From patchwork Fri Sep 20 21:25:09 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrea Arcangeli X-Patchwork-Id: 11154875 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id CCE671599 for ; Fri, 20 Sep 2019 21:26:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA3B420820 for ; Fri, 20 Sep 2019 21:26:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393915AbfITV0C (ORCPT ); Fri, 20 Sep 2019 17:26:02 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57988 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2393779AbfITVZO (ORCPT ); Fri, 20 Sep 2019 17:25:14 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 10B208980EA; Fri, 20 Sep 2019 21:25:14 +0000 (UTC) Received: from mail (ovpn-120-159.rdu2.redhat.com [10.10.120.159]) by smtp.corp.redhat.com (Postfix) with ESMTPS id E76295D6B2; Fri, 20 Sep 2019 21:25:13 +0000 (UTC) From: Andrea Arcangeli To: Paolo Bonzini Cc: Vitaly Kuznetsov , "Dr. David Alan Gilbert" , Marcelo Tosatti , Peter Xu , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 17/17] x86: retpolines: eliminate retpoline from msr event handlers Date: Fri, 20 Sep 2019 17:25:09 -0400 Message-Id: <20190920212509.2578-18-aarcange@redhat.com> In-Reply-To: <20190920212509.2578-1-aarcange@redhat.com> References: <20190920212509.2578-1-aarcange@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.67]); Fri, 20 Sep 2019 21:25:14 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org It's enough to check the value and issue the direct call. After this commit is applied, here the most common retpolines executed under a high resolution timer workload in the guest on a VMX host: [..] @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 267 @[]: 2256 @[ trace_retpoline+1 __trace_retpoline+30 __x86_indirect_thunk_rax+33 __kvm_wait_lapic_expire+284 vmx_vcpu_run.part.97+1091 vcpu_enter_guest+377 kvm_arch_vcpu_ioctl_run+261 kvm_vcpu_ioctl+559 do_vfs_ioctl+164 ksys_ioctl+96 __x64_sys_ioctl+22 do_syscall_64+89 entry_SYSCALL_64_after_hwframe+68 ]: 2390 @[]: 33410 @total: 315707 Note the highest hit above is __delay so probably not worth optimizing even if it would be more frequent than 2k hits per sec. Signed-off-by: Andrea Arcangeli --- arch/x86/events/intel/core.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 27ee47a7be66..65b383d5e062 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3323,8 +3323,19 @@ static int intel_pmu_hw_config(struct perf_event *event) return 0; } +#ifdef CONFIG_RETPOLINE +static struct perf_guest_switch_msr *core_guest_get_msrs(int *nr); +static struct perf_guest_switch_msr *intel_guest_get_msrs(int *nr); +#endif + struct perf_guest_switch_msr *perf_guest_get_msrs(int *nr) { +#ifdef CONFIG_RETPOLINE + if (x86_pmu.guest_get_msrs == intel_guest_get_msrs) + return intel_guest_get_msrs(nr); + else if (x86_pmu.guest_get_msrs == core_guest_get_msrs) + return core_guest_get_msrs(nr); +#endif if (x86_pmu.guest_get_msrs) return x86_pmu.guest_get_msrs(nr); *nr = 0;