From patchwork Fri Feb 9 12:46:38 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eduardo Habkost X-Patchwork-Id: 10208935 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id EB6B260236 for ; Fri, 9 Feb 2018 12:46:44 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E071529845 for ; Fri, 9 Feb 2018 12:46:44 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D541C29847; Fri, 9 Feb 2018 12:46:44 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2A3A829846 for ; Fri, 9 Feb 2018 12:46:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752086AbeBIMql (ORCPT ); Fri, 9 Feb 2018 07:46:41 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45624 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752028AbeBIMqk (ORCPT ); Fri, 9 Feb 2018 07:46:40 -0500 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 1AD7C83F75; Fri, 9 Feb 2018 12:46:40 +0000 (UTC) Received: from localhost (ovpn-116-12.gru2.redhat.com [10.97.116.12]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5A1305EE1C; Fri, 9 Feb 2018 12:46:39 +0000 (UTC) Date: Fri, 9 Feb 2018 10:46:38 -0200 From: Eduardo Habkost To: Wanpeng Li Cc: Paolo Bonzini , "qemu-devel@nongnu.org Developers" , kvm , Radim =?utf-8?B?S3LEjW3DocWZ?= Subject: Re: [PATCH] target-i386: adds PV_DEDICATED hint CPUID feature bit Message-ID: <20180209124638.GH13981@localhost.localdomain> References: <1518083060-5881-1-git-send-email-wanpengli@tencent.com> <20180208181207.GB13981@localhost.localdomain> <20180209114615.GG13981@localhost.localdomain> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-Fnord: you can see the fnord User-Agent: Mutt/1.9.1 (2017-09-22) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Fri, 09 Feb 2018 12:46:40 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On Fri, Feb 09, 2018 at 08:24:26PM +0800, Wanpeng Li wrote: > 2018-02-09 19:46 GMT+08:00 Eduardo Habkost : > > On Fri, Feb 09, 2018 at 09:41:41AM +0100, Paolo Bonzini wrote: > >> On 08/02/2018 19:12, Eduardo Habkost wrote: > >> > On Thu, Feb 08, 2018 at 05:44:20PM +0800, Wanpeng Li wrote: > >> >> From: Wanpeng Li > >> >> > >> >> Add PV_DEDICATED hint cpuid feature bit. > >> >> > >> > [...] > >> >> diff --git a/target/i386/cpu.c b/target/i386/cpu.c > >> >> index d70954b..cf48931 100644 > >> >> --- a/target/i386/cpu.c > >> >> +++ b/target/i386/cpu.c > >> >> @@ -4076,6 +4076,9 @@ static int x86_cpu_filter_features(X86CPU *cpu) > >> >> x86_cpu_get_supported_feature_word(w, false); > >> >> uint32_t requested_features = env->features[w]; > >> >> env->features[w] &= host_feat; > >> >> + if (cpu->pv_dedicated && (w == FEAT_KVM)) { > >> >> + env->features[w] |= CPUID_PV_DEDICATED; > >> >> + } > >> > > >> > Why do this trick here instead of just adding "pv-dedicated" to > >> > feature_word_info[FEAT_KVM].feat_names? > >> > >> I think because it can be added independent of KVM_GET_SUPPORTED_CPUID. > > > > If QEMU knows it can be enabled if outside GET_SUPPORTED_CPUID, > > kvm_arch_get_supported_cpuid() can return it as supported. > > The guest fails to detect the new cpuid this time. This should fix it: > > diff --git a/target/i386/cpu.c b/target/i386/cpu.c > index d70954b..e2974ad 100644 > --- a/target/i386/cpu.c > +++ b/target/i386/cpu.c > @@ -358,6 +358,20 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = { > .cpuid_eax = KVM_CPUID_FEATURES, .cpuid_reg = R_EAX, > .tcg_features = TCG_KVM_FEATURES, > }, > + [FEAT_KVM_HINTS] = { > + .feat_names = { > + "hint-dedicated", NULL, NULL, NULL, > + NULL, NULL, NULL, NULL, > + NULL, NULL, NULL, NULL, > + NULL, NULL, NULL, NULL, > + NULL, NULL, NULL, NULL, > + NULL, NULL, NULL, NULL, > + NULL, NULL, NULL, NULL, > + NULL, NULL, NULL, NULL, > + }, > + .cpuid_eax = KVM_CPUID_FEATURES, .cpuid_reg = R_EDX, > + .tcg_features = TCG_KVM_FEATURES, > + }, > [FEAT_HYPERV_EAX] = { > .feat_names = { > NULL /* hv_msr_vp_runtime_access */, NULL /* > hv_msr_time_refcount_access */, > diff --git a/target/i386/cpu.h b/target/i386/cpu.h > index f91e37d..9f73692 100644 > --- a/target/i386/cpu.h > +++ b/target/i386/cpu.h > @@ -475,6 +475,7 @@ typedef enum FeatureWord { > FEAT_8000_0008_EBX, /* CPUID[8000_0008].EBX */ > FEAT_C000_0001_EDX, /* CPUID[C000_0001].EDX */ > FEAT_KVM, /* CPUID[4000_0001].EAX (KVM_CPUID_FEATURES) */ > + FEAT_KVM_HINTS, /* CPUID[4000_0001].EDX */ > FEAT_HYPERV_EAX, /* CPUID[4000_0003].EAX */ > FEAT_HYPERV_EBX, /* CPUID[4000_0003].EBX */ > FEAT_HYPERV_EDX, /* CPUID[4000_0003].EDX */ > @@ -670,6 +671,8 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS]; > #define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply > Accumulation Single Precision */ > #define CPUID_7_0_EDX_SPEC_CTRL (1U << 26) /* Speculation Control */ > > +#define KVM_HINTS_DEDICATED (1U << 0) > + > #define CPUID_8000_0008_EBX_IBPB (1U << 12) /* Indirect Branch > Prediction Barrier */ > > #define CPUID_XSAVE_XSAVEOPT (1U << 0) > diff --git a/target/i386/kvm.c b/target/i386/kvm.c > index ad4b159..a0aad80 100644 > --- a/target/i386/kvm.c > +++ b/target/i386/kvm.c > @@ -383,6 +383,9 @@ uint32_t kvm_arch_get_supported_cpuid(KVMState *s, > uint32_t function, > if (!kvm_irqchip_in_kernel()) { > ret &= ~(1U << KVM_FEATURE_PV_UNHALT); > } > + } else if (function == KVM_CPUID_FEATURES && reg == R_EDX) { > + ret |= KVM_HINTS_DEDICATED; > + found = 1; > } > > /* fallback for older kernels */ > > > Regards, > Wanpeng Li diff --git a/target/i386/kvm.c b/target/i386/kvm.c index a0aad808bd..44ee524188 100644 --- a/target/i386/kvm.c +++ b/target/i386/kvm.c @@ -804,6 +804,7 @@ int kvm_arch_init_vcpu(CPUState *cs) c = &cpuid_data.entries[cpuid_i++]; c->function = KVM_CPUID_FEATURES | kvm_base; c->eax = env->features[FEAT_KVM]; + c->edx = env->features[FEAT_KVM_HINTS]; } cpu_x86_cpuid(env, 0, 0, &limit, &unused, &unused, &unused);