Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935428AbeAORbU (ORCPT + 1 other); Mon, 15 Jan 2018 12:31:20 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43276 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933233AbeAORbR (ORCPT ); Mon, 15 Jan 2018 12:31:17 -0500 From: Vitaly Kuznetsov To: kvm@vger.kernel.org Cc: x86@kernel.org, Paolo Bonzini , =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , "Michael Kelley (EOSG)" , Mohammed Gamal , Cathy Avery , Bandan Das , linux-kernel@vger.kernel.org Subject: [RFC 0/6] Enlightened VMCS support for KVM on Hyper-V Date: Mon, 15 Jan 2018 18:30:59 +0100 Message-Id: <20180115173105.31845-1-vkuznets@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Mon, 15 Jan 2018 17:31:12 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: Early RFC. I'll refer to this patchset in my DevConf/FOSDEM presentations. When running nested KVM on Hyper-V it's possible to use so called 'Enlightened VMCS' and do normal memory reads/writes instead of doing VMWRITE/VMREAD instructions. Tests show that this speeds up tight CPUID loop almost 3 times: Before: ./cpuid_tight 20459 After: ./cpuid_tight 7698 checkpatch.pl errors/warnings and possible 32bit brokenness are known things. Main RFC questions I have are: - Do we want to have this per L2 VM or per L1 host? - How can we achieve zero overhead for non-Hyper-V deployments? Use static keys? But this will only work if we decide to do eVMCS per host. - Can we do better than a big switch in evmcs_read()/evmcs_write()? And probably don't use 'case' defines which checkpatch.pl hates. I would really apreciate any feedback! Ladi Prosek (1): x86/kvm: rename HV_X64_MSR_APIC_ASSIST_PAGE to HV_X64_MSR_VP_ASSIST_PAGE Vitaly Kuznetsov (5): x86/hyper-v: define virtual processor assist page structure x86/hyper-v: allocate and use hv_vp_assist_pages x86/hyper-v: define struct hv_enlightened_vmcs and clean field bits x86/hyper-v: detect nested features x86/kvm: use enlightened VMCS when running on Hyper-V arch/x86/hyperv/hv_init.c | 35 ++- arch/x86/include/asm/mshyperv.h | 3 + arch/x86/include/uapi/asm/hyperv.h | 223 +++++++++++++- arch/x86/kernel/cpu/mshyperv.c | 3 + arch/x86/kvm/hyperv.c | 8 +- arch/x86/kvm/lapic.h | 2 +- arch/x86/kvm/vmx.c | 595 ++++++++++++++++++++++++++++++++++++- arch/x86/kvm/x86.c | 2 +- 8 files changed, 857 insertions(+), 14 deletions(-) -- 2.14.3