[RFC PATCH 12/13] KVM: arm64: selftests: Add support for stress testing direct-injected vLPIs
Maximilian Dittgen
mdittgen at amazon.de
Thu Nov 20 06:03:01 PST 2025
vgic_lpi_stress stress tests LPIs by injecting MSIs to a guest's GIC.
Since these MSIs are purely defined in userspace, they are handled as
LPIs by the hypervisor as software interrupts.
We provide two ways to stress test direct-injected vLPIs.
- When per-vCPU vLPI injection is disabled, use -D flag to upgrade
all LPIs fired by the stress test to vLPIs. This flag mocks a
host_irq for each MSI and calls KVM_DEBUG_GIC_MSI_SETUP to create
and map vITS data structures needed for direct injection.
- When per-vCPU vLPI injection is enabled, use -s flag to pass
per-vCPU command strings to control the state of vPE initialization
on each vCPU throughout the test. Allows stress testing vLPI
injection on partially-enabled VMs.
Signed-off-by: Maximilian Dittgen <mdittgen at amazon.de>
---
.../selftests/kvm/arm64/vgic_lpi_stress.c | 181 +++++++++++++++++-
1 file changed, 177 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/kvm/arm64/vgic_lpi_stress.c b/tools/testing/selftests/kvm/arm64/vgic_lpi_stress.c
index e857a605f577..b3fe5fdf4285 100644
--- a/tools/testing/selftests/kvm/arm64/vgic_lpi_stress.c
+++ b/tools/testing/selftests/kvm/arm64/vgic_lpi_stress.c
@@ -18,9 +18,17 @@
#include "ucall.h"
#include "vgic.h"
+#define KVM_DEBUG_GIC_MSI_SETUP _IOW(KVMIO, 0xf3, struct kvm_debug_gic_msi_setup)
+
#define TEST_MEMSLOT_INDEX 1
#define GIC_LPI_OFFSET 8192
+#define SPI_IRQ_RANGE_OFFSET 32
+
+static bool vlpi_enabled;
+static bool string_mode;
+static char **vcpu_strings;
+static bool *vcpu_enabled;
static size_t nr_iterations = 1000;
static vm_paddr_t gpa_base;
@@ -222,6 +230,79 @@ static void setup_gic(void)
its_fd = vgic_its_setup(vm);
}
+static int enable_msi_vlpi_injection(u32 device_id, u32 event_id,
+ u32 vcpu_id, u32 vintid, u32 host_irq)
+{
+ struct kvm_debug_gic_msi_setup params = {
+ .device_id = device_id,
+ .event_id = event_id,
+ .vcpu_id = vcpu_id,
+ .vintid = vintid,
+ .host_irq = host_irq,
+ .itt_addr = test_data.itt_tables + (device_id * SZ_64K)
+ };
+
+ return __vm_ioctl(vm, KVM_DEBUG_GIC_MSI_SETUP, ¶ms);
+}
+
+static void upgrade_vcpu_lpis(struct kvm_vcpu *vcpu)
+{
+ u32 intid = GIC_LPI_OFFSET;
+ u32 target_vcpu = 0; /* Start round-robin from vCPU 0 */
+ u32 device_id, event_id;
+
+ for (device_id = 0; device_id < test_data.nr_devices; device_id++) {
+ for (event_id = 0; event_id < test_data.nr_event_ids;
+ event_id++) {
+ /*
+ * Only setup vLPI mapping if this is the target vCPU
+ * for this interrupt
+ */
+ if (target_vcpu == vcpu->id) {
+ /*
+ * we mock host_irqs in the SPI interrupt range
+ * of 100-1020 since selftest guests have no
+ * hardware devices
+ */
+ int ret = enable_msi_vlpi_injection(device_id,
+ event_id, vcpu->id, intid,
+ intid - GIC_LPI_OFFSET + SPI_IRQ_RANGE_OFFSET);
+
+ if (ret == -ENXIO || ret == -1) {
+ pr_info("Direct vLPI injection is disabled for vCPU %d, defaulting to software LPI handling\n",
+ vcpu->id);
+ return;
+ }
+ TEST_ASSERT(ret == 0,
+ "KVM_DEBUG_GIC_MSI_SETUP failed: %d\n",
+ ret);
+ }
+
+ intid++;
+ target_vcpu = (target_vcpu + 1) % test_data.nr_cpus;
+ }
+ }
+}
+
+
+
+static void enable_vcpu_vlpi_injection(int vcpu_id)
+{
+ int ret = ioctl(vm->fd, KVM_ENABLE_VCPU_VLPI, &vcpu_id);
+
+ TEST_ASSERT(ret == 0, "KVM_ENABLE_VCPU_VLPI failed: %d", ret);
+ pr_info("Enabled vLPI injection on vCPU %d\n", vcpu_id);
+ upgrade_vcpu_lpis(vcpus[vcpu_id]);
+}
+
+static void disable_vcpu_vlpi_injection(int vcpu_id)
+{
+ int ret = ioctl(vm->fd, KVM_DISABLE_VCPU_VLPI, &vcpu_id);
+
+ TEST_ASSERT(ret == 0, "KVM_DISABLE_VCPU_VLPI failed: %d", ret);
+ pr_info("Disabled vLPI injection on vCPU %d\n", vcpu_id);
+}
+
static void signal_lpi(u32 device_id, u32 event_id)
{
vm_paddr_t db_addr = GITS_BASE_GPA + GITS_TRANSLATER;
@@ -243,18 +324,36 @@ static void signal_lpi(u32 device_id, u32 event_id)
}
static pthread_barrier_t test_setup_barrier;
+static pthread_barrier_t vlpi_upgrade_barrier;
static void *lpi_worker_thread(void *data)
{
u32 device_id = (size_t)data;
u32 event_id;
size_t i;
+ int vcpu_id;
pthread_barrier_wait(&test_setup_barrier);
-
- for (i = 0; i < nr_iterations; i++)
+ pthread_barrier_wait(&vlpi_upgrade_barrier);
+
+ for (i = 0; i < nr_iterations; i++) {
+ /* conduct per-vCPU vLPI enablement/disablement */
+ if (string_mode) {
+ for (vcpu_id = 0; vcpu_id < test_data.nr_cpus; vcpu_id++) {
+ char action = vcpu_strings[vcpu_id][i];
+
+ if (action == 'e' && !vcpu_enabled[vcpu_id]) {
+ enable_vcpu_vlpi_injection(vcpu_id);
+ vcpu_enabled[vcpu_id] = true;
+ } else if (action == 'd' && vcpu_enabled[vcpu_id]) {
+ disable_vcpu_vlpi_injection(vcpu_id);
+ vcpu_enabled[vcpu_id] = false;
+ }
+ }
+ }
for (event_id = 0; event_id < test_data.nr_event_ids; event_id++)
signal_lpi(device_id, event_id);
+ }
return NULL;
}
@@ -270,6 +369,10 @@ static void *vcpu_worker_thread(void *data)
switch (get_ucall(vcpu, &uc)) {
case UCALL_SYNC:
pthread_barrier_wait(&test_setup_barrier);
+ /* if flag is set, set direct injection mappings for MSIs */
+ if (vlpi_enabled)
+ upgrade_vcpu_lpis(vcpu);
+ pthread_barrier_wait(&vlpi_upgrade_barrier);
continue;
case UCALL_DONE:
return NULL;
@@ -309,6 +412,7 @@ static void run_test(void)
TEST_ASSERT(lpi_threads && vcpu_threads, "Failed to allocate pthread arrays");
pthread_barrier_init(&test_setup_barrier, NULL, nr_vcpus + nr_devices + 1);
+ pthread_barrier_init(&vlpi_upgrade_barrier, NULL, nr_vcpus + nr_devices + 1);
for (i = 0; i < nr_vcpus; i++)
pthread_create(&vcpu_threads[i], NULL, vcpu_worker_thread, vcpus[i]);
@@ -317,6 +421,7 @@ static void run_test(void)
pthread_create(&lpi_threads[i], NULL, lpi_worker_thread, (void *)i);
pthread_barrier_wait(&test_setup_barrier);
+ pthread_barrier_wait(&vlpi_upgrade_barrier); /* Wait for all vLPI upgrades */
clock_gettime(CLOCK_MONOTONIC, &start);
@@ -361,13 +466,71 @@ static void destroy_vm(void)
free(vcpus);
}
+static int parse_vcpu_strings(const char *str)
+{
+ char *token, *saveptr, *str_copy;
+ int count = 0, len = -1, i;
+
+ str_copy = strdup(str);
+ TEST_ASSERT(str_copy, "Failed to allocate string copy");
+
+ token = strtok_r(str_copy, ",", &saveptr);
+ while (token) {
+ count++;
+ token = strtok_r(NULL, ",", &saveptr);
+ }
+ free(str_copy);
+
+ vcpu_strings = malloc(count * sizeof(char *));
+ vcpu_enabled = calloc(count, sizeof(bool));
+ TEST_ASSERT(vcpu_strings && vcpu_enabled, "Failed to allocate arrays");
+
+ str_copy = strdup(str);
+ token = strtok_r(str_copy, ",", &saveptr);
+ for (i = 0; i < count; i++) {
+ int token_len = strlen(token);
+
+ if (len == -1)
+ len = token_len;
+ else if (len != token_len)
+ TEST_FAIL("All strings must have same length");
+
+ TEST_ASSERT(len > 0, "Strings cannot be empty");
+
+ for (int j = 0; j < token_len; j++)
+ if (token[j] != 'd' && token[j] != 'e')
+ TEST_FAIL("Strings can only contain 'd' and 'e'");
+
+ vcpu_strings[i] = strdup(token);
+ TEST_ASSERT(vcpu_strings[i], "Failed to allocate string");
+ token = strtok_r(NULL, ",", &saveptr);
+ }
+ free(str_copy);
+
+ test_data.nr_cpus = count;
+ test_data.nr_devices = 1;
+ test_data.nr_event_ids = count;
+ nr_iterations = len;
+
+ return 0;
+}
+
static void pr_usage(const char *name)
{
- pr_info("%s [-v NR_VCPUS] [-d NR_DEVICES] [-e NR_EVENTS] [-i ITERS] -h\n", name);
+ pr_info("%s -D [-v NR_VCPUS] [-d NR_DEVICES] [-e NR_EVENTS] [-i ITERS] | -s STRINGS -h\n",
+ name);
+ pr_info(" -D:\tenable direct vLPI injection (default: %s)\n",
+ vlpi_enabled ? "true" : "false");
pr_info(" -v:\tnumber of vCPUs (default: %u)\n", test_data.nr_cpus);
pr_info(" -d:\tnumber of devices (default: %u)\n", test_data.nr_devices);
pr_info(" -e:\tnumber of event IDs per device (default: %u)\n", test_data.nr_event_ids);
pr_info(" -i:\tnumber of iterations (default: %lu)\n", nr_iterations);
+ pr_info(" -s:\tvCPU control strings (comma-separated, e.g., \"dede,eede\"),\n");
+ pr_info(" \twhere each string corresponds to the per-iteration vLPI status\n");
+ pr_info(" \tof a single vCPU. \"ddeed\" means a vCPU will be vLPI-disabled for two\n");
+ pr_info(" \titerations, enabled for two iterations, then disabled for one iteration.\n");
+ pr_info(" \tNumber of strings corresponds to the number of vCPUs, and all strings must\n");
+ pr_info(" \tbe of the same size. Cannot be used in conjunction with other flags.\n");
}
int main(int argc, char **argv)
@@ -377,8 +540,11 @@ int main(int argc, char **argv)
TEST_REQUIRE(kvm_supports_vgic_v3());
- while ((c = getopt(argc, argv, "hv:d:e:i:")) != -1) {
+ while ((c = getopt(argc, argv, "hDv:d:e:i:s:")) != -1) {
switch (c) {
+ case 'D':
+ vlpi_enabled = true;
+ break;
case 'v':
test_data.nr_cpus = atoi(optarg);
break;
@@ -391,6 +557,10 @@ int main(int argc, char **argv)
case 'i':
nr_iterations = strtoul(optarg, NULL, 0);
break;
+ case 's':
+ string_mode = true;
+ parse_vcpu_strings(optarg);
+ break;
case 'h':
default:
pr_usage(argv[0]);
@@ -398,6 +568,9 @@ int main(int argc, char **argv)
}
}
+ if (string_mode && argc > 3)
+ TEST_FAIL("-s cannot be used with other flags");
+
nr_threads = test_data.nr_cpus + test_data.nr_devices;
if (nr_threads > get_nprocs())
pr_info("WARNING: running %u threads on %d CPUs; performance is degraded.\n",
--
2.50.1 (Apple Git-155)
Amazon Web Services Development Center Germany GmbH
Tamara-Danz-Str. 13
10243 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Christof Hellmis
Eingetragen am Amtsgericht Charlottenburg unter HRB 257764 B
Sitz: Berlin
Ust-ID: DE 365 538 597
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