[kvm-unit-tests PATCH v3 12/27] x86: add IPI stress test

[Maxim Levitsky <mlevitsk@redhat.com>]

Adds a test that sends IPIs between vCPUs and detects missing IPIs

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 x86/Makefile.common |   3 +-
 x86/ipi_stress.c    | 167 ++++++++++++++++++++++++++++++++++++++++++++
 x86/unittests.cfg   |  10 +++
 3 files changed, 179 insertions(+), 1 deletion(-)
 create mode 100644 x86/ipi_stress.c

diff --git a/x86/Makefile.common b/x86/Makefile.common
index fa0a50e6..08cc036b 100644
--- a/x86/Makefile.common
+++ b/x86/Makefile.common
@@ -89,7 +89,8 @@ tests-common = $(TEST_DIR)/vmexit.$(exe) $(TEST_DIR)/tsc.$(exe) \
                $(TEST_DIR)/eventinj.$(exe) \
                $(TEST_DIR)/smap.$(exe) \
                $(TEST_DIR)/umip.$(exe) \
-               $(TEST_DIR)/smm_int_window.$(exe)
+               $(TEST_DIR)/smm_int_window.$(exe) \
+               $(TEST_DIR)/ipi_stress.$(exe)
 
 # The following test cases are disabled when building EFI tests because they
 # use absolute addresses in their inline assembly code, which cannot compile
diff --git a/x86/ipi_stress.c b/x86/ipi_stress.c
new file mode 100644
index 00000000..dea3e605
--- /dev/null
+++ b/x86/ipi_stress.c
@@ -0,0 +1,167 @@
+#include "libcflat.h"
+#include "smp.h"
+#include "alloc.h"
+#include "apic.h"
+#include "processor.h"
+#include "isr.h"
+#include "asm/barrier.h"
+#include "delay.h"
+#include "desc.h"
+#include "msr.h"
+#include "vm.h"
+#include "types.h"
+#include "alloc_page.h"
+#include "vmalloc.h"
+#include "random.h"
+
+u64 num_iterations = 100000;
+float hlt_prob = 0.1;
+volatile bool end_test;
+
+#define APIC_TIMER_PERIOD (1000*1000*1000)
+
+struct cpu_test_state {
+	volatile u64 isr_count;
+	u64 last_isr_count;
+	struct random_state random;
+	int smp_id;
+} *cpu_states;
+
+
+static void ipi_interrupt_handler(isr_regs_t *r)
+{
+	cpu_states[smp_id()].isr_count++;
+	eoi();
+}
+
+static void local_timer_interrupt(isr_regs_t *r)
+{
+	struct cpu_test_state *state = &cpu_states[smp_id()];
+
+	u64 isr_count = state->isr_count;
+	unsigned long diff =  isr_count - state->last_isr_count;
+
+	if (!diff) {
+		printf("\n");
+		printf("hang detected!!\n");
+		end_test = true;
+		goto out;
+	}
+
+	printf("made %ld IPIs\n", diff * cpu_count());
+	state->last_isr_count = state->isr_count;
+out:
+	eoi();
+}
+
+static void wait_for_ipi(struct cpu_test_state *state)
+{
+	u64 old_count = state->isr_count;
+	bool use_halt = random_decision(&state->random, hlt_prob);
+
+	do {
+		if (use_halt) {
+			safe_halt();
+			cli();
+		} else
+			sti_nop_cli();
+
+	} while (old_count == state->isr_count);
+
+	assert(state->isr_count == old_count + 1);
+}
+
+
+static void vcpu_init(void *)
+{
+	struct cpu_test_state *state = &cpu_states[smp_id()];
+
+	memset(state, 0, sizeof(*state));
+
+	/* To make it easier to see iteration number in the trace */
+	handle_irq(0x40, ipi_interrupt_handler);
+	handle_irq(0x50, ipi_interrupt_handler);
+
+	state->random = get_prng();
+	state->isr_count = 0;
+	state->smp_id = smp_id();
+}
+
+static void vcpu_code(void *)
+{
+	struct cpu_test_state *state = &cpu_states[smp_id()];
+	int ncpus = cpu_count();
+	u64 i;
+	u8 target_smp_id;
+
+	if (state->smp_id > 0)
+		wait_for_ipi(state);
+
+	target_smp_id = state->smp_id == ncpus - 1 ? 0 : state->smp_id  + 1;
+
+	for (i = 0; i < num_iterations && !end_test; i++) {
+		// send IPI to a next vCPU in a circular fashion
+		apic_icr_write(APIC_INT_ASSERT |
+				APIC_DEST_PHYSICAL |
+				APIC_DM_FIXED |
+				(i % 2 ? 0x40 : 0x50),
+				target_smp_id);
+
+		if (i == (num_iterations - 1) && state->smp_id > 0)
+			break;
+
+		// wait for the IPI interrupt chain to come back to us
+		wait_for_ipi(state);
+	}
+}
+
+int main(int argc, void **argv)
+{
+	int cpu, ncpus = cpu_count();
+
+	handle_irq(0xF0, local_timer_interrupt);
+	apic_setup_timer(0xF0, APIC_LVT_TIMER_PERIODIC);
+
+	if (argc > 1) {
+		int hlt_param = atol(argv[1]);
+
+		if (hlt_param == 1)
+			hlt_prob = 100;
+		else if (hlt_param == 0)
+			hlt_prob = 0;
+	}
+
+	if (argc > 2)
+		num_iterations = atol(argv[2]);
+
+	setup_vm();
+	init_prng();
+
+	cpu_states = calloc(ncpus, sizeof(cpu_states[0]));
+
+	printf("found %d cpus\n", ncpus);
+	printf("running for %lld iterations\n",
+		(unsigned long long)num_iterations);
+
+	on_cpus(vcpu_init, NULL);
+
+	apic_start_timer(1000*1000*1000);
+
+	printf("test started, waiting to end...\n");
+
+	on_cpus(vcpu_code, NULL);
+
+	apic_stop_timer();
+	apic_cleanup_timer();
+
+	for (cpu = 0; cpu < ncpus; ++cpu) {
+		u64 result = cpu_states[cpu].isr_count;
+
+		report(result == num_iterations,
+				"Number of IPIs match (%lld)",
+				(unsigned long long)result);
+	}
+
+	free((void *)cpu_states);
+	return report_summary();
+}
diff --git a/x86/unittests.cfg b/x86/unittests.cfg
index df248dff..b0fd92fb 100644
--- a/x86/unittests.cfg
+++ b/x86/unittests.cfg
@@ -74,6 +74,16 @@ smp = 2
 file = smptest.flat
 smp = 3
 
+[ipi_stress]
+file = ipi_stress.flat
+extra_params = -cpu host,-x2apic -global kvm-pit.lost_tick_policy=discard -machine kernel-irqchip=on
+smp = 4
+
+[ipi_stress_x2apic]
+file = ipi_stress.flat
+extra_params = -cpu host,+x2apic -global kvm-pit.lost_tick_policy=discard -machine kernel-irqchip=on
+smp = 4
+
 [vmexit_cpuid]
 file = vmexit.flat
 extra_params = -append 'cpuid'
-- 
2.34.3