Received: by 2002:ac0:98c7:0:0:0:0:0 with SMTP id g7-v6csp3690799imd; Mon, 29 Oct 2018 10:49:05 -0700 (PDT) X-Google-Smtp-Source: AJdET5cSbN0iGvXqWSquF0EosNPtu8lnDH0iFZ1ghnSVcWNsTFh2JoRUceOhgEMe8Kgtw/uGRTLu X-Received: by 2002:a17:902:1ea:: with SMTP id b97-v6mr15615938plb.152.1540835345552; Mon, 29 Oct 2018 10:49:05 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1540835345; cv=none; d=google.com; s=arc-20160816; b=J7fYCRYDIgr3z9FxEkYKa2eBeyOuRW6Z9Ocm3/2dhnn7m+wldjcPTxTBX3V+gojTTe LiWWayGFsXkIPjbfJA840Rl7rPvadCMcpLCsvU9lq5bXCZ3MMOg7Kqzaf3VOlpYqMETz qI3VI23e2B/WDy3ITqaFYuFqnvmdZYtFRIzVHfXSZGBn9IVdNxR5SSxWP+vsV1TJeYGZ X4fI8VTYy6tNH4Mvq7vLR9ulrf4Tr0afeApK8eeXUQvOwQRLwa12gCAH+khLQ/63U9Jh /dAlwohhKH3HmEh/DEAS7Thbfh8tVDQ7dtnGWkIaIL18Rqr1nX4bzMCRUUIABnjO5+/B rl2A== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:autocrypt:openpgp:from:references:cc:to:subject; bh=SkZozfeMI0VaX69Oux6wQunKPYaFdUlW/JfoornDenM=; b=otcqM7ib8JZPZOg9FzplCptko2rJzVEp8LM1uIeRXado5rx9BLNAG6CpfEUwR6U2AI S3LAIF9MSZSDD2wT3AOIeUlhsKkcd0Q5Mkc303w8uWPYb8Kgv8BHeqALTB3t7Z9PYvdE aAtc01qGjzY7puK0clgcF+T/nKYvbuBTu1alQci/CFNXYdedFiGbAlrnJ7jThyzIkcse /+lA5s9IFi6MaW6GkoNOShmFVgfgdDRB4c4XKY9wZbtoCZnFIc6dl8FrXaA3PJxLhXG5 pg0Qqy6u3FI46K8EfvOBxeB4jxId2Qg6aQ6VoUh4sm5BnaU70kxBCTpsvvwRG8jVyIqJ iqYg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id o3-v6si6198pgp.251.2018.10.29.10.48.50; Mon, 29 Oct 2018 10:49:05 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727773AbeJ3CiE (ORCPT + 99 others); Mon, 29 Oct 2018 22:38:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:1297 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726532AbeJ3CiE (ORCPT ); Mon, 29 Oct 2018 22:38:04 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0091A317B2D1; Mon, 29 Oct 2018 17:48:25 +0000 (UTC) Received: from [10.36.112.24] (ovpn-112-24.ams2.redhat.com [10.36.112.24]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 7FF72608E0; Mon, 29 Oct 2018 17:48:17 +0000 (UTC) Subject: Re: [PATCH v13 08/12] KVM: x86: Add Intel PT context switch for each vcpu To: Alexander Shishkin , Luwei Kang , kvm@vger.kernel.org, x86@kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com, rkrcmar@redhat.com, joro@8bytes.org, songliubraving@fb.com, peterz@infradead.org, kstewart@linuxfoundation.org, gregkh@linuxfoundation.org, thomas.lendacky@amd.com, konrad.wilk@oracle.com, mattst88@gmail.com, Janakarajan.Natarajan@amd.com, dwmw@amazon.co.uk, jpoimboe@redhat.com, marcorr@google.com, ubizjak@gmail.com, sean.j.christopherson@intel.com, jmattson@google.com, linux-kernel@vger.kernel.org, Chao Peng References: <1540368316-12998-1-git-send-email-luwei.kang@intel.com> <1540368316-12998-9-git-send-email-luwei.kang@intel.com> <87a7n37iuf.fsf@ashishki-desk.ger.corp.intel.com> From: Paolo Bonzini Openpgp: preference=signencrypt Autocrypt: addr=pbonzini@redhat.com; prefer-encrypt=mutual; keydata= xsEhBFRCcBIBDqDGsz4K0zZun3jh+U6Z9wNGLKQ0kSFyjN38gMqU1SfP+TUNQepFHb/Gc0E2 CxXPkIBTvYY+ZPkoTh5xF9oS1jqI8iRLzouzF8yXs3QjQIZ2SfuCxSVwlV65jotcjD2FTN04 hVopm9llFijNZpVIOGUTqzM4U55sdsCcZUluWM6x4HSOdw5F5Utxfp1wOjD/v92Lrax0hjiX DResHSt48q+8FrZzY+AUbkUS+Jm34qjswdrgsC5uxeVcLkBgWLmov2kMaMROT0YmFY6A3m1S P/kXmHDXxhe23gKb3dgwxUTpENDBGcfEzrzilWueOeUWiOcWuFOed/C3SyijBx3Av/lbCsHU Vx6pMycNTdzU1BuAroB+Y3mNEuW56Yd44jlInzG2UOwt9XjjdKkJZ1g0P9dwptwLEgTEd3Fo UdhAQyRXGYO8oROiuh+RZ1lXp6AQ4ZjoyH8WLfTLf5g1EKCTc4C1sy1vQSdzIRu3rBIjAvnC tGZADei1IExLqB3uzXKzZ1BZ+Z8hnt2og9hb7H0y8diYfEk2w3R7wEr+Ehk5NQsT2MPI2QBd wEv1/Aj1DgUHZAHzG1QN9S8wNWQ6K9DqHZTBnI1hUlkp22zCSHK/6FwUCuYp1zcAEQEAAc0f UGFvbG8gQm9uemluaSA8Ym9uemluaUBnbnUub3JnPsLBTQQTAQIAIwUCVEJ7AwIbAwcLCQgH AwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEH4VEAzNNmmxNcwOniaZVLsuy1lW/ntYCA0Caz0i sHpmecK8aWlvL9wpQCk4GlOX9L1emyYXZPmzIYB0IRqmSzAlZxi+A2qm9XOxs5gJ2xqMEXX5 FMtUH3kpkWWJeLqe7z0EoQdUI4EG988uv/tdZyqjUn2XJE+K01x7r3MkUSFz/HZKZiCvYuze VlS0NTYdUt5jBXualvAwNKfxEkrxeHjxgdFHjYWhjflahY7TNRmuqPM/Lx7wAuyoDjlYNE40 Z+Kun4/KjMbjgpcF4Nf3PJQR8qXI6p3so2qsSn91tY7DFSJO6v2HwFJkC2jU95wxfNmTEUZc znXahYbVOwCDJRuPrE5GKFd/XJU9u5hNtr/uYipHij01WXal2cce1S5mn1/HuM1yo1u8xdHy IupCd57EWI948e8BlhpujUCU2tzOb2iYS0kpmJ9/oLVZrOcSZCcCl2P0AaCAsj59z2kwQS9D du0WxUs8waso0Qq6tDEHo8yLCOJDzSz4oojTtWe4zsulVnWV+wu70AioemAT8S6JOtlu60C5 dHgQUD1Tp+ReXpDKXmjbASJx4otvW0qah3o6JaqO79tbDqIvncu3tewwp6c85uZd48JnIOh3 utBAu684nJakbbvZUGikJfxd887ATQRUQnHuAQgAx4dxXO6/Zun0eVYOnr5GRl76+2UrAAem Vv9Yfn2PbDIbxXqLff7oyVJIkw4WdhQIIvvtu5zH24iYjmdfbg8iWpP7NqxUQRUZJEWbx2CR wkMHtOmzQiQ2tSLjKh/cHeyFH68xjeLcinR7jXMrHQK+UCEw6jqi1oeZzGvfmxarUmS0uRuf fAb589AJW50kkQK9VD/9QC2FJISSUDnRC0PawGSZDXhmvITJMdD4TjYrePYhSY4uuIV02v02 8TVAaYbIhxvDY0hUQE4r8ZbGRLn52bEzaIPgl1p/adKfeOUeMReg/CkyzQpmyB1TSk8lDMxQ zCYHXAzwnGi8WU9iuE1P0wARAQABwsEzBBgBAgAJBQJUQnHuAhsMAAoJEH4VEAzNNmmxp1EO oJy0uZggJm7gZKeJ7iUpeX4eqUtqelUw6gU2daz2hE/jsxsTbC/w5piHmk1H1VWDKEM4bQBT uiJ0bfo55SWsUNN+c9hhIX+Y8LEe22izK3w7mRpvGcg+/ZRG4DEMHLP6JVsv5GMpoYwYOmHn plOzCXHvmdlW0i6SrMsBDl9rw4AtIa6bRwWLim1lQ6EM3PWifPrWSUPrPcw4OLSwFk0CPqC4 HYv/7ZnASVkR5EERFF3+6iaaVi5OgBd81F1TCvCX2BEyIDRZLJNvX3TOd5FEN+lIrl26xecz 876SvcOb5SL5SKg9/rCBufdPSjojkGFWGziHiFaYhbuI2E+NfWLJtd+ZvWAAV+O0d8vFFSvr iy9enJ8kxJwhC0ECbSKFY+W1eTIhMD3aeAKY90drozWEyHhENf4l/V+Ja5vOnW+gCDQkGt2Y 1lJAPPSIqZKvHzGShdh8DduC0U3xYkfbGAUvbxeepjgzp0uEnBXfPTy09JGpgWbg0w91GyfT /ujKaGd4vxG2Ei+MMNDmS1SMx7wu0evvQ5kT9NPzyq8R2GIhVSiAd2jioGuTjX6AZCFv3ToO 53DliFMkVTecLptsXaesuUHgL9dKIfvpm+rNXRn9wAwGjk0X/A== Message-ID: Date: Mon, 29 Oct 2018 18:48:15 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <87a7n37iuf.fsf@ashishki-desk.ger.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Mon, 29 Oct 2018 17:48:25 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/10/2018 12:13, Alexander Shishkin wrote: > Luwei Kang writes: > >> +static void pt_guest_enter(struct vcpu_vmx *vmx) >> +{ >> + if (pt_mode == PT_MODE_SYSTEM) >> + return; >> + >> + /* Save host state before VM entry */ >> + rdmsrl(MSR_IA32_RTIT_CTL, vmx->pt_desc.host.ctl); >> + >> + /* >> + * Set guest state of MSR_IA32_RTIT_CTL MSR (PT will be disabled >> + * on VM entry when it has been disabled in guest before). >> + */ >> + vmcs_write64(GUEST_IA32_RTIT_CTL, vmx->pt_desc.guest.ctl); >> + >> + if (vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN) { >> + wrmsrl(MSR_IA32_RTIT_CTL, 0); >> + pt_save_msr(&vmx->pt_desc.host, vmx->pt_desc.addr_range); >> + pt_load_msr(&vmx->pt_desc.guest, vmx->pt_desc.addr_range); >> + } >> +} > > From my side this is still a NAK, because [1]. > > [1] https://marc.info/?l=kvm&m=153847567226248&w=2 Then you should have replied to https://marc.info/?l=kvm&m=153865386015249&w=2 instead of having Luwei do the work for nothing. Quoting from there: >> One shouldn't have to enable or disable anything in KVM to stop it from >> breaking one's existing workflow. That makes no sense. > > If you "have to enable or disable anything" it means you have to > override the default. But the default in this patches is "no change > compared to before the patches", leaving tracing of both host and guest > entirely to the host, so I don't understand your remark. What workflow > is broken? > >> There already are controls in perf that enable/disable guest tracing. > > You are confusing "tracing guest from the host" and "the guest can trace > itself". This patchset is adding support for the latter, and that > affects directly whether the tracing CPUID leaf can be added to the > guest. Therefore it's not perf that can decide whether to turn it on; > KVM must know it when /dev/kvm is opened, which is why it is a module > parameter. I'd be happier if we found an agreement, but without discussion that just won't happen. Also, is there an existing interface to write a record into a tracing buffer? Paolo