> > > + vcpu->id, r);
> > > +}
> > > +
> > > +/*
> > > + * Test case 1:
> > > + * Normal VM running with one vCPU keeps executing HLTs,
> > > + * another vCPU sending IPIs to wake it up, should expect
> > > + * all HLTs exiting to host
> > > + */
> > > +static void test_vm_without_disable_exits_cap(void)
> > > +{
> > > + int r;
> > > + int wait_secs;
> > > + const int first_halter_wait = 10;
> > > + uint64_t kvm_halt_exits;
> > > + struct kvm_vm *vm;
> > > + struct kvm_vcpu *halter_vcpu;
> > > + struct kvm_vcpu *sender_vcpu;
> > > + struct guest_stats *data;
> > > + vm_vaddr_t guest_stats_page_vaddr;
> > > + pthread_t threads[2];
> > > +
> > > + /* Create VM */
> > > + vm = vm_create(2);
> > > +
> > > + /* Add vCPU with loops halting */
> > > + halter_vcpu = vm_vcpu_add(vm, 0, halter_guest_code);
> > > +
> > > + vm_init_descriptor_tables(vm);
> > > + vcpu_init_descriptor_tables(halter_vcpu);
> > > + vm_install_exception_handler(vm, IPI_VECTOR, guest_ipi_handler);
> > > + virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA);
> > > +
> > > + /* Add vCPU with IPIs waking up halter vCPU */
> > > + sender_vcpu = vm_vcpu_add(vm, 1, sender_guest_code);
> > > +
> > > + guest_stats_page_vaddr = vm_vaddr_alloc_page(vm);
> > > + data = addr_gva2hva(vm, guest_stats_page_vaddr);
> > > + memset(data, 0, sizeof(*data));
> > > +
> > > + vcpu_args_set(halter_vcpu, 1, guest_stats_page_vaddr);
> > > + vcpu_args_set(sender_vcpu, 1, guest_stats_page_vaddr);
> > > +
> > > + /* Start halter vCPU thread and wait for it to execute first HLT. */
> > > + r = pthread_create(&threads[0], NULL, vcpu_thread, halter_vcpu);
> > > + TEST_ASSERT(r == 0,
> > > + "pthread_create halter failed errno=%d", errno);
> > > + fprintf(stderr, "Halter vCPU thread started\n");
> > > +
> > > + wait_secs = 0;
> > > + while ((wait_secs < first_halter_wait) && !data->hlt_count) {
> > > + sleep(1);
> > > + wait_secs++;
> > > + }
> > > + TEST_ASSERT(data->hlt_count,
> > > + "Halter vCPU did not execute first HLT within %d seconds",
> > > + first_halter_wait);
> > > + fprintf(stderr,
> > > + "Halter vCPU thread reported its first HLT executed "
> > > + "after %d seconds.\n",
> > > + wait_secs);
> > > +
> > > + /*
> > > + * After guest halter vCPU executed first HLT, start the sender
> > > + * vCPU thread to wakeup halter vCPU
> > > + */
> > > + r = pthread_create(&threads[1], NULL, vcpu_thread, sender_vcpu);
> > > + TEST_ASSERT(r == 0, "pthread_create sender failed errno=%d",
> > > + errno);
> > > +
> > > + while (data->hlt_count < COUNT_HLT_EXITS);
> > > +
> > > + cancel_join_vcpu_thread(threads[0], halter_vcpu);
> > > + cancel_join_vcpu_thread(threads[1], sender_vcpu);
> > > +
> > > + kvm_halt_exits = read_vcpu_stats_halt_exits(halter_vcpu);
> > > + TEST_ASSERT(kvm_halt_exits == data->hlt_count,
> > > + "Halter vCPU had unmatched %lu halt exits - %lu HLTs "
> > > + "executed, when not disabling VM halt exits\n",
> > > + kvm_halt_exits, data->hlt_count);
> > > + fprintf(stderr, "Halter vCPU had %lu halt exits\n",
> > > + kvm_halt_exits);
> > > + fprintf(stderr, "Guest records %lu HLTs executed, "
> > > + "waked %lu times\n",
> > > + data->hlt_count, data->wake_count);
> > > +
> > > + kvm_vm_free(vm);
> > > +}
> > > +
> > > +/*
> > > + * Test case 2:
> > > + * VM scoped exits disabling, HLT instructions
> > > + * stay inside guest without exits
> > > + */
> > > +static void test_vm_disable_exits_cap(void) {
> > > + int r;
> > > + uint64_t kvm_halt_exits;
> > > + struct kvm_vm *vm;
> > > + struct kvm_vcpu *halter_vcpu;
> > > + struct guest_stats *data;
> > > + vm_vaddr_t guest_stats_page_vaddr;
> > > + pthread_t halter_thread;
> > > +
> > > + /* Create VM */
> > > + vm = vm_create(1);
> > > +
> > > + /*
> > > + * Before adding any vCPUs, enable the KVM_X86_DISABLE_EXITS
> cap
> > > + * with flag KVM_X86_DISABLE_EXITS_HLT
> > > + */
> > > + vm_enable_cap(vm, KVM_CAP_X86_DISABLE_EXITS,
> > > + KVM_X86_DISABLE_EXITS_HLT);
> > > +
> > > + /* Add vCPU with loops halting */
> > > + halter_vcpu = vm_vcpu_add(vm, 0, halter_waiting_guest_code);
> > > +
> > > + vm_init_descriptor_tables(vm);
> > > + vcpu_init_descriptor_tables(halter_vcpu);
> > > + vm_install_exception_handler(vm, IPI_VECTOR, guest_ipi_handler);
> > > + virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA);
> > > +
> > > + guest_stats_page_vaddr = vm_vaddr_alloc_page(vm);
> > > + data = addr_gva2hva(vm, guest_stats_page_vaddr);
> > > + memset(data, 0, sizeof(*data));
> > > + vcpu_args_set(halter_vcpu, 1, guest_stats_page_vaddr);
> > > +
> > > + /* Start halter vCPU thread and execute HLTs immediately */
> > > + r = pthread_create(&halter_thread, NULL, vcpu_thread,
> halter_vcpu);
> > > + TEST_ASSERT(r == 0,
> > > + "pthread_create halter failed errno=%d", errno);
> > > + fprintf(stderr, "Halter vCPU thread started\n");
> > > +
> > > + while (data->hlt_count < COUNT_HLT_EXITS);
> > > +
> > > + cancel_join_vcpu_thread(halter_thread, halter_vcpu);
> > > +
> > > + kvm_halt_exits = read_vcpu_stats_halt_exits(halter_vcpu);
> > > + TEST_ASSERT(kvm_halt_exits == 0,
> > > + "Halter vCPU had unexpected halt exits occuring after "
> > > + "disabling VM-scoped halt exits cap\n");
> > > + fprintf(stderr, "Halter vCPU had %lu HLT exits\n",
> > > + kvm_halt_exits);
> > > + fprintf(stderr, "Guest records %lu HLTs executed\n",
> > > + data->hlt_count);
> > > +
> > > + kvm_vm_free(vm);
> > > +}
> > > +
> > > +/*
> > > + * Test case 3:
> > > + * VM overrides exits disable flags after vCPU created,
> > > + * which is not allowed
> > > + */
> > > +static void test_vm_disable_exits_cap_with_vcpu_created(void)
> > > +{
> > > + int r;
> > > + struct kvm_vm *vm;
> > > + struct kvm_enable_cap cap = {
> > > + .cap = KVM_CAP_X86_DISABLE_EXITS,
> > > + .args[0] = KVM_X86_DISABLE_EXITS_HLT |
> > KVM_X86_DISABLE_EXITS_OVERRIDE,
> > > + };
> > > +
> > > + /* Create VM */
> > > + vm = vm_create(1);
> > > + /* Add vCPU with loops halting */
> > > + vm_vcpu_add(vm, 0, halter_waiting_guest_code);
> > > +
> > > + /*
> > > + * After creating vCPU, the current VM-scoped ABI should
> > > + * discard the cap enable of KVM_CAP_X86_DISABLE_EXITS
> > > + * and return non-zero. Since vm_enabled_cap() not able
> > > + * to assert the return value, so use the __vm_ioctl()
> > > + */
> > > + r = __vm_ioctl(vm, KVM_ENABLE_CAP, &cap);
> > > +
> > > + TEST_ASSERT(r != 0,
> > > + "Setting VM-scoped KVM_CAP_X86_DISABLE_EXITS after "
> > > + "vCPUs created is not allowed, but it succeeds
> > > +here\n"); }
> > > +
> > > +/*
> > > + * Test case 4:
> > > + * vCPU scoped halt exits disabling and enabling tests,
> > > + * verify overides are working after vCPU created */ static void
> > > +test_vcpu_toggling_disable_exits_cap(void)
> > > +{
> > > + int r;
> > > + uint64_t kvm_halt_exits;
> > > + struct kvm_vm *vm;
> > > + struct kvm_vcpu *halter_vcpu;
> > > + struct kvm_vcpu *sender_vcpu;
> > > + struct guest_stats *data;
> > > + vm_vaddr_t guest_stats_page_vaddr;
> > > + pthread_t threads[2];
> > > +
> > > + /* Create VM */
> > > + vm = vm_create(2);
> > > +
> > > + /* Add vCPU with loops halting */
> > > + halter_vcpu = vm_vcpu_add(vm, 0, halter_waiting_guest_code);
> > > + /* Set KVM_CAP_X86_DISABLE_EXITS_HLT for halter vCPU */
> > > + vcpu_enable_cap(halter_vcpu, KVM_CAP_X86_DISABLE_EXITS,
> > > + KVM_X86_DISABLE_EXITS_HLT |
> > > + KVM_X86_DISABLE_EXITS_OVERRIDE);
> > > +
> > > + vm_init_descriptor_tables(vm);
> > > + vcpu_init_descriptor_tables(halter_vcpu);
> > > + vm_install_exception_handler(vm, IPI_VECTOR,
> > > + guest_ipi_handler);
> > > +
> > > + virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA);
> > > +
> > > + /* Add vCPU with IPIs waking up halter vCPU */
> > > + sender_vcpu = vm_vcpu_add(vm, 1, sender_guest_code);
> > > +
> > > + guest_stats_page_vaddr = vm_vaddr_alloc_page(vm);
> > > + data = addr_gva2hva(vm, guest_stats_page_vaddr);
> > > + memset(data, 0, sizeof(*data));
> > > +
> > > + vcpu_args_set(halter_vcpu, 1, guest_stats_page_vaddr);
> > > + vcpu_args_set(sender_vcpu, 1, guest_stats_page_vaddr);
> > > +
> > > + r = pthread_create(&threads[0], NULL, vcpu_thread, halter_vcpu);
> > > + TEST_ASSERT(r == 0,
> > > + "pthread_create halter failed errno=%d", errno);
> > > + fprintf(stderr, "Halter vCPU thread started with halt exits"
> > > + "disabled\n");
> > > +
> > > + /*
> > > + * For the first phase of the running, halt exits
> > > + * are disabled, halter vCPU executes HLT instruction
> > > + * but never exits to host
> > > + */
> > > + while (data->hlt_count < (COUNT_HLT_EXITS / 2));
> > > +
> > > + cancel_join_vcpu_thread(threads[0], halter_vcpu);
> > > + /*
> > > + * Override and clean KVM_CAP_X86_DISABLE_EXITS flags
> > > + * for halter vCPU. Expect to see halt exits occurs then.
> > > + */
> > > + vcpu_enable_cap(halter_vcpu, KVM_CAP_X86_DISABLE_EXITS,
> > > + KVM_X86_DISABLE_EXITS_OVERRIDE);
> > > +
> > > + r = pthread_create(&threads[0], NULL, vcpu_thread, halter_vcpu);
> > > + TEST_ASSERT(r == 0,
> > > + "pthread_create halter failed errno=%d", errno);
> > > + fprintf(stderr, "Halter vCPU thread restarted and cleared "
> > > + "halt exits flag\n");
> > > +
> > > + sleep(1);
> > > + /*
> > > + * Second phase of the test, after guest halter vCPU
> > > + * reenabled halt exits, start the sender
> > > + * vCPU thread to wakeup halter vCPU
> > > + */
> > > + r = pthread_create(&threads[1], NULL, vcpu_thread, sender_vcpu);
> > > + TEST_ASSERT(r == 0, "pthread_create sender failed errno=%d",
> > > + errno);
> > > +
> > > + while (data->hlt_count < COUNT_HLT_EXITS);
> > > +
> > > + cancel_join_vcpu_thread(threads[0], halter_vcpu);
> > > + cancel_join_vcpu_thread(threads[1], sender_vcpu);
> > > +
> > > + kvm_halt_exits = read_vcpu_stats_halt_exits(halter_vcpu);
> > > + TEST_ASSERT(kvm_halt_exits == (COUNT_HLT_EXITS / 2),
> > > + "Halter vCPU had unexpected %lu halt exits, "
> > > + "there should be %d halt exits while "
> > > + "not disabling VM halt exits\n",
> > > + kvm_halt_exits, COUNT_HLT_EXITS / 2);
> > > + fprintf(stderr, "Halter vCPU had %lu halt exits\n",
> > > + kvm_halt_exits);
> > > + fprintf(stderr, "Guest records %lu HLTs executed, "
> > > + "waked %lu times\n",
> > > + data->hlt_count, data->wake_count);
> > > +
> > > + kvm_vm_free(vm);
> > > +}
> > > +
> > > +int main(int argc, char *argv[])
> > > +{
> > > + fprintf(stderr, "VM-scoped tests start\n");
> > > + test_vm_without_disable_exits_cap();
> > > + test_vm_disable_exits_cap();
> > > + test_vm_disable_exits_cap_with_vcpu_created();
> > > + fprintf(stderr, "vCPU-scoped test starts\n");
> > > + test_vcpu_toggling_disable_exits_cap();
> > > + return 0;
> > > +}