On Sun, Apr 12, 2026 at 03:22:15PM +0100, Wei-Lin Chang wrote: > This selftest simply starts an L1, which starts its own guest (L2). L2 > runs without stage-1 and 2 translations, it calls an HVC to jump back > to L1.
How do you disable both the nested guest (L2)'s MMU and stage 2 translations? Itaru. > > Signed-off-by: Wei-Lin Chang <[email protected]> > --- > tools/testing/selftests/kvm/Makefile.kvm | 1 + > .../selftests/kvm/arm64/hello_nested.c | 103 ++++++++++++++++++ > 2 files changed, 104 insertions(+) > create mode 100644 tools/testing/selftests/kvm/arm64/hello_nested.c > > diff --git a/tools/testing/selftests/kvm/Makefile.kvm > b/tools/testing/selftests/kvm/Makefile.kvm > index 3dc3e39f7025..e8c108e0c487 100644 > --- a/tools/testing/selftests/kvm/Makefile.kvm > +++ b/tools/testing/selftests/kvm/Makefile.kvm > @@ -168,6 +168,7 @@ TEST_GEN_PROGS_arm64 += arm64/arch_timer_edge_cases > TEST_GEN_PROGS_arm64 += arm64/at > TEST_GEN_PROGS_arm64 += arm64/debug-exceptions > TEST_GEN_PROGS_arm64 += arm64/hello_el2 > +TEST_GEN_PROGS_arm64 += arm64/hello_nested > TEST_GEN_PROGS_arm64 += arm64/host_sve > TEST_GEN_PROGS_arm64 += arm64/hypercalls > TEST_GEN_PROGS_arm64 += arm64/external_aborts > diff --git a/tools/testing/selftests/kvm/arm64/hello_nested.c > b/tools/testing/selftests/kvm/arm64/hello_nested.c > new file mode 100644 > index 000000000000..97387e4697b3 > --- /dev/null > +++ b/tools/testing/selftests/kvm/arm64/hello_nested.c > @@ -0,0 +1,103 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * hello_nested - Go from vEL2 to EL1 then back > + */ > + > +#include "nested.h" > +#include "processor.h" > +#include "test_util.h" > +#include "ucall.h" > + > +#define XLATE2GPA (0xABCD) > +#define L2STACKSZ (0x100) > + > +/* > + * TPIDR_EL2 is used to store vcpu id, so save and restore it. > + */ > +static vm_paddr_t ucall_translate_to_gpa(void *gva) > +{ > + vm_paddr_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(); > +} > + > +static void guest_code(void) > +{ > + struct vcpu vcpu; > + struct hyp_data hyp_data; > + int ret; > + vm_paddr_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(); > + > + ret = run_l2(&vcpu, &hyp_data); > + GUEST_ASSERT_EQ(ret, ARM_EXCEPTION_TRAP); > + GUEST_DONE(); > +} > + > +int main(void) > +{ > + struct kvm_vcpu_init init; > + struct kvm_vcpu *vcpu; > + struct kvm_vm *vm; > + struct ucall uc; > + vm_paddr_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, (vm_vaddr_t)uc.args[1]); > + vcpu_set_reg(vcpu, > KVM_ARM64_SYS_REG(SYS_TPIDR_EL2), gpa); > + } > + break; > + case UCALL_PRINTF: > + pr_info("%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 >
