// SPDX-License-Identifier: GPL-2.0
/*
* xapic_ipi_test
*
* Copyright (C) 2020, Google LLC.
*
* This work is licensed under the terms of the GNU GPL, version 2.
*
* Test that when the APIC is in xAPIC mode, a vCPU can send an IPI to wake
* another vCPU that is halted when KVM's backing page for the APIC access
* address has been moved by mm.
*
* The test starts two vCPUs: one that sends IPIs and one that continually
* executes HLT. The sender checks that the halter has woken from the HLT and
* has reentered HLT before sending the next IPI. While the vCPUs are running,
* the host continually calls migrate_pages to move all of the process' pages
* amongst the available numa nodes on the machine.
*
* Migration is a command line option. When used on non-numa machines will
* exit with error. Test is still usefull on non-numa for testing IPIs.
*/
#define _GNU_SOURCE /* for program_invocation_short_name */
#include <getopt.h>
#include <pthread.h>
#include <inttypes.h>
#include <string.h>
#include <time.h>
#include "kvm_util.h"
#include "numaif.h"
#include "processor.h"
#include "test_util.h"
#include "vmx.h"
/* Default running time for the test */
#define DEFAULT_RUN_SECS 3
/* Default delay between migrate_pages calls (microseconds) */
#define DEFAULT_DELAY_USECS 500000
/*
* Vector for IPI from sender vCPU to halting vCPU.
* Value is arbitrary and was chosen for the alternating bit pattern. Any
* value should work.
*/
#define IPI_VECTOR 0xa5
/*
* Incremented in the IPI handler. Provides evidence to the sender that the IPI
* arrived at the destination
*/
static volatile uint64_t ipis_rcvd;
/* Data struct shared between host main thread and vCPUs */
struct test_data_page {
uint32_t halter_apic_id;
volatile uint64_t hlt_count;
volatile uint64_t wake_count;
uint64_t ipis_sent;
uint64_t migrations_attempted;
uint64_t migrations_completed;
uint32_t icr;
uint32_t icr2;
uint32_t halter_tpr;
uint32_t halter_ppr;
/*
* Record local version register as a cross-check that APIC access
* worked. Value should match what KVM reports (APIC_VERSION in
* arch/x86/kvm/lapic.c). If test is failing, check that values match
* to determine whether APIC access exits are working.
*/
uint32_t halter_lvr;
};
struct thread_params {
struct test_data_page *data;
struct kvm_vcpu *vcpu;
uint64_t *pipis_rcvd; /* host address of ipis_rcvd global */
};
void verify_apic_base_addr(void)
{
uint64_t msr = rdmsr(MSR_IA32_APICBASE);
uint64_t base = GET_APIC_BASE(msr);
GUEST_ASSERT(base == APIC_DEFAULT_GPA);
}
static void halter_guest_code(struct test_data_page *data)
{
verify_apic_base_addr();
xapic_enable();
data->halter_apic_id = GET_APIC_ID_FIELD(xapic_read_reg(APIC_ID));
data->halter_lvr = xapic_read_reg(APIC_LVR);
/*
* Loop forever HLTing and recording halts & wakes. Disable interrupts
* each time around to minimize window between signaling the pending
* halt to the sender vCPU and executing the halt. No need to disable on
* first run as this vCPU executes first and the host waits for it to
* signal going into first halt before starting the sender vCPU. Record
* TPR and PPR for diagnostic purposes in case the test fails.
*/
for (;;) {
data->halter_tpr = xapic_read_reg(APIC_TASKPRI);
data->halter_ppr = xapic_read_reg(APIC_PROCPRI);
data->hlt_count++;
asm volatile("sti; hlt; cli");
data->wake_count++;
}
}
/*
* Runs on halter vCPU when IPI arrives. Write an arbitrary non-zero value to
* enable diagnosing errant writes to the APIC access address backing page in
* case of test failure.
*/
static void guest_ipi_handler(struct ex_regs *regs)
{
ipis_rcvd++;
xapic_write_reg(APIC_EOI, 77);
}
static void sender_guest_code(struct test_data_page *data)
{
uint64_t last_wake_count;
uint64_t last_hlt_count;
uint64_t last_ipis_rcvd_count;
uint32_t icr_val;
uint32_t icr2_val;
uint64_t tsc_start;
verify_apic_base_addr();
xapic_enable();
/*
* Init interrupt command register for sending IPIs
*
* Delivery mode=fixed, per SDM:
* "Delivers the interrupt specified in the vector field to the target
* processor."
*
* Destination mode=physical i.e. specify target by its local APIC
* ID. This vCPU assumes that the halter vCPU has already started and
* set data->halter_apic_id.
*/
icr_val = (APIC_DEST_PHYSICAL | APIC_DM_FIXED | IPI_VECTOR);
icr2_val = SET_APIC_DEST_FIELD(data->halter_apic_id);
data->icr = icr_val;
data->icr2 = icr2_val;
last_wake_count = data->wake_count;
last_hlt_count = data->hlt_count;
last_ipis_rcvd_count = ipis_rcvd;
for (;;) {
/*
* Send IPI to halter vCPU.
* First IPI can be sent unconditionally because halter vCPU
* starts earlier.
*/
xapic_write_reg(APIC_ICR2, icr2_val);
xapic_write_reg(APIC_ICR, icr_val);
data->ipis_sent++;
/*
* Wait up to ~1 sec for halter to indicate that it has:
* 1. Received the IPI
* 2. Woken up from the halt
* 3. Gone back into halt
* Current CPUs typically run at 2.x Ghz which is ~2
* billion ticks per second.
*/
tsc_start = rdtsc();
while (rdtsc() - tsc_start < 2000000000) {
if ((ipis_rcvd != last_ipis_rcvd_count) &&
(data->wake_count != last_wake_count) &&
(data->hlt_count != last_hlt_count))
break;
}
GUEST_ASSERT((ipis_rcvd != last_ipis_rcvd_count) &&
(data->wake_count != last_wake_count) &&
(data->hlt_count != last_hlt_count));
last_wake_count = data->wake_count;
last_hlt_count = data->hlt_count;
last_ipis_rcvd_count = ipis_rcvd;
}
}
static void *vcpu_thread(void *arg)
{
struct thread_params *params = (struct thread_params *)arg;
struct kvm_vcpu *vcpu = params->vcpu;
struct ucall uc;
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);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
if (get_ucall(vcpu, &uc) == UCALL_ABORT) {
TEST_ASSERT(false,
"vCPU %u exited with error: %s.\n"
"Sending vCPU sent %lu IPIs to halting vCPU\n"
"Halting vCPU halted %lu times, woke %lu times, received %lu IPIs.\n"
"Halter TPR=%#x PPR=%#x LVR=%#x\n"
"Migrations attempted: %lu\n"
"Migrations completed: %lu\n",
vcpu->id, (const char *)uc.args[0],
params->data->ipis_sent, params->data->hlt_count,
params->data->wake_count,
*params->pipis_rcvd, params->data->halter_tpr,
params->data->halter_ppr, params->data->halter_lvr,
params->data->migrations_attempted,
params->data->migrations_completed);
}
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_ASSERT(retval == PTHREAD_CANCELED,
"expected retval=%p, got %p", PTHREAD_CANCELED,
retval);
}
void do_migrations(struct test_data_page *data, int run_secs, int delay_usecs,
uint64_t *pipis_rcvd)
{
long pages_not_moved;
unsigned long nodemask = 0;
unsigned long nodemasks[sizeof(nodemask) * 8];
int nodes = 0;
time_t start_time, last_update, now;
time_t interval_secs = 1;
int i, r;
int from, to;
unsigned long bit;
uint64_t hlt_count;
uint64_t wake_count;
uint64_t ipis_sent;
fprintf(stderr, "Calling migrate_pages every %d microseconds\n",
delay_usecs);
/* Get set of first 64 numa nodes available */
r = get_mempolicy(NULL, &nodemask, sizeof(nodemask) * 8,
0, MPOL_F_MEMS_ALLOWED);
TEST_ASSERT(r == 0, "get_mempolicy failed errno=%d", errno);
fprintf(stderr, "Numa nodes found amongst first %lu possible nodes "
"(each 1-bit indicates node is present): %#lx\n",
sizeof(nodemask) * 8, nodemask);
/* Init array of masks containing a single-bit in each, one for each
* available node. migrate_pages called below requires specifying nodes
* as bit masks.
*/
for (i = 0, bit = 1; i < sizeof(nodemask) * 8; i++, bit <<= 1) {
if (nodemask & bit) {
nodemasks[nodes] = nodemask & bit;
nodes++;
}
}
TEST_ASSERT(nodes > 1,
"Did not find at least 2 numa nodes. Can't do migration\n");
fprintf(stderr, "Migrating amongst %d nodes found\n", nodes);
from = 0;
to = 1;
start_time = time(NULL);
last_update = start_time;
ipis_sent = data->ipis_sent;
hlt_count = data->hlt_count;
wake_count = data->wake_count;
while ((int)(time(NULL) - start_time) < run_secs) {
data->migrations_attempted++;
/*
* migrate_pages with PID=0 will migrate all pages of this
* process between the nodes specified as bitmasks. The page
* backing the APIC access address belongs to this process
* because it is allocated by KVM in the context of the
* KVM_CREATE_VCPU ioctl. If that assumption ever changes this
* test may break or give a false positive signal.
*/
pages_not_moved = migrate_pages(0, sizeof(nodemasks[from]),
&nodemasks[from],
&nodemasks[to]);
if (pages_not_moved < 0)
fprintf(stderr,
"migrate_pages failed, errno=%d\n", errno);
else if (pages_not_moved > 0)
fprintf(stderr,
"migrate_pages could not move %ld pages\n",
pages_not_moved);
else
data->migrations_completed++;
from = to;
to++;
if (to == nodes)
to = 0;
now = time(NULL);
if (((now - start_time) % interval_secs == 0) &&
(now != last_update)) {
last_update = now;
fprintf(stderr,
"%lu seconds: Migrations attempted=%lu completed=%lu, "
"IPIs sent=%lu received=%lu, HLTs=%lu wakes=%lu\n",
now - start_time, data->migrations_attempted,
data->migrations_completed,
data->ipis_sent, *pipis_rcvd,
data->hlt_count, data->wake_count);
TEST_ASSERT(ipis_sent != data->ipis_sent &&
hlt_count != data->hlt_count &&
wake_count != data->wake_count,
"IPI, HLT and wake count have not increased "
"in the last %lu seconds. "
"HLTer is likely hung.\n", interval_secs);
ipis_sent = data->ipis_sent;
hlt_count = data->hlt_count;
wake_count = data->wake_count;
}
usleep(delay_usecs);
}
}
void get_cmdline_args(int argc, char *argv[], int *run_secs,
bool *migrate, int *delay_usecs)
{
for (;;) {
int opt = getopt(argc, argv, "s:d:m");
if (opt == -1)
break;
switch (opt) {
case 's':
*run_secs = parse_size(optarg);
break;
case 'm':
*migrate = true;
break;
case 'd':
*delay_usecs = parse_size(optarg);
break;
default:
TEST_ASSERT(false,
"Usage: -s <runtime seconds>. Default is %d seconds.\n"
"-m adds calls to migrate_pages while vCPUs are running."
" Default is no migrations.\n"
"-d <delay microseconds> - delay between migrate_pages() calls."
" Default is %d microseconds.\n",
DEFAULT_RUN_SECS, DEFAULT_DELAY_USECS);
}
}
}
int main(int argc, char *argv[])
{
int r;
int wait_secs;
const int max_halter_wait = 10;
int run_secs = 0;
int delay_usecs = 0;
struct test_data_page *data;
vm_vaddr_t test_data_page_vaddr;
bool migrate = false;
pthread_t threads[2];
struct thread_params params[2];
struct kvm_vm *vm;
uint64_t *pipis_rcvd;
get_cmdline_args(argc, argv, &run_secs, &migrate, &delay_usecs);
if (run_secs <= 0)
run_secs = DEFAULT_RUN_SECS;
if (delay_usecs <= 0)
delay_usecs = DEFAULT_DELAY_USECS;
vm = vm_create_with_one_vcpu(¶ms[0].vcpu, halter_guest_code);
vm_init_descriptor_tables(vm);
vcpu_init_descriptor_tables(params[0].vcpu);
vm_install_exception_handler(vm, IPI_VECTOR, guest_ipi_handler);
virt_pg_map(vm, APIC_DEFAULT_GPA, APIC_DEFAULT_GPA);
params[1].vcpu = vm_vcpu_add(vm, 1, sender_guest_code);
test_data_page_vaddr = vm_vaddr_alloc_page(vm);
data = addr_gva2hva(vm, test_data_page_vaddr);
memset(data, 0, sizeof(*data));
params[0].data = data;
params[1].data = data;
vcpu_args_set(params[0].vcpu, 1, test_data_page_vaddr);
vcpu_args_set(params[1].vcpu, 1, test_data_page_vaddr);
pipis_rcvd = (uint64_t *)addr_gva2hva(vm, (uint64_t)&ipis_rcvd);
params[0].pipis_rcvd = pipis_rcvd;
params[1].pipis_rcvd = pipis_rcvd;
/* Start halter vCPU thread and wait for it to execute first HLT. */
r = pthread_create(&threads[0], NULL, vcpu_thread, ¶ms[0]);
TEST_ASSERT(r == 0,
"pthread_create halter failed errno=%d", errno);
fprintf(stderr, "Halter vCPU thread started\n");
wait_secs = 0;
while ((wait_secs < max_halter_wait) && !data->hlt_count) {
sleep(1);
wait_secs++;
}
TEST_ASSERT(data->hlt_count,
"Halter vCPU did not execute first HLT within %d seconds",
max_halter_wait);
fprintf(stderr,
"Halter vCPU thread reported its APIC ID: %u after %d seconds.\n",
data->halter_apic_id, wait_secs);
r = pthread_create(&threads[1], NULL, vcpu_thread, ¶ms[1]);
TEST_ASSERT(r == 0, "pthread_create sender failed errno=%d", errno);
fprintf(stderr,
"IPI sender vCPU thread started. Letting vCPUs run for %d seconds.\n",
run_secs);
if (!migrate)
sleep(run_secs);
else
do_migrations(data, run_secs, delay_usecs, pipis_rcvd);
/*
* Cancel threads and wait for them to stop.
*/
cancel_join_vcpu_thread(threads[0], params[0].vcpu);
cancel_join_vcpu_thread(threads[1], params[1].vcpu);
fprintf(stderr,
"Test successful after running for %d seconds.\n"
"Sending vCPU sent %lu IPIs to halting vCPU\n"
"Halting vCPU halted %lu times, woke %lu times, received %lu IPIs.\n"
"Halter APIC ID=%#x\n"
"Sender ICR value=%#x ICR2 value=%#x\n"
"Halter TPR=%#x PPR=%#x LVR=%#x\n"
"Migrations attempted: %lu\n"
"Migrations completed: %lu\n",
run_secs, data->ipis_sent,
data->hlt_count, data->wake_count, *pipis_rcvd,
data->halter_apic_id,
data->icr, data->icr2,
data->halter_tpr, data->halter_ppr, data->halter_lvr,
data->migrations_attempted, data->migrations_completed);
kvm_vm_free(vm);
return 0;
}