The shadow_stage2 test is aimed to exercise the shadow page table
management code in KVM. In this first patch a basic test similar to
hello_nested is created. Right now it doesn't turn on stage-2 for the
nested guest (L2) yet, therefore the shadow page table code in KVM will
only be triggered minimally now.

Signed-off-by: Wei-Lin Chang <[email protected]>
---
 tools/testing/selftests/kvm/Makefile.kvm      |   1 +
 .../selftests/kvm/arm64/shadow_stage2.c       | 128 ++++++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/arm64/shadow_stage2.c

diff --git a/tools/testing/selftests/kvm/Makefile.kvm 
b/tools/testing/selftests/kvm/Makefile.kvm
index e8c108e0c487..c0fac2ba1339 100644
--- a/tools/testing/selftests/kvm/Makefile.kvm
+++ b/tools/testing/selftests/kvm/Makefile.kvm
@@ -176,6 +176,7 @@ TEST_GEN_PROGS_arm64 += arm64/page_fault_test
 TEST_GEN_PROGS_arm64 += arm64/psci_test
 TEST_GEN_PROGS_arm64 += arm64/sea_to_user
 TEST_GEN_PROGS_arm64 += arm64/set_id_regs
+TEST_GEN_PROGS_arm64 += arm64/shadow_stage2
 TEST_GEN_PROGS_arm64 += arm64/smccc_filter
 TEST_GEN_PROGS_arm64 += arm64/vcpu_width_config
 TEST_GEN_PROGS_arm64 += arm64/vgic_init
diff --git a/tools/testing/selftests/kvm/arm64/shadow_stage2.c 
b/tools/testing/selftests/kvm/arm64/shadow_stage2.c
new file mode 100644
index 000000000000..cf76a2b0582d
--- /dev/null
+++ b/tools/testing/selftests/kvm/arm64/shadow_stage2.c
@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * shadow_stage2 - Test correctness of shadow stage 2
+ */
+
+#include "nested.h"
+#include "processor.h"
+#include "test_util.h"
+#include "ucall.h"
+
+#define XLATE2GPA      (0xABCD)
+#define L2STACKSZ      (0x100)
+
+#define L2SUCCESS      (0x0)
+#define L2FAILED       (0x1)
+#define L2SYNC         (0x2)
+
+/*
+ * TPIDR_EL2 is used to store vcpu id, so save and restore it.
+ */
+static gpa_t ucall_translate_to_gpa(void *gva)
+{
+       gpa_t gpa;
+       u64 vcpu_id = read_sysreg(tpidr_el2);
+
+       GUEST_SYNC2(XLATE2GPA, gva);
+
+       /* get the result from userspace */
+       gpa = read_sysreg(tpidr_el2);
+
+       write_sysreg(vcpu_id, tpidr_el2);
+
+       return gpa;
+}
+
+static void l2_guest_code(void)
+{
+       do_hvc(L2SYNC, 10, 0);
+       do_hvc(L2SYNC, 20, 0);
+       do_hvc(L2SYNC, 30, 0);
+
+       do_hvc(L2SUCCESS, 0, 0);
+}
+
+static void guest_code(void)
+{
+       struct vcpu vcpu;
+       struct hyp_data hyp_data;
+       int ret, i = 0;
+       gpa_t l2_pc, l2_stack_top;
+       /* force 16-byte alignment for the stack pointer */
+       u8 l2_stack[L2STACKSZ] __attribute__((aligned(16)));
+
+       GUEST_ASSERT_EQ(get_current_el(), 2);
+       GUEST_PRINTF("vEL2 entry\n");
+
+       l2_pc = ucall_translate_to_gpa(l2_guest_code);
+       l2_stack_top = ucall_translate_to_gpa(&l2_stack[L2STACKSZ]);
+
+       init_vcpu(&vcpu, l2_pc, l2_stack_top);
+       prepare_hyp();
+
+       while (true) {
+               GUEST_PRINTF("L2 enter\n");
+               ret = run_l2(&vcpu, &hyp_data);
+               GUEST_PRINTF("L2 exit\n");
+               GUEST_ASSERT_EQ(ret, ARM_EXCEPTION_TRAP);
+               GUEST_ASSERT_EQ(ESR_ELx_EC(read_sysreg(esr_el2)), 
ESR_ELx_EC_HVC64);
+
+               if (vcpu.context.regs.regs[0] == L2SYNC)
+                       GUEST_SYNC3(L2SYNC, i++, vcpu.context.regs.regs[1]);
+               else
+                       break;
+       }
+
+       if (vcpu.context.regs.regs[0] != L2SUCCESS)
+               GUEST_FAIL("L2 failed\n");
+
+       GUEST_PRINTF("L2 success!\n");
+       GUEST_DONE();
+}
+
+int main(void)
+{
+       struct kvm_vcpu_init init;
+       struct kvm_vcpu *vcpu;
+       struct kvm_vm *vm;
+       struct ucall uc;
+       gpa_t gpa;
+
+       TEST_REQUIRE(kvm_check_cap(KVM_CAP_ARM_EL2));
+       vm = vm_create(1);
+
+       kvm_get_default_vcpu_target(vm, &init);
+       init.features[0] |= BIT(KVM_ARM_VCPU_HAS_EL2);
+       vcpu = aarch64_vcpu_add(vm, 0, &init, guest_code);
+       kvm_arch_vm_finalize_vcpus(vm);
+
+       while (true) {
+               vcpu_run(vcpu);
+
+               switch (get_ucall(vcpu, &uc)) {
+               case UCALL_SYNC:
+                       if (uc.args[0] == XLATE2GPA) {
+                               gpa = addr_gva2gpa(vm, (gva_t)uc.args[1]);
+                               vcpu_set_reg(vcpu, 
KVM_ARM64_SYS_REG(SYS_TPIDR_EL2), gpa);
+                       }
+                       if (uc.args[0] == L2SYNC)
+                               pr_info("L2SYNC, L1 info: %ld, L2 info: %ld\n", 
uc.args[1], uc.args[2]);
+                       break;
+               case UCALL_PRINTF:
+                       pr_info("[L1] %s", uc.buffer);
+                       break;
+               case UCALL_DONE:
+                       pr_info("DONE!\n");
+                       goto end;
+               case UCALL_ABORT:
+                       REPORT_GUEST_ASSERT(uc);
+                       fallthrough;
+               default:
+                       TEST_FAIL("Unhandled ucall: %ld\n", uc.cmd);
+               }
+       }
+
+end:
+       kvm_vm_free(vm);
+       return 0;
+}
-- 
2.43.0


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