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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=qMKgtBgwBs2NQxoA+pqhzkcW4VxhWNcSOwckUHcRIvs=; b=bGVcdQmZUS76Xo+nNolNocm39M4iXGJaKybcC3MtucFPT+SIVWKRQ30TxjHSptSXA8 jEtVhmc5mggK/jllv/VhVqRJn/MixXvcl3s9NEYu79CLwgHtRS7e6n7rf24cwykXyrXJ PcTylfqBKRFhJVZJK5rOSbt/4ytMBQyJZRBISVh1HO8RJO71az8dOoJXbLmTlRfmsU3n mZs2gFICZTVoG6P9HohBSRD+y3QKc1sJC8bc+4jZlS3T7qOPyAHhC+FgdocBcRXITHNn WHgjBA+i+lOvvHz8ilXnNJZWGAXEDHTftGw78WxeQH9r0/iRGMkFUk6RcbwhNXiSXTZP U1Lw== X-Gm-Message-State: APt69E27USB1so81en4FlnH92iswknlZSqqjvtgdxKN3wsq70H9AyERv pMrZmCpTcKdfoyLCYZqf5waWwHMbQOAKqliH5JE= X-Google-Smtp-Source: AAOMgpcTywQ2vaa5+dFMqjhHGyqdi19jStc3w3fXSKYxfrnUyB69YDl90+5L3TVptPlmNMGwCnS0XVQh1qgnDqGnJls= X-Received: by 2002:aca:ad4f:: with SMTP id w76-v6mr2808000oie.233.1530353099248; Sat, 30 Jun 2018 03:04:59 -0700 (PDT) MIME-Version: 1.0 References: <1530265876-18136-1-git-send-email-wanpengli@tencent.com> <1530265876-18136-3-git-send-email-wanpengli@tencent.com> <96bad133-077d-e27d-9f57-4df6399eb3b8@redhat.com> In-Reply-To: <96bad133-077d-e27d-9f57-4df6399eb3b8@redhat.com> From: Wanpeng Li Date: Sat, 30 Jun 2018 18:04:47 +0800 Message-ID: Subject: Re: [PATCH 2/2] KVM: X86: Implement PV send IPI support To: Paolo Bonzini Cc: LKML , kvm , Radim Krcmar , Vitaly Kuznetsov Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 29 Jun 2018 at 18:45, Paolo Bonzini wrote: > > On 29/06/2018 11:51, Wanpeng Li wrote: > > From: Wanpeng Li > > > > Using hypercall to send IPIs by one vmexit instead of one by one for > > xAPIC/x2APIC physical mode and one vmexit per-cluster for x2APIC cluste= r > > mode. > > > > Even if enable qemu interrupt remapping and PV TLB Shootdown, I can sti= ll > > observe ~14% performance boost by ebizzy benchmark for 64 vCPUs VM, the > > total msr-induced vmexits reduce ~70%. > > > > Cc: Paolo Bonzini > > Cc: Radim Kr=C4=8Dm=C3=A1=C5=99 > > Cc: Vitaly Kuznetsov > > Signed-off-by: Wanpeng Li > > --- > > Documentation/virtual/kvm/cpuid.txt | 4 ++++ > > arch/x86/kvm/cpuid.c | 3 ++- > > arch/x86/kvm/x86.c | 25 +++++++++++++++++++++++++ > > include/uapi/linux/kvm_para.h | 1 + > > 4 files changed, 32 insertions(+), 1 deletion(-) > > > > diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtua= l/kvm/cpuid.txt > > index ab022dc..d72359f 100644 > > --- a/Documentation/virtual/kvm/cpuid.txt > > +++ b/Documentation/virtual/kvm/cpuid.txt > > @@ -62,6 +62,10 @@ KVM_FEATURE_ASYNC_PF_VMEXIT || 10 || parav= irtualized async PF VM exit > > || || can be enabled by setti= ng bit 2 > > || || when writing to msr 0x4= b564d02 > > ----------------------------------------------------------------------= -------- > > +KVM_FEATURE_PV_SEND_IPI || 11 || guest checks this featu= re bit > > + || || before enabling paravir= tualized > > + || || send IPIs. > > It's not "enabling" but "using". You also need to document the > hypercall itself. Will fix it in v2. Regards, Wanpeng Li