From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: [PATCH 0/5] Lazy fpu, cr0.ts Date: Wed, 30 Dec 2009 18:25:37 +0200 Message-ID: <1262190342-18611-1-git-send-email-avi@redhat.com> Cc: kvm@vger.kernel.org To: Marcelo Tosatti , Sheng Yang , Joerg Roedel Return-path: Received: from mx1.redhat.com ([209.132.183.28]:9751 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752273AbZL3QZr (ORCPT ); Wed, 30 Dec 2009 11:25:47 -0500 Sender: kvm-owner@vger.kernel.org List-ID: There are currently some inefficiencies in how we virtualize the fpu and cr0: - we trap changes to cr0.ts unconditionally; however, when the guest fpu is loaded, we're not really interested in cr0.ts (it's only needed when the host fpu is loaded, to prevent the guest from accessing it) - we deactivate the fpu on every guest context switch, for no reason at all Fix these issues by being as lazy as possible: deactivate the fpu at heavyweight context switch time, and when the fpu is active, give the guest ownership of cr0.ts. Joerg, I wasn't able to extend this to svm/npt. If we switch to the guest with the host fpu loaded, then we must set cr0.ts and enable cr0 intercepts. I think this is much more expensive than keeping the guest fpu active at all times. Avi Kivity (5): KVM: VMX: trace clts and lmsw instructions as cr accesses KVM: Replace read accesses of vcpu->arch.cr0 by an accessor KVM: VMX: Allow the guest to own some cr0 bits KVM: Lazify fpu activation and deactivation KVM: VMX: Give the guest ownership of cr0.ts when the fpu is active arch/x86/include/asm/kvm_host.h | 3 ++ arch/x86/kvm/emulate.c | 6 ++-- arch/x86/kvm/kvm_cache_regs.h | 12 +++++++++ arch/x86/kvm/mmu.c | 2 +- arch/x86/kvm/mmu.h | 2 +- arch/x86/kvm/svm.c | 46 ++++++++++++++++++++++-------------- arch/x86/kvm/vmx.c | 48 ++++++++++++++++++++++++-------------- arch/x86/kvm/x86.c | 26 ++++++++++++--------- 8 files changed, 93 insertions(+), 52 deletions(-)