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bh=Mqfkyc1h1IacAYuqVX+51EaEIUB4H7XAD3a00wXW0uo=; b=eir2d4PSGJ/MTPo0r1eSoM9O6N4VFKXDD1hvvAQaq/OmUvOjfL3JgzcKWqZpSR40TQT7/V 5yppdYlpv3eWQut0pgSUS19+d0zlLgr/xWEgnJWSREeoteqae9wbhQj0tjb/w/S8kP75vM bMwmT0WYEdaqlxMXrFzgYjfbt2Mq/fw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-129-NivpEGWfOKW2rqXDN2Iarw-1; Wed, 27 Oct 2021 11:18:33 -0400 X-MC-Unique: NivpEGWfOKW2rqXDN2Iarw-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 090521023F57; Wed, 27 Oct 2021 15:18:26 +0000 (UTC) Received: from starship (unknown [10.40.194.243]) by smtp.corp.redhat.com (Postfix) with ESMTP id 37C0260C48; Wed, 27 Oct 2021 15:18:14 +0000 (UTC) Message-ID: <796f9a7d553a0e13da5c44597666962620c64303.camel@redhat.com> Subject: Re: [PATCH v2 18/43] KVM: x86: Invoke kvm_vcpu_block() directly for non-HALTED wait states From: Maxim Levitsky To: Sean Christopherson , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Paul Mackerras , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Paolo Bonzini Cc: James Morse , Alexandru Elisei , Suzuki K Poulose , Atish Patra , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , Oliver Upton , Jing Zhang Date: Wed, 27 Oct 2021 18:18:13 +0300 In-Reply-To: <20211009021236.4122790-19-seanjc@google.com> References: <20211009021236.4122790-1-seanjc@google.com> <20211009021236.4122790-19-seanjc@google.com> User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211027_081838_099099_531FE45F X-CRM114-Status: GOOD ( 21.07 ) 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, 2021-10-08 at 19:12 -0700, Sean Christopherson wrote: > Call kvm_vcpu_block() directly for all wait states except HALTED so that > kvm_vcpu_halt() is no longer a misnomer on x86. > > Functionally, this means KVM will never attempt halt-polling or adjust > vcpu->halt_poll_ns for INIT_RECEIVED (a.k.a. Wait-For-SIPI (WFS)) or > AP_RESET_HOLD; UNINITIALIZED is handled in kvm_arch_vcpu_ioctl_run(), > and x86 doesn't use any other "wait" states. > > As mentioned above, the motivation of this is purely so that "halt" isn't > overloaded on x86, e.g. in KVM's stats. Skipping halt-polling for WFS > (and RESET_HOLD) has no meaningful effect on guest performance as there > are typically single-digit numbers of INIT-SIPI sequences per AP vCPU, > per boot, versus thousands of HLTs just to boot to console. > > Reviewed-by: David Matlack > Signed-off-by: Sean Christopherson > --- > arch/x86/kvm/x86.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index cd51f100e906..e0219acfd9cf 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -9899,7 +9899,10 @@ static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu) > if (!kvm_arch_vcpu_runnable(vcpu) && > (!kvm_x86_ops.pre_block || static_call(kvm_x86_pre_block)(vcpu) == 0)) { > srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); > - kvm_vcpu_halt(vcpu); > + if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED) > + kvm_vcpu_halt(vcpu); > + else > + kvm_vcpu_block(vcpu); > vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); > > if (kvm_x86_ops.post_block) Reviewed-by: Maxim Levitsky Best regards, Maxim Levitsky _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel