From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:33476) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ek84k-0003gB-86 for qemu-devel@nongnu.org; Fri, 09 Feb 2018 07:46:47 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ek84f-000884-Mz for qemu-devel@nongnu.org; Fri, 09 Feb 2018 07:46:46 -0500 Received: from mx1.redhat.com ([209.132.183.28]:42394) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1ek84f-00087Y-Dl for qemu-devel@nongnu.org; Fri, 09 Feb 2018 07:46:41 -0500 Date: Fri, 9 Feb 2018 10:46:38 -0200 From: Eduardo Habkost 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-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Qemu-devel] [PATCH] target-i386: adds PV_DEDICATED hint CPUID feature bit List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wanpeng Li Cc: Paolo Bonzini , "qemu-devel@nongnu.org Developers" , kvm , Radim =?utf-8?B?S3LEjW3DocWZ?= 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/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); > > 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 -- Eduardo