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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id n24sm7386923pgv.60.2021.08.27.10.23.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Aug 2021 10:23:09 -0700 (PDT) Date: Fri, 27 Aug 2021 17:23:05 +0000 From: Sean Christopherson To: Zhu Lingshan Subject: Re: [PATCH V10 01/18] perf/core: Use static_call to optimize perf_guest_info_callbacks Message-ID: References: <20210806133802.3528-1-lingshan.zhu@intel.com> <20210806133802.3528-2-lingshan.zhu@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210806133802.3528-2-lingshan.zhu@intel.com> X-Mailman-Approved-At: Fri, 27 Aug 2021 14:04:17 -0400 Cc: wanpengli@tencent.com, Like Xu , peterz@infradead.org, eranian@google.com, Guo Ren , linux-riscv@lists.infradead.org, Will Deacon , kvmarm@lists.cs.columbia.edu, kan.liang@linux.intel.com, ak@linux.intel.com, kvm@vger.kernel.org, Marc Zyngier , joro@8bytes.org, x86@kernel.org, linux-csky@vger.kernel.org, wei.w.wang@intel.com, linux-arm-kernel@lists.infradead.org, xen-devel@lists.xenproject.org, liuxiangdong5@huawei.com, bp@alien8.de, Paul Walmsley , Boris Ostrovsky , boris.ostrvsky@oracle.com, jmattson@google.com, like.xu.linux@gmail.com, Nick Hu , linux-kernel@vger.kernel.org, pbonzini@redhat.com, vkuznets@redhat.com X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Fri, Aug 06, 2021, Zhu Lingshan wrote: > @@ -2944,18 +2966,21 @@ static unsigned long code_segment_base(struct pt_regs *regs) > > unsigned long perf_instruction_pointer(struct pt_regs *regs) > { > - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) > - return perf_guest_cbs->get_guest_ip(); > + unsigned long ip = static_call(x86_guest_get_ip)(); > + > + if (likely(!ip)) Pivoting on ip==0 isn't correct, it's perfectly legal for a guest to execute from %rip=0. Unless there's some static_call() magic that supports this with a default function: if (unlikely(!static_call(x86_guest_get_ip)(&ip))) regs->ip + code_segment_base(regs) return ip; The easiest thing is keep the existing: if (unlikely(static_call(x86_guest_state)())) return static_call(x86_guest_get_ip)(); return regs->ip + code_segment_base(regs); It's an extra call for PMIs in guest, but I don't think any of the KVM folks care _that_ much about the performance in this case. > + ip = regs->ip + code_segment_base(regs); > > - return regs->ip + code_segment_base(regs); > + return ip; > } _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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=-18.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 9EB16C4320E for ; Fri, 27 Aug 2021 17:23:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D94060E0B for ; Fri, 27 Aug 2021 17:23:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237288AbhH0RYd (ORCPT ); Fri, 27 Aug 2021 13:24:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32824 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343493AbhH0RYW (ORCPT ); Fri, 27 Aug 2021 13:24:22 -0400 Received: from mail-pf1-x431.google.com (mail-pf1-x431.google.com [IPv6:2607:f8b0:4864:20::431]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B6A02C0612A4 for ; Fri, 27 Aug 2021 10:23:10 -0700 (PDT) Received: by mail-pf1-x431.google.com with SMTP id m26so6272149pff.3 for ; Fri, 27 Aug 2021 10:23:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=pW2KRXINIECq2UqrMAjVuApe68m2StZHA9v7va6qTiU=; b=rYBmoVs975N+yu2934Kl7Ag8dNi2tkW5MPQBPsQWMJceqaAUViMJX5p8VTsmrLat2L 1kJT1N4rNPJvHYN4v8xV4LZQQiN0gVYVxxZoK0AWZMQtgbtlsholocVLBSLsdQUjTc7K EO/n6pcBnNhyHknntLRnjl3c7dPZnYup1ZY4k8dYXcB6+XwMELnSDRN8GScTXVD9wLYw 72HE/X1LKTlO7T9MyRzf3/jBybVrYz/zMXfVi26QTtQIvfOSsE3Kyet1JW3IoRhxG7Z4 s9RsOEhsC/QREunQ94/foNgn4vxgTRk3Re13QZxXDPqu5Xx6dQ43rKJdU90h8PsbIabZ TDVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=pW2KRXINIECq2UqrMAjVuApe68m2StZHA9v7va6qTiU=; b=Gsa2qvQYkGx2769FBORCA4oRPOZEp0NIDfNEme7xWIrerisFcDptZ5FnuyRliGUxbK rzBe3rRWaY2UqtVQ5nDKqLhDKN3nYp9FG9ZIGQ9AyOO+1PteKuxJWrsW/U5HynIfOM/G mK0YsDUsmfFNkVpER7A2A1VLNoD6Okf23tHjqZSYNbQMwcF6yVgSET5APQ2c5kvDekt4 8Jh00ehbmEpBOt26Pyak64brhVwbhyYPTD2xUmjHhJOhrjaLe8gMUqyQKYrUdNGj3YHS SIBtQbVBNCJKo0/NV8ykFEEhU0AUOYNnz4OKHfN08BlPLA1MbRAEP53Qk9iw7Gt0hklc JsaA== X-Gm-Message-State: AOAM530EDGoWBdgW1MPYirBnSpZcGJk/JUn+B/cdHSwvmXrAS1h9bM/j MjDVEenLKH+4QE6M5ltRFyZGcQ== X-Google-Smtp-Source: ABdhPJz+T5dgH3sIVem/Dht2xu+EGET8qPyEg43yvrgPII1mSQTEgb7AA1JRyZkdBQMuVGObTA+XjQ== X-Received: by 2002:a63:ef14:: with SMTP id u20mr8773852pgh.13.1630084990019; Fri, 27 Aug 2021 10:23:10 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id n24sm7386923pgv.60.2021.08.27.10.23.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Aug 2021 10:23:09 -0700 (PDT) Date: Fri, 27 Aug 2021 17:23:05 +0000 From: Sean Christopherson To: Zhu Lingshan Cc: peterz@infradead.org, pbonzini@redhat.com, bp@alien8.de, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, kan.liang@linux.intel.com, ak@linux.intel.com, wei.w.wang@intel.com, eranian@google.com, liuxiangdong5@huawei.com, linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org, like.xu.linux@gmail.com, boris.ostrvsky@oracle.com, Like Xu , Will Deacon , Marc Zyngier , Guo Ren , Nick Hu , Paul Walmsley , Boris Ostrovsky , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, xen-devel@lists.xenproject.org Subject: Re: [PATCH V10 01/18] perf/core: Use static_call to optimize perf_guest_info_callbacks Message-ID: References: <20210806133802.3528-1-lingshan.zhu@intel.com> <20210806133802.3528-2-lingshan.zhu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210806133802.3528-2-lingshan.zhu@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-csky@vger.kernel.org On Fri, Aug 06, 2021, Zhu Lingshan wrote: > @@ -2944,18 +2966,21 @@ static unsigned long code_segment_base(struct pt_regs *regs) > > unsigned long perf_instruction_pointer(struct pt_regs *regs) > { > - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) > - return perf_guest_cbs->get_guest_ip(); > + unsigned long ip = static_call(x86_guest_get_ip)(); > + > + if (likely(!ip)) Pivoting on ip==0 isn't correct, it's perfectly legal for a guest to execute from %rip=0. Unless there's some static_call() magic that supports this with a default function: if (unlikely(!static_call(x86_guest_get_ip)(&ip))) regs->ip + code_segment_base(regs) return ip; The easiest thing is keep the existing: if (unlikely(static_call(x86_guest_state)())) return static_call(x86_guest_get_ip)(); return regs->ip + code_segment_base(regs); It's an extra call for PMIs in guest, but I don't think any of the KVM folks care _that_ much about the performance in this case. > + ip = regs->ip + code_segment_base(regs); > > - return regs->ip + code_segment_base(regs); > + return ip; > } 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=-9.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 D4BFDC432BE for ; Fri, 27 Aug 2021 17:23:27 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9684360FD9 for ; Fri, 27 Aug 2021 17:23:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 9684360FD9 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=G3Zt5YOC+3wp1eKbYf4Aghw2xMLYilfRmhBXT/CcB0Q=; b=g27xT+PT6a0z6Q NqxkQ3f8cmAOaeFEMSGE18j6UQGsICbf8OIDJlRt7ec5UX0hmcQ4RK040tq68pHR06BayS9EnZk2w WfI7tBD9HTbbH1VHoNI4wH59MUeDmgfYwxIGLYZZeswl9y7PbSeftIMwlM/IKRRp53at+lldMdl4b WIVc1nuJdi6iTd64MDkCipiUYIje+2ZAzMgXsn0fU2VUJPFQ0xx6RLseA5joaOc0dDxj2SHcy+srX bnsJHDQ0ZwxdktbuSHSz0199yrGjcqsLfBDhyWV2Afr+avC48PpsTClYIwKLLZydKFsBN2rWc/kdn SOMmCc9+/UU8U+ZHCz5Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mJfZS-00CsaD-9S; Fri, 27 Aug 2021 17:23:14 +0000 Received: from mail-pf1-x436.google.com ([2607:f8b0:4864:20::436]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mJfZP-00CsXw-8j for linux-riscv@lists.infradead.org; Fri, 27 Aug 2021 17:23:12 +0000 Received: by mail-pf1-x436.google.com with SMTP id u6so5615504pfi.0 for ; Fri, 27 Aug 2021 10:23:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=pW2KRXINIECq2UqrMAjVuApe68m2StZHA9v7va6qTiU=; b=rYBmoVs975N+yu2934Kl7Ag8dNi2tkW5MPQBPsQWMJceqaAUViMJX5p8VTsmrLat2L 1kJT1N4rNPJvHYN4v8xV4LZQQiN0gVYVxxZoK0AWZMQtgbtlsholocVLBSLsdQUjTc7K EO/n6pcBnNhyHknntLRnjl3c7dPZnYup1ZY4k8dYXcB6+XwMELnSDRN8GScTXVD9wLYw 72HE/X1LKTlO7T9MyRzf3/jBybVrYz/zMXfVi26QTtQIvfOSsE3Kyet1JW3IoRhxG7Z4 s9RsOEhsC/QREunQ94/foNgn4vxgTRk3Re13QZxXDPqu5Xx6dQ43rKJdU90h8PsbIabZ TDVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=pW2KRXINIECq2UqrMAjVuApe68m2StZHA9v7va6qTiU=; b=ckhQlrbbucIQEVZOIQt4ujtFTC5EIdtw9e0WzkS5p0iFbClM8xSnV8f52tp3UwRW4t u7smxj0zoD34oCvTYKhXsVBTGl/adwk0Gu7zSi5CGGwr9anEUU3SN/5sx+JqQzFydQSW qYi+eKsw449PUGeGMXJ5w/6LwO9YsttGTFo5V5bXD4znB4vnMMMiNlA33jRsviUrFI9c f9z+FD6Th3v8TgwIg8/vNG2NIIWd98HlsAzMYUKBS8DINo+XvJ7GUhunz5UZqeaIyXTa pwjIcgugAiKkAb9R1mNbrpr8BYzsqwJBL1IyOQyJH+haXgWLDY5dhYBEibxO2YIRKz7O IatA== X-Gm-Message-State: AOAM532GbL2HQ3SwSbHjtqrw88p9TnEMeZ/aH6ofxYsEC1TvdDLDyCEO 1k/T34fglijx+mVQds1xQSqp4Q== X-Google-Smtp-Source: ABdhPJz+T5dgH3sIVem/Dht2xu+EGET8qPyEg43yvrgPII1mSQTEgb7AA1JRyZkdBQMuVGObTA+XjQ== X-Received: by 2002:a63:ef14:: with SMTP id u20mr8773852pgh.13.1630084990019; Fri, 27 Aug 2021 10:23:10 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id n24sm7386923pgv.60.2021.08.27.10.23.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Aug 2021 10:23:09 -0700 (PDT) Date: Fri, 27 Aug 2021 17:23:05 +0000 From: Sean Christopherson To: Zhu Lingshan Cc: peterz@infradead.org, pbonzini@redhat.com, bp@alien8.de, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, kan.liang@linux.intel.com, ak@linux.intel.com, wei.w.wang@intel.com, eranian@google.com, liuxiangdong5@huawei.com, linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org, like.xu.linux@gmail.com, boris.ostrvsky@oracle.com, Like Xu , Will Deacon , Marc Zyngier , Guo Ren , Nick Hu , Paul Walmsley , Boris Ostrovsky , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, xen-devel@lists.xenproject.org Subject: Re: [PATCH V10 01/18] perf/core: Use static_call to optimize perf_guest_info_callbacks Message-ID: References: <20210806133802.3528-1-lingshan.zhu@intel.com> <20210806133802.3528-2-lingshan.zhu@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210806133802.3528-2-lingshan.zhu@intel.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210827_102311_327150_EFE55AC6 X-CRM114-Status: GOOD ( 10.87 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Fri, Aug 06, 2021, Zhu Lingshan wrote: > @@ -2944,18 +2966,21 @@ static unsigned long code_segment_base(struct pt_regs *regs) > > unsigned long perf_instruction_pointer(struct pt_regs *regs) > { > - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) > - return perf_guest_cbs->get_guest_ip(); > + unsigned long ip = static_call(x86_guest_get_ip)(); > + > + if (likely(!ip)) Pivoting on ip==0 isn't correct, it's perfectly legal for a guest to execute from %rip=0. Unless there's some static_call() magic that supports this with a default function: if (unlikely(!static_call(x86_guest_get_ip)(&ip))) regs->ip + code_segment_base(regs) return ip; The easiest thing is keep the existing: if (unlikely(static_call(x86_guest_state)())) return static_call(x86_guest_get_ip)(); return regs->ip + code_segment_base(regs); It's an extra call for PMIs in guest, but I don't think any of the KVM folks care _that_ much about the performance in this case. > + ip = regs->ip + code_segment_base(regs); > > - return regs->ip + code_segment_base(regs); > + return ip; > } _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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=-9.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_ADSP_CUSTOM_MED,DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 592E6C432BE for ; Fri, 27 Aug 2021 17:24:47 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 19B0660EB5 for ; Fri, 27 Aug 2021 17:24:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 19B0660EB5 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=g96v2pz3wj8h8LkKApIJam+pLq12mKBlD9Ae3r8xQM0=; b=txRoxjXTfxiwQu 7TX5/8pBGdPExRZJ6Tsj9iDxRCMBcoAXIPMlaZQGmjtSx3/Y8wEvu6UyvthPbuJtm1Lj394qWcGeR 78siBaGMEDJdkLb9L4VeSa3YIUfvkAkEeEcHZzz6rwz9FFvnfh5+PfswyDa9ZLcQxJM1r5ysHKpF8 wdROPpxSUeNJj8gCrAz4ujxnTdlKfWnHJchA6lMQWMjw+li5xZrEcGOnk/M+EsBxzZl4T7HVmoMer rXzgqjH7Z3mIKKlI+B3tdJ5Ll1YrStGW03yRx0X5f5rGT2p7OHCRHpxsEjeNYe6qkJD5IXrFee+cd YWaXdj3GLboSppEFmjAA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mJfZV-00CsaX-8z; Fri, 27 Aug 2021 17:23:17 +0000 Received: from mail-pg1-x529.google.com ([2607:f8b0:4864:20::529]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mJfZP-00CsXy-Ce for linux-arm-kernel@lists.infradead.org; Fri, 27 Aug 2021 17:23:13 +0000 Received: by mail-pg1-x529.google.com with SMTP id 17so6508257pgp.4 for ; Fri, 27 Aug 2021 10:23:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=pW2KRXINIECq2UqrMAjVuApe68m2StZHA9v7va6qTiU=; b=rYBmoVs975N+yu2934Kl7Ag8dNi2tkW5MPQBPsQWMJceqaAUViMJX5p8VTsmrLat2L 1kJT1N4rNPJvHYN4v8xV4LZQQiN0gVYVxxZoK0AWZMQtgbtlsholocVLBSLsdQUjTc7K EO/n6pcBnNhyHknntLRnjl3c7dPZnYup1ZY4k8dYXcB6+XwMELnSDRN8GScTXVD9wLYw 72HE/X1LKTlO7T9MyRzf3/jBybVrYz/zMXfVi26QTtQIvfOSsE3Kyet1JW3IoRhxG7Z4 s9RsOEhsC/QREunQ94/foNgn4vxgTRk3Re13QZxXDPqu5Xx6dQ43rKJdU90h8PsbIabZ TDVA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=pW2KRXINIECq2UqrMAjVuApe68m2StZHA9v7va6qTiU=; b=CddD033k5N/mFcJcWvWZMD2mzLF0yM/MmL4zc+HggJIrwtC+2ZvB2IV59xFFOpNgcu ZSnKHpkxKN6/p/xqHlFF18wdHu0jVrBkRTPGUQxsVG94dTdy6P2j2vYmSzDzhko+7xvz BJQzbrgCPbIFWrqeILHcOqJgXIpkM8VMAO8XCoTdSZYDLDYBxJdEpi/PlsEz16dKv86K /8peoVxwSBJmwgxLsDaoT4YRHK5cim+3irdteztgYF3NKMYAPi0f3AaFViTIZpBlqenq 0s1UcX9IAjf6rx5e20dnWyIRW+2XNSQTtnuC5GGW0T7YUaK2iIa4OvSCav1xK9jojxJ8 20tA== X-Gm-Message-State: AOAM5300d3gVkxmnEH4p9q648OB9wPsA5KY1gwLx2mrFeiEOqEtlQiWa GrZOICrs2+wvelg31fwdiXXfcA== X-Google-Smtp-Source: ABdhPJz+T5dgH3sIVem/Dht2xu+EGET8qPyEg43yvrgPII1mSQTEgb7AA1JRyZkdBQMuVGObTA+XjQ== X-Received: by 2002:a63:ef14:: with SMTP id u20mr8773852pgh.13.1630084990019; Fri, 27 Aug 2021 10:23:10 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id n24sm7386923pgv.60.2021.08.27.10.23.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Aug 2021 10:23:09 -0700 (PDT) Date: Fri, 27 Aug 2021 17:23:05 +0000 From: Sean Christopherson To: Zhu Lingshan Cc: peterz@infradead.org, pbonzini@redhat.com, bp@alien8.de, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, kan.liang@linux.intel.com, ak@linux.intel.com, wei.w.wang@intel.com, eranian@google.com, liuxiangdong5@huawei.com, linux-kernel@vger.kernel.org, x86@kernel.org, kvm@vger.kernel.org, like.xu.linux@gmail.com, boris.ostrvsky@oracle.com, Like Xu , Will Deacon , Marc Zyngier , Guo Ren , Nick Hu , Paul Walmsley , Boris Ostrovsky , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-csky@vger.kernel.org, linux-riscv@lists.infradead.org, xen-devel@lists.xenproject.org Subject: Re: [PATCH V10 01/18] perf/core: Use static_call to optimize perf_guest_info_callbacks Message-ID: References: <20210806133802.3528-1-lingshan.zhu@intel.com> <20210806133802.3528-2-lingshan.zhu@intel.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210806133802.3528-2-lingshan.zhu@intel.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210827_102311_461364_3F591C2C X-CRM114-Status: GOOD ( 12.38 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Aug 06, 2021, Zhu Lingshan wrote: > @@ -2944,18 +2966,21 @@ static unsigned long code_segment_base(struct pt_regs *regs) > > unsigned long perf_instruction_pointer(struct pt_regs *regs) > { > - if (perf_guest_cbs && perf_guest_cbs->is_in_guest()) > - return perf_guest_cbs->get_guest_ip(); > + unsigned long ip = static_call(x86_guest_get_ip)(); > + > + if (likely(!ip)) Pivoting on ip==0 isn't correct, it's perfectly legal for a guest to execute from %rip=0. Unless there's some static_call() magic that supports this with a default function: if (unlikely(!static_call(x86_guest_get_ip)(&ip))) regs->ip + code_segment_base(regs) return ip; The easiest thing is keep the existing: if (unlikely(static_call(x86_guest_state)())) return static_call(x86_guest_get_ip)(); return regs->ip + code_segment_base(regs); It's an extra call for PMIs in guest, but I don't think any of the KVM folks care _that_ much about the performance in this case. > + ip = regs->ip + code_segment_base(regs); > > - return regs->ip + code_segment_base(regs); > + return ip; > } _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel