From mboxrd@z Thu Jan 1 00:00:00 1970 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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 06B31C31E40 for ; Tue, 6 Aug 2019 15:46:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D5AB721871 for ; Tue, 6 Aug 2019 15:46:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732936AbfHFPqo (ORCPT ); Tue, 6 Aug 2019 11:46:44 -0400 Received: from mga03.intel.com ([134.134.136.65]:46146 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729161AbfHFPqo (ORCPT ); Tue, 6 Aug 2019 11:46:44 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga006.jf.intel.com ([10.7.209.51]) by orsmga103.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 06 Aug 2019 08:40:33 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,353,1559545200"; d="scan'208";a="179186990" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.41]) by orsmga006.jf.intel.com with ESMTP; 06 Aug 2019 08:40:33 -0700 Date: Tue, 6 Aug 2019 08:40:33 -0700 From: Sean Christopherson To: Vitaly Kuznetsov Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , Joerg Roedel , Jim Mattson Subject: Re: [PATCH v2 2/5] x86: KVM: svm: avoid flooding logs when skip_emulated_instruction() fails Message-ID: <20190806154033.GD27766@linux.intel.com> References: <20190806060150.32360-1-vkuznets@redhat.com> <20190806060150.32360-3-vkuznets@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190806060150.32360-3-vkuznets@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 06, 2019 at 08:01:47AM +0200, Vitaly Kuznetsov wrote: > When we're unable to skip instruction with kvm_emulate_instruction() we > will not advance RIP and most likely the guest will get stuck as > consequitive attempts to execute the same instruction will likely result > in the same behavior. > > As we're not supposed to see these messages under normal conditions, switch > to pr_err_once(). > > Signed-off-by: Vitaly Kuznetsov > Reviewed-by: Jim Mattson > --- > arch/x86/kvm/svm.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 7e843b340490..80f576e05112 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -782,7 +782,8 @@ static void skip_emulated_instruction(struct kvm_vcpu *vcpu) > if (!svm->next_rip) { > if (kvm_emulate_instruction(vcpu, EMULTYPE_SKIP) != > EMULATE_DONE) > - printk(KERN_DEBUG "%s: NOP\n", __func__); > + pr_err_once("KVM: %s: unable to skip instruction\n", > + __func__); IMO the proper fix would be to change skip_emulated_instruction() to return an int so that emulation failure can be reported back up the stack. It's a relatively minor change as there are a limited number of call sites to skip_emulated_instruction() in SVM and VMX. > return; > } > if (svm->next_rip - kvm_rip_read(vcpu) > MAX_INST_SIZE) > -- > 2.20.1 >