From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751992AbcGST7L (ORCPT ); Tue, 19 Jul 2016 15:59:11 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:50994 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751557AbcGST7I (ORCPT ); Tue, 19 Jul 2016 15:59:08 -0400 Date: Tue, 19 Jul 2016 15:58:56 -0400 From: Dave Jones To: Paolo Bonzini CC: Linux Kernel , Radim =?utf-8?B?S3LEjW3DocWZ?= , Subject: Re: RFC: silencing kvm unimplemented msr spew. Message-ID: <20160719195856.GA31453@fb.com> Mail-Followup-To: Dave Jones , Paolo Bonzini , Linux Kernel , Radim =?utf-8?B?S3LEjW3DocWZ?= , kvm@vger.kernel.org References: <20160715192729.GA4712@fb.com> <110045299.8101686.1468855610053.JavaMail.zimbra@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <110045299.8101686.1468855610053.JavaMail.zimbra@redhat.com> User-Agent: Mutt/1.6.0 (2016-04-01) X-Originating-IP: [2620:10d:c091:200::1:7e8b] X-ClientProxiedBy: SN1PR0701CA0070.namprd07.prod.outlook.com (10.163.126.38) To BY1PR15MB0054.namprd15.prod.outlook.com (10.161.97.14) X-MS-Office365-Filtering-Correlation-Id: 55d3c010-a2c1-499b-ec31-08d3b00f223a X-Microsoft-Exchange-Diagnostics: 1;BY1PR15MB0054;2:N/zyeo4RXeCpEfv4ZjOtuUIEo5XxmNPVFg5GuuWJB6C9QWe45RraF299X3x30USOt96I/bwHedOGGEGEjZqAY67UJsT0AZgq/yehcNfIMwXPZIIzVELJf/Mvug+/i2hw+uq9e61owBGJZbrD9ltPed66mupe/5+Wra3rujDk38W825OoHYaCCwMjP9CCrEBz;3:1R+Z/TOHWcxZS8REX2PbYj4bBw+ayrKyLuqLFiF9tlq67t/Qekxs/wBb+ciUS6PvmxZqZ4DO9UlOtXKZ1dB2X/wqsSiIKcyu8KZlOkZ5bzuWXIuWY/0CGDBAB9mBuvoz;25:F7tB+ufcmAJ/V9GHPibrAMjU4QtKRWyDXJmEyqvS9eYt9BimXp3fcaH+oHom21yrTkVq3l4lwmVnE7bNh7nSXlR+3DZi7YNVCuuHv566vg5/ud1Uk+1aWSKCvg7hkRji+3nX3DqJFk+/nREcW0QIMf5mCpPf35ondQyNsUH9O1vy8yKw8yhL00Vl6zeQWKMJpBJiX5wltMT+hRuD0QLEfrHp+2pOpJWrtzHx1pAJzemJgmP8Cz8irbpGnVKTDhLPocPutilI0q5waE0tzl86cuN/rR+A60N5WK/Z4U6l/KSaIDZoSzzdA+l/vv0RObjYrLU1pLL96Rmii4jxBCeFVJ+sQUcGh/f70P/OuE8GITD9kGkMqc0W3E66Q8v7qpBUJWQl3gpW3RGVcWdotnvRwDTKIyiavQD87ep0vfn/t68=;31:fqbv0xCDtcXmjz90S415gi3hwDcBAB1Czk/aAL0R1OfSmXGs/5jLuhEGw6kWADNBxE7kfnPJuLCtRDChJXQeyecVnicDQ6gQy9a3+OvlIhRczeHCHbYP9u+Up9OnOCLqknmo64EmboB44OGypT9gH/bCp8L1knTvTywnjRifAgbBZiA6N5SEl0A7SN8yKwWMkKO08fCwYHMBTPT2OqMJRA== X-Microsoft-Antispam: UriScan:;BCL:0;PCL:0;RULEID:;SRVR:BY1PR15MB0054; 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The conveniently named 'ignore_msrs' option initially > > seemed > > like it was what I was looking for, but it changes the printk instead > > of eliding it. > > > > Untested patch below converts ignore_msrs to a bitmask and adds an option to > > be > > completely silent. The idea being if after testing, things still work and you > > don't care about those messages, you can deploy in production with the > > silence option. > > > > Would something like this be acceptable ? > > Indeed, ignore_msrs does a completely different thing. It suppresses > general protection faults in the guest. It is related to behavior that > KVM injects in the guests, not to the things that KVM spews in the host. > > What about just downgrading the printf to KERN_DEBUG? You could simply > change from vcpu_unimpl to vcpu_debug, but it's probably a good idea to > keep the ratelimiting; there's a kvm_pr_unimpl, so maybe add a new > kvm_pr_debug and vcpu_pr_debug. Hm, we've certainly got a lot of options in terms of print primitives these days. We could just do this... diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 1c9c973a7dd9..a80b9a0a5f8c 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -423,7 +423,7 @@ struct kvm { #define kvm_debug(fmt, ...) \ pr_debug("kvm [%i]: " fmt, task_pid_nr(current), ## __VA_ARGS__) #define kvm_pr_unimpl(fmt, ...) \ - pr_err_ratelimited("kvm [%i]: " fmt, \ + pr_debug_ratelimited("kvm [%i]: " fmt, \ task_tgid_nr(current), ## __VA_ARGS__) /* The guest did something we don't support. */ Which I think would have the desired effect, and also gets us dynamic debug support for free. Thoughts ? Dave