From patchwork Thu Jul 29 13:39:30 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Edmondson X-Patchwork-Id: 12408783 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 DD35EC432BE for ; Thu, 29 Jul 2021 13:46:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C94DA60EB5 for ; Thu, 29 Jul 2021 13:46:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237662AbhG2NqN (ORCPT ); Thu, 29 Jul 2021 09:46:13 -0400 Received: from wforward5-smtp.messagingengine.com ([64.147.123.35]:47681 "EHLO wforward5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237661AbhG2NqK (ORCPT ); Thu, 29 Jul 2021 09:46:10 -0400 X-Greylist: delayed 384 seconds by postgrey-1.27 at vger.kernel.org; Thu, 29 Jul 2021 09:46:10 EDT Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailforward.west.internal (Postfix) with ESMTP id F30481AC085A; Thu, 29 Jul 2021 09:39:45 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute6.internal (MEProxy); Thu, 29 Jul 2021 09:39:46 -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=dbxSlvCauQQwbKG7nfBtMKR3T/qgRW2Y67hYThu0ZP0=; b=LRXoR1eg Oy+WAxGhZe+9w6b30C0mquW66U4GnBenqCGXQu++wkI4SayI0UbGIuj402UrV66d sx4HJsqyPZ2wlp2AAhArvCe4PTqTMtBx6RRNNTI52mLsLnpY3beJ+uV0BBf955sx HJ44D4XFEsWVNIZyNtbrh0GRHFaSAYquoUCnQIRXuVjb9zJE6hvqTIAadjbyCfIh Jnxl2BTQ65Rb0EkMyGvUPalQQzgj3ECtKwr1WLmDDN1BdaTCleVzSwL+lAF+wems BNI4+F0GiAt8DS5OKTgdQJVckNLnlErTtP7J1rIOEMIWVRMk4mFm9SQvGfsiHyex VeLtJlAOhqdMSA== X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedvtddrheefgddviecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenuc fjughrpefhvffufffkofgjfhgggfestdekredtredttdenucfhrhhomhepffgrvhhiugcu gfgumhhonhgushhonhcuoegurghvihgurdgvughmohhnughsohhnsehorhgrtghlvgdrtg homheqnecuggftrfgrthhtvghrnhepudefteejgfefhfdtjefhhedtffethfetkeehgfel heffhfeihfeglefgjedtheeknecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpe hmrghilhhfrhhomhepuggrvhhiugdrvggumhhonhgushhonhesohhrrggtlhgvrdgtohhm X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Thu, 29 Jul 2021 09:39:43 -0400 (EDT) Received: from localhost (disaster-area.hh.sledj.net [local]) by disaster-area.hh.sledj.net (OpenSMTPD) with ESMTPA id b1e2ac23; Thu, 29 Jul 2021 13:39:32 +0000 (UTC) From: David Edmondson To: linux-kernel@vger.kernel.org Cc: Thomas Gleixner , Joerg Roedel , Ingo Molnar , Jim Mattson , kvm@vger.kernel.org, Borislav Petkov , David Matlack , Paolo Bonzini , "H. Peter Anvin" , x86@kernel.org, Wanpeng Li , Vitaly Kuznetsov , Sean Christopherson , David Edmondson , Joao Martins Subject: [PATCH v3 2/3] KVM: x86: On emulation failure, convey the exit reason, etc. to userspace Date: Thu, 29 Jul 2021 14:39:30 +0100 Message-Id: <20210729133931.1129696-3-david.edmondson@oracle.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210729133931.1129696-1-david.edmondson@oracle.com> References: <20210729133931.1129696-1-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, etc. 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 | 5 ++++ arch/x86/kvm/vmx/vmx.c | 5 +--- arch/x86/kvm/x86.c | 53 ++++++++++++++++++++++++++------- include/uapi/linux/kvm.h | 7 +++++ 4 files changed, 56 insertions(+), 14 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index dfb902930cdc..17da43c1aa67 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -1630,6 +1630,11 @@ 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 *data, unsigned int ndata); +void kvm_prepare_emulation_failure_exit_with_reason(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 fefdecb0ff3d..a8d303c7c099 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_with_reason(vcpu, false); return 0; } diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a4fd10604f72..a97bacd8922f 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7456,7 +7456,9 @@ 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, + void *data, unsigned int ndata) { struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt; u32 insn_size = ctxt->fetch.end - ctxt->fetch.data; @@ -7464,10 +7466,10 @@ static void prepare_emulation_failure_exit(struct kvm_vcpu *vcpu) run->exit_reason = KVM_EXIT_INTERNAL_ERROR; run->emulation_failure.suberror = KVM_INTERNAL_ERROR_EMULATION; - run->emulation_failure.ndata = 0; + run->emulation_failure.ndata = 1; /* Always include the flags. */ run->emulation_failure.flags = 0; - if (insn_size) { + if (instruction_bytes && insn_size) { run->emulation_failure.ndata = 3; run->emulation_failure.flags |= KVM_INTERNAL_ERROR_EMULATION_FLAG_INSTRUCTION_BYTES; @@ -7477,7 +7479,42 @@ static void prepare_emulation_failure_exit(struct kvm_vcpu *vcpu) memcpy(run->emulation_failure.insn_bytes, ctxt->fetch.data, insn_size); } + + ndata = min((size_t)ndata, sizeof(run->internal.data) - + run->emulation_failure.ndata * sizeof(u64)); + if (ndata) { + unsigned int offset = + offsetof(struct kvm_run, emulation_failure.flags) + + run->emulation_failure.ndata * sizeof(u64); + + memcpy((void *)run + offset, data, ndata); + run->emulation_failure.ndata += ndata / sizeof(u64); + } +} +EXPORT_SYMBOL_GPL(kvm_prepare_emulation_failure_exit); + +void kvm_prepare_emulation_failure_exit_with_reason(struct kvm_vcpu *vcpu, + bool instruction_bytes) +{ + struct { + __u64 exit_reason; + __u64 exit_info1; + __u64 exit_info2; + __u32 intr_info; + __u32 error_code; + } exit_reason; + + static_call(kvm_x86_get_exit_info)(vcpu, + &exit_reason.exit_reason, + &exit_reason.exit_info1, + &exit_reason.exit_info2, + &exit_reason.intr_info, + &exit_reason.error_code); + + kvm_prepare_emulation_failure_exit(vcpu, instruction_bytes, + &exit_reason, sizeof(exit_reason)); } +EXPORT_SYMBOL_GPL(kvm_prepare_emulation_failure_exit_with_reason); static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type) { @@ -7493,16 +7530,14 @@ 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_with_reason(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_with_reason(vcpu, false); return 0; } @@ -12095,9 +12130,7 @@ 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_with_reason(vcpu, false); return 0; } diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index d9e4aabcb31a..f1ef4117b824 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -397,6 +397,12 @@ struct kvm_run { * "ndata" is correct, that new fields are enumerated in "flags", * and that each flag enumerates fields that are 64-bit aligned * and sized (so that ndata+internal.data[] is valid/accurate). + * + * Space beyond the defined fields may be used to + * store arbitrary debug information relating to the + * emulation failure. It is accounted for in "ndata" + * but otherwise unspecified and is not represented in + * "flags". */ struct { __u32 suberror; @@ -404,6 +410,7 @@ struct kvm_run { __u64 flags; __u8 insn_size; __u8 insn_bytes[15]; + /* Arbitrary debug data may follow. */ } emulation_failure; /* KVM_EXIT_OSI */ struct {