[PATCH 2/2] KVM: arm64: selftests: Add tests for MMIO external abort injection

[Oliver Upton <oliver.upton@linux.dev>]

Test that the plumbing exposed to userspace for injecting aborts in
response to unexpected MMIO works as intended in two different flavors:

 - A 'normal' MMIO instruction (i.e. ESR_ELx.ISV=1)

 - An ISV=0 MMIO instruction with/without KVM_CAP_ARM_NISV_TO_USER
   enabled

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../selftests/kvm/aarch64/mmio_abort.c        | 158 ++++++++++++++++++
 2 files changed, 159 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/aarch64/mmio_abort.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 960cf6a77198..98957a99ead6 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -156,6 +156,7 @@ TEST_GEN_PROGS_aarch64 += aarch64/aarch32_id_regs
 TEST_GEN_PROGS_aarch64 += aarch64/arch_timer_edge_cases
 TEST_GEN_PROGS_aarch64 += aarch64/debug-exceptions
 TEST_GEN_PROGS_aarch64 += aarch64/hypercalls
+TEST_GEN_PROGS_aarch64 += aarch64/mmio_abort
 TEST_GEN_PROGS_aarch64 += aarch64/page_fault_test
 TEST_GEN_PROGS_aarch64 += aarch64/psci_test
 TEST_GEN_PROGS_aarch64 += aarch64/set_id_regs
diff --git a/tools/testing/selftests/kvm/aarch64/mmio_abort.c b/tools/testing/selftests/kvm/aarch64/mmio_abort.c
new file mode 100644
index 000000000000..08c4afec1f28
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/mmio_abort.c
@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * mmio_abort - Tests for userspace MMIO abort injection
+ *
+ * Copyright (c) 2024 Google LLC
+ */
+#include "processor.h"
+#include "test_util.h"
+
+#define MMIO_ADDR	0x8000000ULL
+
+#define ESR_ELx_FSC_EXTABT	(0x10)
+
+static u64 expected_abort_pc;
+
+static void expect_sea_handler(struct ex_regs *regs)
+{
+	GUEST_ASSERT_EQ(regs->pc, expected_abort_pc);
+	GUEST_ASSERT(read_sysreg(esr_el1) & ESR_ELx_FSC_EXTABT);
+
+	GUEST_DONE();
+}
+
+static void unexpected_dabt_handler(struct ex_regs *regs)
+{
+	GUEST_FAIL("Unexpected data abort at PC: %lx\n", regs->pc);
+}
+
+static struct kvm_vm *vm_create_with_dabt_handler(struct kvm_vcpu **vcpu, void *guest_code,
+						  handler_fn dabt_handler)
+{
+	struct kvm_vm *vm = vm_create_with_one_vcpu(vcpu, guest_code);
+
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(*vcpu);
+	vm_install_sync_handler(vm, VECTOR_SYNC_CURRENT, ESR_EC_DABT, dabt_handler);
+
+	virt_map(vm, MMIO_ADDR, MMIO_ADDR, 1);
+
+	return vm;
+}
+
+static void vcpu_inject_extabt(struct kvm_vcpu *vcpu)
+{
+	struct kvm_vcpu_events events = {};
+
+	events.exception.ext_dabt_pending = true;
+	vcpu_events_set(vcpu, &events);
+}
+
+static void vcpu_run_expect_done(struct kvm_vcpu *vcpu)
+{
+	struct ucall uc;
+
+	vcpu_run(vcpu);
+	switch (get_ucall(vcpu, &uc)) {
+	case UCALL_ABORT:
+		REPORT_GUEST_ASSERT(uc);
+		break;
+	case UCALL_DONE:
+		break;
+	default:
+		TEST_FAIL("Unexpected ucall: %lu", uc.cmd);
+	}
+}
+
+extern char test_mmio_abort_insn;
+
+static void test_mmio_abort_guest(void)
+{
+	WRITE_ONCE(expected_abort_pc, (u64)&test_mmio_abort_insn);
+
+	asm volatile("test_mmio_abort_insn:\n\t"
+		     "ldr x0, [%0]\n\t"
+		     : : "r" (MMIO_ADDR) : "x0", "memory");
+
+	GUEST_FAIL("MMIO instruction should not retire");
+}
+
+/*
+ * Test that KVM doesn't complete MMIO emulation when userspace has made an
+ * external abort pending for the instruction.
+ */
+static void test_mmio_abort(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = vm_create_with_dabt_handler(&vcpu, test_mmio_abort_guest,
+							expect_sea_handler);
+	struct kvm_run *run = vcpu->run;
+
+	vcpu_run(vcpu);
+	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_MMIO);
+	TEST_ASSERT_EQ(run->mmio.phys_addr, MMIO_ADDR);
+	TEST_ASSERT_EQ(run->mmio.len, sizeof(unsigned long));
+	TEST_ASSERT(!run->mmio.is_write, "Expected MMIO read");
+
+	vcpu_inject_extabt(vcpu);
+	vcpu_run_expect_done(vcpu);
+	kvm_vm_free(vm);
+}
+
+extern char test_mmio_nisv_insn;
+
+static void test_mmio_nisv_guest(void)
+{
+	WRITE_ONCE(expected_abort_pc, (u64)&test_mmio_nisv_insn);
+
+	asm volatile("test_mmio_nisv_insn:\n\t"
+		     "ldr x0, [%0], #8\n\t"
+		     : : "r" (MMIO_ADDR) : "x0", "memory");
+
+	GUEST_FAIL("MMIO instruction should not retire");
+}
+
+/*
+ * Test that the KVM_RUN ioctl fails for ESR_EL2.ISV=0 MMIO aborts if userspace
+ * hasn't enabled KVM_CAP_ARM_NISV_TO_USER.
+ */
+static void test_mmio_nisv(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = vm_create_with_dabt_handler(&vcpu, test_mmio_nisv_guest,
+							unexpected_dabt_handler);
+
+	TEST_ASSERT(_vcpu_run(vcpu), "Expected nonzero return code from KVM_RUN");
+	TEST_ASSERT_EQ(errno, ENOSYS);
+
+	kvm_vm_free(vm);
+}
+
+/*
+ * Test that ESR_EL2.ISV=0 MMIO aborts reach userspace and that an injected SEA
+ * reaches the guest.
+ */
+static void test_mmio_nisv_abort(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm = vm_create_with_dabt_handler(&vcpu, test_mmio_nisv_guest,
+							expect_sea_handler);
+	struct kvm_run *run = vcpu->run;
+
+	vm_enable_cap(vm, KVM_CAP_ARM_NISV_TO_USER, 1);
+
+	vcpu_run(vcpu);
+	TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_ARM_NISV);
+	TEST_ASSERT_EQ(run->arm_nisv.fault_ipa, MMIO_ADDR);
+
+	vcpu_inject_extabt(vcpu);
+	vcpu_run_expect_done(vcpu);
+	kvm_vm_free(vm);
+}
+
+int main(void)
+{
+	test_mmio_abort();
+	test_mmio_nisv();
+	test_mmio_nisv_abort();
+}
-- 
2.47.0.rc1.288.g06298d1525-goog