From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v3] kvm/fpu: Enable fully eager restore kvm FPU Date: Thu, 13 Sep 2012 19:38:40 +0300 Message-ID: <50520C10.9010805@redhat.com> References: <1347437424-3006-1-git-send-email-xudong.hao@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, xiantao.zhang@intel.com To: Xudong Hao Return-path: Received: from mx1.redhat.com ([209.132.183.28]:28823 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758253Ab2IMQin (ORCPT ); Thu, 13 Sep 2012 12:38:43 -0400 In-Reply-To: <1347437424-3006-1-git-send-email-xudong.hao@intel.com> Sender: kvm-owner@vger.kernel.org List-ID: On 09/12/2012 11:10 AM, Xudong Hao wrote: > Enable KVM FPU fully eager restore, if there is other FPU state which isn't > tracked by CR0.TS bit. > > v3 changes from v2: > - Make fpu active explicitly while guest xsave is enabling and non-lazy xstate bit > exist. > > v2 changes from v1: > - Expand KVM_XSTATE_LAZY to 64 bits before negating it. > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 248c2b4..853e875 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -3028,6 +3028,8 @@ static void vmx_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0) > > if (!vcpu->fpu_active) > hw_cr0 |= X86_CR0_TS | X86_CR0_MP; > + else > + hw_cr0 &= ~(X86_CR0_TS | X86_CR0_MP); > Why? The guest may wish to receive #NM faults. > vmcs_writel(CR0_READ_SHADOW, cr0); > vmcs_writel(GUEST_CR0, hw_cr0); > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 20f2266..183cf60 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -560,6 +560,8 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr) > return 1; > if (xcr0 & ~host_xcr0) > return 1; > + if (xcr0 & ~((u64)KVM_XSTATE_LAZY)) > + vcpu->fpu_active = 1; > vcpu->arch.xcr0 = xcr0; > vcpu->guest_xcr0_loaded = 0; > return 0; > @@ -5969,7 +5971,18 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu) > vcpu->guest_fpu_loaded = 0; > fpu_save_init(&vcpu->arch.guest_fpu); > ++vcpu->stat.fpu_reload; > - kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu); > + /* > + * Currently KVM trigger FPU restore by #NM (via CR0.TS), > + * till now only XCR0.bit0, XCR0.bit1, XCR0.bit2 is tracked "currently", "till now", don't tell someone reading the code in six months anything. Just say how the code works. > + * by TS bit, there might be other FPU state is not tracked > + * by TS bit. Here it only make FPU deactivate request and do > + * FPU lazy restore for these cases: 1)xsave isn't enabled > + * in guest, 2)all guest FPU states can be tracked by TS bit. > + * For others, doing fully FPU eager restore. > + */ > + if (!kvm_read_cr4_bits(vcpu, X86_CR4_OSXSAVE) || > + !(vcpu->arch.xcr0 & ~((u64)KVM_XSTATE_LAZY))) > + kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu); > trace_kvm_fpu(0); > } > > -- error compiling committee.c: too many arguments to function