1 files changed, 121 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/aarch64/psci_cpu_on_test.c b/tools/testing/selftests/kvm/aarch64/psci_cpu_on_test.c
new file mode 100644
index 000000000000..018c269990e1
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/psci_cpu_on_test.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * psci_cpu_on_test - Test that the observable state of a vCPU targeted by the
+ * CPU_ON PSCI call matches what the caller requested.
+ *
+ * Copyright (c) 2021 Google LLC.
+ *
+ * This is a regression test for a race between KVM servicing the PSCI call and
+ * userspace reading the vCPUs registers.
+ */
+
+#define _GNU_SOURCE
+
+#include <linux/psci.h>
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+#define VCPU_ID_SOURCE 0
+#define VCPU_ID_TARGET 1
+
+#define CPU_ON_ENTRY_ADDR 0xfeedf00dul
+#define CPU_ON_CONTEXT_ID 0xdeadc0deul
+
+static uint64_t psci_cpu_on(uint64_t target_cpu, uint64_t entry_addr,
+			    uint64_t context_id)
+{
+	register uint64_t x0 asm("x0") = PSCI_0_2_FN64_CPU_ON;
+	register uint64_t x1 asm("x1") = target_cpu;
+	register uint64_t x2 asm("x2") = entry_addr;
+	register uint64_t x3 asm("x3") = context_id;
+
+	asm("hvc #0"
+	    : "=r"(x0)
+	    : "r"(x0), "r"(x1), "r"(x2), "r"(x3)
+	    : "memory");
+
+	return x0;
+}
+
+static uint64_t psci_affinity_info(uint64_t target_affinity,
+				   uint64_t lowest_affinity_level)
+{
+	register uint64_t x0 asm("x0") = PSCI_0_2_FN64_AFFINITY_INFO;
+	register uint64_t x1 asm("x1") = target_affinity;
+	register uint64_t x2 asm("x2") = lowest_affinity_level;
+
+	asm("hvc #0"
+	    : "=r"(x0)
+	    : "r"(x0), "r"(x1), "r"(x2)
+	    : "memory");
+
+	return x0;
+}
+
+static void guest_main(uint64_t target_cpu)
+{
+	GUEST_ASSERT(!psci_cpu_on(target_cpu, CPU_ON_ENTRY_ADDR, CPU_ON_CONTEXT_ID));
+	uint64_t target_state;
+
+	do {
+		target_state = psci_affinity_info(target_cpu, 0);
+
+		GUEST_ASSERT((target_state == PSCI_0_2_AFFINITY_LEVEL_ON) ||
+			     (target_state == PSCI_0_2_AFFINITY_LEVEL_OFF));
+	} while (target_state != PSCI_0_2_AFFINITY_LEVEL_ON);
+
+	GUEST_DONE();
+}
+
+int main(void)
+{
+	uint64_t target_mpidr, obs_pc, obs_x0;
+	struct kvm_vcpu_init init;
+	struct kvm_vm *vm;
+	struct ucall uc;
+
+	vm = vm_create(VM_MODE_DEFAULT, DEFAULT_GUEST_PHY_PAGES, O_RDWR);
+	kvm_vm_elf_load(vm, program_invocation_name);
+	ucall_init(vm, NULL);
+
+	vm_ioctl(vm, KVM_ARM_PREFERRED_TARGET, &init);
+	init.features[0] |= (1 << KVM_ARM_VCPU_PSCI_0_2);
+
+	aarch64_vcpu_add_default(vm, VCPU_ID_SOURCE, &init, guest_main);
+
+	/*
+	 * make sure the target is already off when executing the test.
+	 */
+	init.features[0] |= (1 << KVM_ARM_VCPU_POWER_OFF);
+	aarch64_vcpu_add_default(vm, VCPU_ID_TARGET, &init, guest_main);
+
+	get_reg(vm, VCPU_ID_TARGET, ARM64_SYS_REG(MPIDR_EL1), &target_mpidr);
+	vcpu_args_set(vm, VCPU_ID_SOURCE, 1, target_mpidr & MPIDR_HWID_BITMASK);
+	vcpu_run(vm, VCPU_ID_SOURCE);
+
+	switch (get_ucall(vm, VCPU_ID_SOURCE, &uc)) {
+	case UCALL_DONE:
+		break;
+	case UCALL_ABORT:
+		TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0], __FILE__,
+			  uc.args[1]);
+		break;
+	default:
+		TEST_FAIL("Unhandled ucall: %lu", uc.cmd);
+	}
+
+	get_reg(vm, VCPU_ID_TARGET, ARM64_CORE_REG(regs.pc), &obs_pc);
+	get_reg(vm, VCPU_ID_TARGET, ARM64_CORE_REG(regs.regs[0]), &obs_x0);
+
+	TEST_ASSERT(obs_pc == CPU_ON_ENTRY_ADDR,
+		    "unexpected target cpu pc: %lx (expected: %lx)",
+		    obs_pc, CPU_ON_ENTRY_ADDR);
+	TEST_ASSERT(obs_x0 == CPU_ON_CONTEXT_ID,
+		    "unexpected target context id: %lx (expected: %lx)",
+		    obs_x0, CPU_ON_CONTEXT_ID);
+
+	kvm_vm_free(vm);
+	return 0;
+}