From 97a71a5455997d72adfd74e9d575d782d7c2ab9a Mon Sep 17 00:00:00 2001 From: Jim Mattson Date: Mon, 26 Oct 2020 11:09:22 -0700 Subject: [PATCH] KVM: selftests: test behavior of unmapped L2 APIC-access address Add a regression test for commit 671ddc700fd0 ("KVM: nVMX: Don't leak L1 MMIO regions to L2"). First, check to see that an L2 guest can be launched with a valid APIC-access address that is backed by a page of L1 physical memory. Next, set the APIC-access address to a (valid) L1 physical address that is not backed by memory. KVM can't handle this situation, so resuming L2 should result in a KVM exit for internal error (emulation). Signed-off-by: Jim Mattson Reviewed-by: Ricardo Koller Reviewed-by: Peter Shier Message-Id: <20201026180922.3120555-1-jmattson@google.com> Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/include/x86_64/vmx.h | 6 + tools/testing/selftests/kvm/lib/x86_64/vmx.c | 9 ++ .../kvm/x86_64/vmx_apic_access_test.c | 142 ++++++++++++++++++ 5 files changed, 159 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index 307ceaadbbb9..d2c2d6205008 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -15,6 +15,7 @@ /x86_64/vmx_preemption_timer_test /x86_64/svm_vmcall_test /x86_64/sync_regs_test +/x86_64/vmx_apic_access_test /x86_64/vmx_close_while_nested_test /x86_64/vmx_dirty_log_test /x86_64/vmx_set_nested_state_test diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 7ebe71fbca53..30afbad36cd5 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -49,6 +49,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/state_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_preemption_timer_test TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test TEST_GEN_PROGS_x86_64 += x86_64/sync_regs_test +TEST_GEN_PROGS_x86_64 += x86_64/vmx_apic_access_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test diff --git a/tools/testing/selftests/kvm/include/x86_64/vmx.h b/tools/testing/selftests/kvm/include/x86_64/vmx.h index 54d624dd6c10..e78d7e26ba61 100644 --- a/tools/testing/selftests/kvm/include/x86_64/vmx.h +++ b/tools/testing/selftests/kvm/include/x86_64/vmx.h @@ -573,6 +573,10 @@ struct vmx_pages { void *eptp_hva; uint64_t eptp_gpa; void *eptp; + + void *apic_access_hva; + uint64_t apic_access_gpa; + void *apic_access; }; union vmx_basic { @@ -615,5 +619,7 @@ void nested_map_memslot(struct vmx_pages *vmx, struct kvm_vm *vm, uint32_t memslot, uint32_t eptp_memslot); void prepare_eptp(struct vmx_pages *vmx, struct kvm_vm *vm, uint32_t eptp_memslot); +void prepare_virtualize_apic_accesses(struct vmx_pages *vmx, struct kvm_vm *vm, + uint32_t eptp_memslot); #endif /* SELFTEST_KVM_VMX_H */ diff --git a/tools/testing/selftests/kvm/lib/x86_64/vmx.c b/tools/testing/selftests/kvm/lib/x86_64/vmx.c index f1e00d43eea2..2448b30e8efa 100644 --- a/tools/testing/selftests/kvm/lib/x86_64/vmx.c +++ b/tools/testing/selftests/kvm/lib/x86_64/vmx.c @@ -542,3 +542,12 @@ void prepare_eptp(struct vmx_pages *vmx, struct kvm_vm *vm, vmx->eptp_hva = addr_gva2hva(vm, (uintptr_t)vmx->eptp); vmx->eptp_gpa = addr_gva2gpa(vm, (uintptr_t)vmx->eptp); } + +void prepare_virtualize_apic_accesses(struct vmx_pages *vmx, struct kvm_vm *vm, + uint32_t eptp_memslot) +{ + vmx->apic_access = (void *)vm_vaddr_alloc(vm, getpagesize(), + 0x10000, 0, 0); + vmx->apic_access_hva = addr_gva2hva(vm, (uintptr_t)vmx->apic_access); + vmx->apic_access_gpa = addr_gva2gpa(vm, (uintptr_t)vmx->apic_access); +} diff --git a/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c new file mode 100644 index 000000000000..1f65342d6cb7 --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c @@ -0,0 +1,142 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * vmx_apic_access_test + * + * Copyright (C) 2020, Google LLC. + * + * This work is licensed under the terms of the GNU GPL, version 2. + * + * The first subtest simply checks to see that an L2 guest can be + * launched with a valid APIC-access address that is backed by a + * page of L1 physical memory. + * + * The second subtest sets the APIC-access address to a (valid) L1 + * physical address that is not backed by memory. KVM can't handle + * this situation, so resuming L2 should result in a KVM exit for + * internal error (emulation). This is not an architectural + * requirement. It is just a shortcoming of KVM. The internal error + * is unfortunate, but it's better than what used to happen! + */ + +#include "test_util.h" +#include "kvm_util.h" +#include "processor.h" +#include "vmx.h" + +#include +#include + +#include "kselftest.h" + +#define VCPU_ID 0 + +/* The virtual machine object. */ +static struct kvm_vm *vm; + +static void l2_guest_code(void) +{ + /* Exit to L1 */ + __asm__ __volatile__("vmcall"); +} + +static void l1_guest_code(struct vmx_pages *vmx_pages, unsigned long high_gpa) +{ +#define L2_GUEST_STACK_SIZE 64 + unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE]; + uint32_t control; + + GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages)); + GUEST_ASSERT(load_vmcs(vmx_pages)); + + /* Prepare the VMCS for L2 execution. */ + prepare_vmcs(vmx_pages, l2_guest_code, + &l2_guest_stack[L2_GUEST_STACK_SIZE]); + control = vmreadz(CPU_BASED_VM_EXEC_CONTROL); + control |= CPU_BASED_ACTIVATE_SECONDARY_CONTROLS; + vmwrite(CPU_BASED_VM_EXEC_CONTROL, control); + control = vmreadz(SECONDARY_VM_EXEC_CONTROL); + control |= SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES; + vmwrite(SECONDARY_VM_EXEC_CONTROL, control); + vmwrite(APIC_ACCESS_ADDR, vmx_pages->apic_access_gpa); + + /* Try to launch L2 with the memory-backed APIC-access address. */ + GUEST_SYNC(vmreadz(APIC_ACCESS_ADDR)); + GUEST_ASSERT(!vmlaunch()); + GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL); + + vmwrite(APIC_ACCESS_ADDR, high_gpa); + + /* Try to resume L2 with the unbacked APIC-access address. */ + GUEST_SYNC(vmreadz(APIC_ACCESS_ADDR)); + GUEST_ASSERT(!vmresume()); + GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL); + + GUEST_DONE(); +} + +int main(int argc, char *argv[]) +{ + unsigned long apic_access_addr = ~0ul; + unsigned int paddr_width; + unsigned int vaddr_width; + vm_vaddr_t vmx_pages_gva; + unsigned long high_gpa; + struct vmx_pages *vmx; + bool done = false; + + nested_vmx_check_supported(); + + vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code); + vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid()); + + kvm_get_cpu_address_width(&paddr_width, &vaddr_width); + high_gpa = (1ul << paddr_width) - getpagesize(); + if ((unsigned long)DEFAULT_GUEST_PHY_PAGES * getpagesize() > high_gpa) { + print_skip("No unbacked physical page available"); + exit(KSFT_SKIP); + } + + vmx = vcpu_alloc_vmx(vm, &vmx_pages_gva); + prepare_virtualize_apic_accesses(vmx, vm, 0); + vcpu_args_set(vm, VCPU_ID, 2, vmx_pages_gva, high_gpa); + + while (!done) { + volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID); + struct ucall uc; + + vcpu_run(vm, VCPU_ID); + if (apic_access_addr == high_gpa) { + TEST_ASSERT(run->exit_reason == + KVM_EXIT_INTERNAL_ERROR, + "Got exit reason other than KVM_EXIT_INTERNAL_ERROR: %u (%s)\n", + run->exit_reason, + exit_reason_str(run->exit_reason)); + TEST_ASSERT(run->internal.suberror == + KVM_INTERNAL_ERROR_EMULATION, + "Got internal suberror other than KVM_INTERNAL_ERROR_EMULATION: %u\n", + run->internal.suberror); + break; + } + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, + "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n", + run->exit_reason, + exit_reason_str(run->exit_reason)); + + switch (get_ucall(vm, VCPU_ID, &uc)) { + case UCALL_ABORT: + TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0], + __FILE__, uc.args[1]); + /* NOT REACHED */ + case UCALL_SYNC: + apic_access_addr = uc.args[1]; + break; + case UCALL_DONE: + done = true; + break; + default: + TEST_ASSERT(false, "Unknown ucall %lu", uc.cmd); + } + } + kvm_vm_free(vm); + return 0; +}