From patchwork Tue Jul 6 10:12:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Edmondson X-Patchwork-Id: 12360207 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BB461C07E9B for ; Tue, 6 Jul 2021 10:12:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A66D1619AF for ; Tue, 6 Jul 2021 10:12:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231344AbhGFKPD (ORCPT ); Tue, 6 Jul 2021 06:15:03 -0400 Received: from forward3-smtp.messagingengine.com ([66.111.4.237]:42519 "EHLO forward3-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231299AbhGFKPC (ORCPT ); Tue, 6 Jul 2021 06:15:02 -0400 Received: from compute2.internal (compute2.nyi.internal [10.202.2.42]) by mailforward.nyi.internal (Postfix) with ESMTP id 555C21940619; Tue, 6 Jul 2021 06:12:23 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute2.internal (MEProxy); Tue, 06 Jul 2021 06:12:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:date:from :in-reply-to:message-id:mime-version:references:subject:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm3; bh=50e02u+t8XVaFNF+IXucFs9YC7xNugTJ9Gt13UVtu6w=; b=Wm7bGfgV krUTAQV3tlyTyGAi3IO9PiZtgFDbRuL+KEqAoEF4Ninb/SFvZkaIzJ3VdaSw0Sve 1J3b8Jgl68QFtDW6zl9I6UQ4EXFQpZYBA6nshmnl99+qngyzVj1L5F/0rN1tXN1n n/I1Vyi8ymuxmrsn7LhIO8LAwb7iJfR6oL72UOHJHdPVGtB4xp0St50nPbfePiWG sgh+x3oQxf+Yc2j2mSiWe5pv0svQ8WYi5rsgfbhJbfEn6c95p46n2ZnIGflOIo5j /nVAJFNbxHPPVrAIcM/fBlEtafE8XA3Gj+wvdW8rcYH41oIvB19OAJ1EFsjsGSRr HIXwCMiAvTx81g== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrfeejiedgvddvucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddmne cujfgurhephffvufffkffojghfggfgsedtkeertdertddtnecuhfhrohhmpeffrghvihgu ucfgughmohhnughsohhnuceouggrvhhiugdrvggumhhonhgushhonhesohhrrggtlhgvrd gtohhmqeenucggtffrrghtthgvrhhnpedufeetjefgfefhtdejhfehtdfftefhteekhefg leehfffhiefhgeelgfejtdehkeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmh epmhgrihhlfhhrohhmpegurghvihgurdgvughmohhnughsohhnsehorhgrtghlvgdrtgho mh X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 6 Jul 2021 06:12:20 -0400 (EDT) Received: from localhost (disaster-area.hh.sledj.net [local]) by disaster-area.hh.sledj.net (OpenSMTPD) with ESMTPA id e125f3ea; Tue, 6 Jul 2021 10:12:07 +0000 (UTC) From: David Edmondson To: linux-kernel@vger.kernel.org Cc: Wanpeng Li , Jim Mattson , Sean Christopherson , Borislav Petkov , Vitaly Kuznetsov , Joerg Roedel , kvm@vger.kernel.org, Paolo Bonzini , David Matlack , Thomas Gleixner , x86@kernel.org, Ingo Molnar , "H. Peter Anvin" , David Edmondson , Joao Martins Subject: [PATCH v2 2/2] KVM: x86: On emulation failure, convey the exit reason to userspace Date: Tue, 6 Jul 2021 11:12:07 +0100 Message-Id: <20210706101207.2993686-3-david.edmondson@oracle.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210706101207.2993686-1-david.edmondson@oracle.com> References: <20210706101207.2993686-1-david.edmondson@oracle.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Should instruction emulation fail, include the VM exit reason in the emulation_failure data passed to userspace, in order that the VMM can report it as a debugging aid when describing the failure. Suggested-by: Joao Martins Signed-off-by: David Edmondson --- arch/x86/include/asm/kvm_host.h | 2 ++ arch/x86/kvm/vmx/vmx.c | 5 +---- arch/x86/kvm/x86.c | 22 +++++++++++++--------- include/uapi/linux/kvm.h | 7 +++++++ 4 files changed, 23 insertions(+), 13 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 0ee580c68839..2e411e26e40e 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1630,6 +1630,8 @@ extern u64 kvm_mce_cap_supported; int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type); int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu, void *insn, int insn_len); +void kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu, + bool instruction_bytes); void kvm_enable_efer_bits(u64); bool kvm_valid_efer(struct kvm_vcpu *vcpu, u64 efer); diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index d9a4d6cf6406..4fb240204c2c 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5367,10 +5367,7 @@ static int handle_invalid_guest_state(struct kvm_vcpu *vcpu) if (vmx->emulation_required && !vmx->rmode.vm86_active && vcpu->arch.exception.pending) { - vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; - vcpu->run->internal.suberror = - KVM_INTERNAL_ERROR_EMULATION; - vcpu->run->internal.ndata = 0; + kvm_prepare_emulation_failure_exit(vcpu, false); return 0; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 17468d983fbd..bf30b445b65d 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7452,7 +7452,8 @@ void kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip) } EXPORT_SYMBOL_GPL(kvm_inject_realmode_interrupt); -static void prepare_emulation_failure_exit(struct kvm_vcpu *vcpu) +void kvm_prepare_emulation_failure_exit(struct kvm_vcpu *vcpu, + bool instruction_bytes) { struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt; u32 insn_size = ctxt->fetch.end - ctxt->fetch.data; @@ -7463,7 +7464,7 @@ static void prepare_emulation_failure_exit(struct kvm_vcpu *vcpu) run->emulation_failure.ndata = 0; run->emulation_failure.flags = 0; - if (insn_size) { + if (insn_size && instruction_bytes) { run->emulation_failure.ndata = 3; run->emulation_failure.flags |= KVM_INTERNAL_ERROR_EMULATION_FLAG_INSTRUCTION_BYTES; @@ -7473,7 +7474,14 @@ static void prepare_emulation_failure_exit(struct kvm_vcpu *vcpu) memcpy(run->emulation_failure.insn_bytes, ctxt->fetch.data, insn_size); } + + run->emulation_failure.ndata = 4; + run->emulation_failure.flags |= + KVM_INTERNAL_ERROR_EMULATION_FLAG_EXIT_REASON; + run->emulation_failure.exit_reason = + static_call(kvm_x86_get_exit_reason)(vcpu); } +EXPORT_SYMBOL_GPL(kvm_prepare_emulation_failure_exit); static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type) { @@ -7489,16 +7497,14 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type) if (kvm->arch.exit_on_emulation_error || (emulation_type & EMULTYPE_SKIP)) { - prepare_emulation_failure_exit(vcpu); + kvm_prepare_emulation_failure_exit(vcpu, true); return 0; } kvm_queue_exception(vcpu, UD_VECTOR); if (!is_guest_mode(vcpu) && static_call(kvm_x86_get_cpl)(vcpu) == 0) { - vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; - vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; - vcpu->run->internal.ndata = 0; + kvm_prepare_emulation_failure_exit(vcpu, false); return 0; } @@ -12092,9 +12098,7 @@ int kvm_handle_memory_failure(struct kvm_vcpu *vcpu, int r, * doesn't seem to be a real use-case behind such requests, just return * KVM_EXIT_INTERNAL_ERROR for now. */ - vcpu->run->exit_reason = KVM_EXIT_INTERNAL_ERROR; - vcpu->run->internal.suberror = KVM_INTERNAL_ERROR_EMULATION; - vcpu->run->internal.ndata = 0; + kvm_prepare_emulation_failure_exit(vcpu, false); return 0; } diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index d9e4aabcb31a..863195371272 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -282,6 +282,7 @@ struct kvm_xen_exit { /* Flags that describe what fields in emulation_failure hold valid data. */ #define KVM_INTERNAL_ERROR_EMULATION_FLAG_INSTRUCTION_BYTES (1ULL << 0) +#define KVM_INTERNAL_ERROR_EMULATION_FLAG_EXIT_REASON (1ULL << 1) /* for KVM_RUN, returned by mmap(vcpu_fd, offset=0) */ struct kvm_run { @@ -404,6 +405,12 @@ struct kvm_run { __u64 flags; __u8 insn_size; __u8 insn_bytes[15]; + /* + * The "exit reason" extracted from the + * VMCS/VMCB that was the cause of attempted + * emulation. + */ + __u64 exit_reason; } emulation_failure; /* KVM_EXIT_OSI */ struct {