The API is designed for userspace to first call prepare_{l2_stack,
hyp_state, eret_destination, nested_sync_handler}, with a function
supplied to prepare_eret_destination() to be run in L2. Then run_l2()
can be called in L1 to run the given function in L2.Signed-off-by: Wei-Lin Chang <[email protected]> --- tools/testing/selftests/kvm/Makefile.kvm | 2 + .../selftests/kvm/include/arm64/nested.h | 18 ++++++ .../testing/selftests/kvm/lib/arm64/nested.c | 61 +++++++++++++++++++ .../selftests/kvm/lib/arm64/nested_asm.S | 35 +++++++++++ 4 files changed, 116 insertions(+) create mode 100644 tools/testing/selftests/kvm/include/arm64/nested.h create mode 100644 tools/testing/selftests/kvm/lib/arm64/nested.c create mode 100644 tools/testing/selftests/kvm/lib/arm64/nested_asm.S diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm index 98da9fa4b8b7..5e681e8e0cd7 100644 --- a/tools/testing/selftests/kvm/Makefile.kvm +++ b/tools/testing/selftests/kvm/Makefile.kvm @@ -34,6 +34,8 @@ LIBKVM_arm64 += lib/arm64/gic.c LIBKVM_arm64 += lib/arm64/gic_v3.c LIBKVM_arm64 += lib/arm64/gic_v3_its.c LIBKVM_arm64 += lib/arm64/handlers.S +LIBKVM_arm64 += lib/arm64/nested.c +LIBKVM_arm64 += lib/arm64/nested_asm.S LIBKVM_arm64 += lib/arm64/processor.c LIBKVM_arm64 += lib/arm64/spinlock.c LIBKVM_arm64 += lib/arm64/ucall.c diff --git a/tools/testing/selftests/kvm/include/arm64/nested.h b/tools/testing/selftests/kvm/include/arm64/nested.h new file mode 100644 index 000000000000..739ff2ee0161 --- /dev/null +++ b/tools/testing/selftests/kvm/include/arm64/nested.h @@ -0,0 +1,18 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * ARM64 Nested virtualization defines + */ + +#ifndef SELFTEST_KVM_NESTED_H +#define SELFTEST_KVM_NESTED_H + +void prepare_l2_stack(struct kvm_vm *vm, struct kvm_vcpu *vcpu); +void prepare_hyp_state(struct kvm_vm *vm, struct kvm_vcpu *vcpu); +void prepare_eret_destination(struct kvm_vm *vm, struct kvm_vcpu *vcpu, void *l2_pc); +void prepare_nested_sync_handler(struct kvm_vm *vm, struct kvm_vcpu *vcpu); + +void run_l2(void); +void after_hvc(void); +void do_hvc(void); + +#endif /* SELFTEST_KVM_NESTED_H */ diff --git a/tools/testing/selftests/kvm/lib/arm64/nested.c b/tools/testing/selftests/kvm/lib/arm64/nested.c new file mode 100644 index 000000000000..111d02f44cfe --- /dev/null +++ b/tools/testing/selftests/kvm/lib/arm64/nested.c @@ -0,0 +1,61 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * ARM64 Nested virtualization helpers + */ + +#include "kvm_util.h" +#include "nested.h" +#include "processor.h" +#include "test_util.h" + +#include <asm/sysreg.h> + +static void hvc_handler(struct ex_regs *regs) +{ + GUEST_ASSERT_EQ(get_current_el(), 2); + GUEST_PRINTF("hvc handler\n"); + regs->pstate = PSR_MODE_EL2h | PSR_D_BIT | PSR_A_BIT | PSR_I_BIT | PSR_F_BIT; + regs->pc = (u64)after_hvc; +} + +void prepare_l2_stack(struct kvm_vm *vm, struct kvm_vcpu *vcpu) +{ + size_t l2_stack_size; + uint64_t l2_stack_paddr; + + l2_stack_size = vm->page_size == 4096 ? DEFAULT_STACK_PGS * vm->page_size : + vm->page_size; + l2_stack_paddr = __vm_phy_pages_alloc(vm, l2_stack_size / vm->page_size, + 0, 0, false); + vcpu_set_reg(vcpu, ARM64_CORE_REG(sp_el1), l2_stack_paddr + l2_stack_size); +} + +void prepare_hyp_state(struct kvm_vm *vm, struct kvm_vcpu *vcpu) +{ + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_HCR_EL2), HCR_EL2_RW); +} + +void prepare_eret_destination(struct kvm_vm *vm, struct kvm_vcpu *vcpu, void *l2_pc) +{ + vm_paddr_t do_hvc_paddr = addr_gva2gpa(vm, (vm_vaddr_t)do_hvc); + vm_paddr_t l2_pc_paddr = addr_gva2gpa(vm, (vm_vaddr_t)l2_pc); + + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_SPSR_EL2), PSR_MODE_EL1h | + PSR_D_BIT | + PSR_A_BIT | + PSR_I_BIT | + PSR_F_BIT); + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_ELR_EL2), l2_pc_paddr); + /* HACK: use TPIDR_EL2 to pass address, see run_l2() in nested_asm.S */ + vcpu_set_reg(vcpu, KVM_ARM64_SYS_REG(SYS_TPIDR_EL2), do_hvc_paddr); +} + +void prepare_nested_sync_handler(struct kvm_vm *vm, struct kvm_vcpu *vcpu) +{ + if (!vm->handlers) { + vm_init_descriptor_tables(vm); + vcpu_init_descriptor_tables(vcpu); + } + vm_install_sync_handler(vm, VECTOR_SYNC_LOWER_64, + ESR_ELx_EC_HVC64, hvc_handler); +} diff --git a/tools/testing/selftests/kvm/lib/arm64/nested_asm.S b/tools/testing/selftests/kvm/lib/arm64/nested_asm.S new file mode 100644 index 000000000000..4ecf2d510a6f --- /dev/null +++ b/tools/testing/selftests/kvm/lib/arm64/nested_asm.S @@ -0,0 +1,35 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * ARM64 Nested virtualization assembly helpers + */ + +.globl run_l2 +.globl after_hvc +.globl do_hvc +run_l2: + /* + * At this point TPIDR_EL2 will contain the gpa of do_hvc from + * prepare_eret_destination(). gpa of do_hvc have to be passed in + * because we want L2 to issue an hvc after it returns from the user + * passed function. In order for that to happen the lr must be + * controlled, which at this point holds the value of the address of + * the next instruction after this run_l2() call, which is not useful + * for L2. Additionally, L1 can't translate gva into gpa, so we can't + * calculate it here. + * + * So first save lr, then move TPIDR_EL2 to lr so when the user supplied + * L2 function returns, L2 jumps to do_hvc and let the L1 hvc handler + * take control. This implies we expect the L2 code to preserve lr and + * calls a regular ret in the end, which is true for normal C functions. + * The hvc handler will jump back to after_hvc when finished, and lr + * will be restored and we can return run_l2(). + */ + stp x29, lr, [sp, #-16]! + mrs x0, tpidr_el2 + mov lr, x0 + eret +after_hvc: + ldp x29, lr, [sp], #16 + ret +do_hvc: + hvc #0 -- 2.43.0
