[PATCH v6 6/6] KVM: arm64: selftests: Test for setting ID register from usersapce

[Jing Zhang]

Add a test to verify setting ID registers from userapce is handled
correctly by KVM.

Signed-off-by: Jing Zhang <jingzhangos at google.com>
---
 tools/testing/selftests/kvm/Makefile          |   1 +
 .../selftests/kvm/aarch64/set_id_regs.c       | 163 ++++++++++++++++++
 2 files changed, 164 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/aarch64/set_id_regs.c

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c692cc86e7da..87ceadc1292a 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -144,6 +144,7 @@ TEST_GEN_PROGS_aarch64 += aarch64/get-reg-list
 TEST_GEN_PROGS_aarch64 += aarch64/hypercalls
 TEST_GEN_PROGS_aarch64 += aarch64/page_fault_test
 TEST_GEN_PROGS_aarch64 += aarch64/psci_test
+TEST_GEN_PROGS_aarch64 += aarch64/set_id_regs
 TEST_GEN_PROGS_aarch64 += aarch64/smccc_filter
 TEST_GEN_PROGS_aarch64 += aarch64/vcpu_width_config
 TEST_GEN_PROGS_aarch64 += aarch64/vgic_init
diff --git a/tools/testing/selftests/kvm/aarch64/set_id_regs.c b/tools/testing/selftests/kvm/aarch64/set_id_regs.c
new file mode 100644
index 000000000000..e2242ef36bab
--- /dev/null
+++ b/tools/testing/selftests/kvm/aarch64/set_id_regs.c
@@ -0,0 +1,163 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * set_id_regs - Test for setting ID register from usersapce.
+ *
+ * Copyright (c) 2023 Google LLC.
+ *
+ *
+ * Test that KVM supports setting ID registers from userspace and handles the
+ * feature set correctly.
+ */
+
+#include <stdint.h>
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+#include <linux/bitfield.h>
+
+#define field_get(_mask, _reg) (((_reg) & (_mask)) >> (ffs(_mask) - 1))
+#define field_prep(_mask, _val) (((_val) << (ffs(_mask) - 1)) & (_mask))
+
+struct reg_feature {
+	uint64_t reg;
+	uint64_t ftr_mask;
+};
+
+static void guest_code(void)
+{
+	for (;;)
+		GUEST_SYNC(0);
+}
+
+static struct reg_feature lower_safe_reg_ftrs[] = {
+	{ KVM_ARM64_SYS_REG(SYS_ID_AA64DFR0_EL1), ARM64_FEATURE_MASK(ID_AA64DFR0_BRPS) },
+	{ KVM_ARM64_SYS_REG(SYS_ID_DFR0_EL1), ARM64_FEATURE_MASK(ID_DFR0_COPDBG) },
+	{ KVM_ARM64_SYS_REG(SYS_ID_AA64PFR0_EL1), ARM64_FEATURE_MASK(ID_AA64PFR0_EL3) },
+	{ KVM_ARM64_SYS_REG(SYS_ID_AA64MMFR0_EL1), ARM64_FEATURE_MASK(ID_AA64MMFR0_TGRAN4) },
+};
+
+static void test_user_set_lower_safe(struct kvm_vcpu *vcpu)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(lower_safe_reg_ftrs); i++) {
+		struct reg_feature *reg_ftr = lower_safe_reg_ftrs + i;
+		uint64_t val, new_val, ftr;
+
+		vcpu_get_reg(vcpu, reg_ftr->reg, &val);
+		ftr = field_get(reg_ftr->ftr_mask, val);
+
+		/* Set a safe value for the feature */
+		if (ftr > 0)
+			ftr--;
+
+		val &= ~reg_ftr->ftr_mask;
+		val |= field_prep(reg_ftr->ftr_mask, ftr);
+
+		vcpu_set_reg(vcpu, reg_ftr->reg, val);
+		vcpu_get_reg(vcpu, reg_ftr->reg, &new_val);
+		ASSERT_EQ(new_val, val);
+	}
+}
+
+static struct reg_feature exact_reg_ftrs[] = {
+	{ KVM_ARM64_SYS_REG(SYS_ID_AA64DFR0_EL1), ARM64_FEATURE_MASK(ID_AA64DFR0_DEBUGVER) },
+};
+
+static void test_user_set_exact(struct kvm_vcpu *vcpu)
+{
+	int i, r;
+
+	for (i = 0; i < ARRAY_SIZE(exact_reg_ftrs); i++) {
+		struct reg_feature *reg_ftr = exact_reg_ftrs + i;
+		uint64_t val, old_val, ftr;
+
+		vcpu_get_reg(vcpu, reg_ftr->reg, &val);
+		ftr = field_get(reg_ftr->ftr_mask, val);
+		old_val = val;
+
+		/* Exact match */
+		vcpu_set_reg(vcpu, reg_ftr->reg, val);
+		vcpu_get_reg(vcpu, reg_ftr->reg, &val);
+		ASSERT_EQ(val, old_val);
+
+		/* Smaller value */
+		if (ftr > 0)
+			ftr--;
+		val &= ~reg_ftr->ftr_mask;
+		val |= field_prep(reg_ftr->ftr_mask, ftr);
+		r = __vcpu_set_reg(vcpu, reg_ftr->reg, val);
+		TEST_ASSERT(r < 0 && errno == EINVAL,
+			    "Unexpected KVM_SET_ONE_REG error: r=%d, errno=%d", r, errno);
+		vcpu_get_reg(vcpu, reg_ftr->reg, &val);
+		ASSERT_EQ(val, old_val);
+
+		/* Bigger value */
+		ftr += 2;
+		val &= ~reg_ftr->ftr_mask;
+		val |= field_prep(reg_ftr->ftr_mask, ftr);
+		r = __vcpu_set_reg(vcpu, reg_ftr->reg, val);
+		TEST_ASSERT(r < 0 && errno == EINVAL,
+			    "Unexpected KVM_SET_ONE_REG error: r=%d, errno=%d", r, errno);
+		vcpu_get_reg(vcpu, reg_ftr->reg, &val);
+		ASSERT_EQ(val, old_val);
+	}
+}
+
+static struct reg_feature fail_reg_ftrs[] = {
+	{ KVM_ARM64_SYS_REG(SYS_ID_AA64DFR0_EL1), ARM64_FEATURE_MASK(ID_AA64DFR0_WRPS) },
+	{ KVM_ARM64_SYS_REG(SYS_ID_DFR0_EL1), ARM64_FEATURE_MASK(ID_DFR0_MPROFDBG) },
+	{ KVM_ARM64_SYS_REG(SYS_ID_AA64PFR0_EL1), ARM64_FEATURE_MASK(ID_AA64PFR0_EL2) },
+	{ KVM_ARM64_SYS_REG(SYS_ID_AA64MMFR0_EL1), ARM64_FEATURE_MASK(ID_AA64MMFR0_TGRAN64) },
+};
+
+static void test_user_set_fail(struct kvm_vcpu *vcpu)
+{
+	int i, r;
+
+	for (i = 0; i < ARRAY_SIZE(fail_reg_ftrs); i++) {
+		struct reg_feature *reg_ftr = fail_reg_ftrs + i;
+		uint64_t val, old_val, ftr;
+
+		vcpu_get_reg(vcpu, reg_ftr->reg, &val);
+		ftr = field_get(reg_ftr->ftr_mask, val);
+
+		/* Set a invalid value (too big) for the feature */
+		ftr++;
+
+		old_val = val;
+		val &= ~reg_ftr->ftr_mask;
+		val |= field_prep(reg_ftr->ftr_mask, ftr);
+
+		r = __vcpu_set_reg(vcpu, reg_ftr->reg, val);
+		TEST_ASSERT(r < 0 && errno == EINVAL,
+			    "Unexpected KVM_SET_ONE_REG error: r=%d, errno=%d", r, errno);
+
+		vcpu_get_reg(vcpu, reg_ftr->reg, &val);
+		ASSERT_EQ(val, old_val);
+	}
+}
+
+int main(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+
+	ksft_print_header();
+	ksft_set_plan(3);
+
+	test_user_set_lower_safe(vcpu);
+	ksft_test_result_pass("test_user_set_lower_safe\n");
+
+	test_user_set_exact(vcpu);
+	ksft_test_result_pass("test_user_set_exact\n");
+
+	test_user_set_fail(vcpu);
+	ksft_test_result_pass("test_user_set_fail\n");
+
+	kvm_vm_free(vm);
+
+	ksft_finished();
+}
-- 
2.41.0.255.g8b1d071c50-goog