From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42116) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1f0uUt-0008Tp-Oy for qemu-devel@nongnu.org; Tue, 27 Mar 2018 15:43:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1f0uUp-0006qX-5g for qemu-devel@nongnu.org; Tue, 27 Mar 2018 15:43:07 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:43728 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1f0uUp-0006px-0J for qemu-devel@nongnu.org; Tue, 27 Mar 2018 15:43:03 -0400 Date: Tue, 27 Mar 2018 22:42:56 +0300 From: "Michael S. Tsirkin" Message-ID: <20180327224058-mutt-send-email-mst@kernel.org> References: <1521211002-4529-1-git-send-email-wanpengli@tencent.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1521211002-4529-1-git-send-email-wanpengli@tencent.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] i386/kvm: add support for KVM_CAP_X86_DISABLE_EXITS List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Wanpeng Li Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, Paolo Bonzini , Radim =?utf-8?B?S3LEjW3DocWZ?= , Eduardo Habkost On Fri, Mar 16, 2018 at 07:36:42AM -0700, Wanpeng Li wrote: > From: Wanpeng Li >=20 > This patch adds support for KVM_CAP_X86_DISABLE_EXITS. Provides userspa= ce with=20 > per-VM capability(KVM_CAP_X86_DISABLE_EXITS) to not intercept MWAIT/HLT= /PAUSE=20 > in order that to improve latency in some workloads. >=20 > Cc: Paolo Bonzini > Cc: Radim Kr=C4=8Dm=C3=A1=C5=99 > Cc: Eduardo Habkost > Signed-off-by: Wanpeng Li > --- > linux-headers/linux/kvm.h | 6 +++++- > target/i386/kvm.c | 12 ++++++++++++ > 2 files changed, 17 insertions(+), 1 deletion(-) >=20 > diff --git a/linux-headers/linux/kvm.h b/linux-headers/linux/kvm.h > index a167be8..857df15 100644 > --- a/linux-headers/linux/kvm.h > +++ b/linux-headers/linux/kvm.h > @@ -925,7 +925,7 @@ struct kvm_ppc_resize_hpt { > #define KVM_CAP_S390_GS 140 > #define KVM_CAP_S390_AIS 141 > #define KVM_CAP_SPAPR_TCE_VFIO 142 > -#define KVM_CAP_X86_GUEST_MWAIT 143 > +#define KVM_CAP_X86_DISABLE_EXITS 143 > #define KVM_CAP_ARM_USER_IRQ 144 > #define KVM_CAP_S390_CMMA_MIGRATION 145 > #define KVM_CAP_PPC_FWNMI 146 > @@ -1508,6 +1508,10 @@ struct kvm_assigned_msix_entry { > #define KVM_X2APIC_API_USE_32BIT_IDS (1ULL << 0) > #define KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK (1ULL << 1) > =20 > +#define KVM_X86_DISABLE_EXITS_MWAIT (1 << 0) > +#define KVM_X86_DISABLE_EXITS_HLT (1 << 1) > +#define KVM_X86_DISABLE_EXITS_PAUSE (1 << 2) > + > /* Available with KVM_CAP_ARM_USER_IRQ */ > =20 > /* Bits for run->s.regs.device_irq_level */ > diff --git a/target/i386/kvm.c b/target/i386/kvm.c > index d23fff1..95ed9eb 100644 > --- a/target/i386/kvm.c > +++ b/target/i386/kvm.c > @@ -999,6 +999,18 @@ int kvm_arch_init_vcpu(CPUState *cs) > } > } > =20 > + if (env->features[FEAT_KVM_HINTS] & KVM_HINTS_DEDICATED) { > + int disable_exits =3D kvm_check_extension(cs->kvm_state, KVM_C= AP_X86_DISABLE_EXITS); > + if (disable_exits) { > + disable_exits &=3D (KVM_X86_DISABLE_EXITS_MWAIT | > + KVM_X86_DISABLE_EXITS_HLT | > + KVM_X86_DISABLE_EXITS_PAUSE); > + } > + if (kvm_vm_enable_cap(cs->kvm_state, KVM_CAP_X86_DISABLE_EXITS= , 0, disable_exits)) { > + error_report("kvm: DISABLE EXITS not supported"); > + } > + } > + > qemu_add_vm_change_state_handler(cpu_update_state, env); > =20 > c =3D cpuid_find_entry(&cpuid_data.cpuid, 1, 0); Why not a bit per capability? I can see how someone might want to disable mwait exists but not the rest of them. > --=20 > 2.7.4