From nobody Wed Dec 31 05:05:48 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 06F07C4332F for ; Wed, 8 Nov 2023 01:10:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343760AbjKHBKF (ORCPT ); Tue, 7 Nov 2023 20:10:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235241AbjKHBKC (ORCPT ); Tue, 7 Nov 2023 20:10:02 -0500 Received: from mail-yw1-x1149.google.com (mail-yw1-x1149.google.com [IPv6:2607:f8b0:4864:20::1149]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5487C10CF for ; Tue, 7 Nov 2023 17:10:00 -0800 (PST) Received: by mail-yw1-x1149.google.com with SMTP id 00721157ae682-5afa071d100so126525187b3.1 for ; Tue, 07 Nov 2023 17:10:00 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1699405799; x=1700010599; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=QukVHBGeYSPz1+2qTuLcVIbH1kQU9rT6cdzN6AFG5KM=; b=IS9j7CXKvnl2UuQibEx4/5Sofxn9Wex5loBOdQLX61HDteZ6ZfpD/4Y5OnFkVBDZBH OmbCaiVGHk52Jo5/CsKjUOtfvM/3gKatnxckZYib2u/P2JyK7qga7sCqMDlZwPfQXrw0 9uqDFgYoNYzeB3GsVeCKGX5GYNNqVgLcruX7orISmB9jC48ECKUD1/pMFczfieGRcnGo HokhtWzm9/xvr8/7wFubUODsSf4tQUwEEBUKsXOS1GmEWdC2FKPh+wxtBKAdIw0LBkeO nujKalhI64wkOiTJk5B9k2juwgf3TsK/1A0iKwhaVr3sARc2T1VEcCdVxx1M3XFbF/jE 5ZtA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1699405799; x=1700010599; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=QukVHBGeYSPz1+2qTuLcVIbH1kQU9rT6cdzN6AFG5KM=; b=CmWQnYd8nSCP9/dG8n042eCd3VtLXXeYsj1yO5pJAfdj+VSfan9ubdR8uURR5zsfG0 IKxtmJD/OX8XtZEedzYAw2hQ8E9yatGE1NzDhJpg+WJ3JNxo2J0Sw6nX9dYWJ2aRuceU bk7J0UojixIOwOpNf4BrMy4RDqotDjdgA6f6a++QwZRw0ibZwi5pSUNLDJeSJz3Y3Y0d WwLbyTytdRuLO8QIQU3l3ZeuOrDcpovSP1oT+JSPwMh5SIVluSYbxc8e7PWW5dlxEPnX VlJlLnVS1Hr5BArtvMZOEgBdGpt+xPp/6adPwEZQcE/p3/ftY6pTGPO0Htocg3CjNheA cdww== X-Gm-Message-State: AOJu0YyKmOg3rUL7kFnvXRSfbtQeLvvmSjZzsiiFWAhb+XCOeeka1K9L 3vd0kqjoCcBNs11wWY3WNlEKLEwLsH0= X-Google-Smtp-Source: AGHT+IG5EDfRYHa9zbeZsaffwrzHpUf2L31GOHkP08fuh//RS6O1PJrNN1NM4sIC7p9V4KivNphMc2ySjXU= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a0d:d745:0:b0:5a7:b672:4d88 with SMTP id z66-20020a0dd745000000b005a7b6724d88mr7106ywd.0.1699405799597; Tue, 07 Nov 2023 17:09:59 -0800 (PST) Reply-To: Sean Christopherson Date: Tue, 7 Nov 2023 17:09:53 -0800 In-Reply-To: <20231108010953.560824-1-seanjc@google.com> Mime-Version: 1.0 References: <20231108010953.560824-1-seanjc@google.com> X-Mailer: git-send-email 2.42.0.869.gea05f2083d-goog Message-ID: <20231108010953.560824-3-seanjc@google.com> Subject: [PATCH v2 2/2] KVM: selftests: Add logic to detect if ioctl() failed because VM was killed From: Sean Christopherson To: Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Christopherson , Michal Luczaj , Oliver Upton , Colton Lewis Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Add yet another macro to the VM/vCPU ioctl() framework to detect when an ioctl() failed because KVM killed/bugged the VM, i.e. when there was nothing wrong with the ioctl() itself. If KVM kills a VM, e.g. by way of a failed KVM_BUG_ON(), all subsequent VM and vCPU ioctl()s will fail with -EIO, which can be quite misleading and ultimately waste user/developer time. Use KVM_CHECK_EXTENSION on KVM_CAP_USER_MEMORY to detect if the VM is dead and/or bug, as KVM doesn't provide a dedicated ioctl(). Using a heuristic is obviously less than ideal, but practically speaking the logic is bulletproof barring a KVM change, and any such change would arguably break userspace, e.g. if KVM returns something other than -EIO. Without the detection, tearing down a bugged VM yields a cryptic failure when deleting memslots: =3D=3D=3D=3D Test Assertion Failure =3D=3D=3D=3D lib/kvm_util.c:689: !ret pid=3D45131 tid=3D45131 errno=3D5 - Input/output error 1 0x00000000004036c3: __vm_mem_region_delete at kvm_util.c:689 2 0x00000000004042f0: kvm_vm_free at kvm_util.c:724 (discriminator 12) 3 0x0000000000402929: race_sync_regs at sync_regs_test.c:193 4 0x0000000000401cab: main at sync_regs_test.c:334 (discriminator 6) 5 0x0000000000416f13: __libc_start_call_main at libc-start.o:? 6 0x000000000041855f: __libc_start_main_impl at ??:? 7 0x0000000000401d40: _start at ??:? KVM_SET_USER_MEMORY_REGION failed, rc: -1 errno: 5 (Input/output error) Which morphs into a more pointed error message with the detection: =3D=3D=3D=3D Test Assertion Failure =3D=3D=3D=3D lib/kvm_util.c:689: false pid=3D80347 tid=3D80347 errno=3D5 - Input/output error 1 0x00000000004039ab: __vm_mem_region_delete at kvm_util.c:689 (discri= minator 5) 2 0x0000000000404660: kvm_vm_free at kvm_util.c:724 (discriminator 12) 3 0x0000000000402ac9: race_sync_regs at sync_regs_test.c:193 4 0x0000000000401cb7: main at sync_regs_test.c:334 (discriminator 6) 5 0x0000000000418263: __libc_start_call_main at libc-start.o:? 6 0x00000000004198af: __libc_start_main_impl at ??:? 7 0x0000000000401d90: _start at ??:? KVM killed/bugged the VM, check the kernel log for clues Suggested-by: Michal Luczaj Cc: Oliver Upton Cc: Colton Lewis Signed-off-by: Sean Christopherson --- .../selftests/kvm/include/kvm_util_base.h | 39 ++++++++++++++++--- tools/testing/selftests/kvm/lib/kvm_util.c | 2 +- 2 files changed, 35 insertions(+), 6 deletions(-) diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/te= sting/selftests/kvm/include/kvm_util_base.h index 1f6193dc7d3a..c7717942ddbb 100644 --- a/tools/testing/selftests/kvm/include/kvm_util_base.h +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h @@ -282,11 +282,40 @@ static __always_inline void static_assert_is_vm(struc= t kvm_vm *vm) { } kvm_do_ioctl((vm)->fd, cmd, arg); \ }) =20 +/* + * Assert that a VM or vCPU ioctl() succeeded, with extra magic to detect = if + * the ioctl() failed because KVM killed/bugged the VM. To detect a dead = VM, + * probe KVM_CAP_USER_MEMORY, which (a) has been supported by KVM since be= fore + * selftests existed and (b) should never outright fail, i.e. is supposed = to + * return 0 or 1. If KVM kills a VM, KVM returns -EIO for all ioctl()s fo= r the + * VM and its vCPUs, including KVM_CHECK_EXTENSION. + */ +#define __TEST_ASSERT_VM_VCPU_IOCTL(cond, name, ret, vm) \ +do { \ + int __errno =3D errno; \ + \ + static_assert_is_vm(vm); \ + \ + if (cond) \ + break; \ + \ + if (errno =3D=3D EIO && \ + __vm_ioctl(vm, KVM_CHECK_EXTENSION, (void *)KVM_CAP_USER_MEMORY) < 0)= { \ + TEST_ASSERT(errno =3D=3D EIO, "KVM killed the VM, should return -EIO"); \ + TEST_FAIL("KVM killed/bugged the VM, check the kernel log for clues"); \ + } \ + errno =3D __errno; \ + TEST_ASSERT(cond, __KVM_IOCTL_ERROR(name, ret)); \ +} while (0) + +#define TEST_ASSERT_VM_VCPU_IOCTL(cond, cmd, ret, vm) \ + __TEST_ASSERT_VM_VCPU_IOCTL(cond, #cmd, ret, vm) + #define vm_ioctl(vm, cmd, arg) \ ({ \ int ret =3D __vm_ioctl(vm, cmd, arg); \ \ - TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(#cmd, ret)); \ + __TEST_ASSERT_VM_VCPU_IOCTL(!ret, #cmd, ret, vm); \ }) =20 static __always_inline void static_assert_is_vcpu(struct kvm_vcpu *vcpu) {= } @@ -301,7 +330,7 @@ static __always_inline void static_assert_is_vcpu(struc= t kvm_vcpu *vcpu) { } ({ \ int ret =3D __vcpu_ioctl(vcpu, cmd, arg); \ \ - TEST_ASSERT(!ret, __KVM_IOCTL_ERROR(#cmd, ret)); \ + __TEST_ASSERT_VM_VCPU_IOCTL(!ret, #cmd, ret, (vcpu)->vm); \ }) =20 /* @@ -312,7 +341,7 @@ static inline int vm_check_cap(struct kvm_vm *vm, long = cap) { int ret =3D __vm_ioctl(vm, KVM_CHECK_EXTENSION, (void *)cap); =20 - TEST_ASSERT(ret >=3D 0, KVM_IOCTL_ERROR(KVM_CHECK_EXTENSION, ret)); + TEST_ASSERT_VM_VCPU_IOCTL(ret >=3D 0, KVM_CHECK_EXTENSION, ret, vm); return ret; } =20 @@ -371,7 +400,7 @@ static inline int vm_get_stats_fd(struct kvm_vm *vm) { int fd =3D __vm_ioctl(vm, KVM_GET_STATS_FD, NULL); =20 - TEST_ASSERT(fd >=3D 0, KVM_IOCTL_ERROR(KVM_GET_STATS_FD, fd)); + TEST_ASSERT_VM_VCPU_IOCTL(fd >=3D 0, KVM_GET_STATS_FD, fd, vm); return fd; } =20 @@ -583,7 +612,7 @@ static inline int vcpu_get_stats_fd(struct kvm_vcpu *vc= pu) { int fd =3D __vcpu_ioctl(vcpu, KVM_GET_STATS_FD, NULL); =20 - TEST_ASSERT(fd >=3D 0, KVM_IOCTL_ERROR(KVM_GET_STATS_FD, fd)); + TEST_ASSERT_VM_VCPU_IOCTL(fd >=3D 0, KVM_CHECK_EXTENSION, fd, vcpu->vm); return fd; } =20 diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/sel= ftests/kvm/lib/kvm_util.c index 7a8af1821f5d..c847f942cd38 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -1227,7 +1227,7 @@ struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, uin= t32_t vcpu_id) vcpu->vm =3D vm; vcpu->id =3D vcpu_id; vcpu->fd =3D __vm_ioctl(vm, KVM_CREATE_VCPU, (void *)(unsigned long)vcpu_= id); - TEST_ASSERT(vcpu->fd >=3D 0, KVM_IOCTL_ERROR(KVM_CREATE_VCPU, vcpu->fd)); + TEST_ASSERT_VM_VCPU_IOCTL(vcpu->fd >=3D 0, KVM_CREATE_VCPU, vcpu->fd, vm); =20 TEST_ASSERT(vcpu_mmap_sz() >=3D sizeof(*vcpu->run), "vcpu mmap size " "smaller than expected, vcpu_mmap_sz: %i expected_min: %zi", --=20 2.42.0.869.gea05f2083d-goog