From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gui Jianfeng Subject: Re: [PATCH] KMV: VMX: consult IA32_VMX_EPT_VPID_CAP to determine EPT paging-structure memory type Date: Fri, 26 Mar 2010 09:39:51 +0800 Message-ID: <4BAC1067.6050004@cn.fujitsu.com> References: <4BA73322.5020001@cn.fujitsu.com> <201003221713.26941.sheng@linux.intel.com> <4BA895A3.4060807@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Cc: Sheng Yang , mtosatti@redhat.com, kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from cn.fujitsu.com ([222.73.24.84]:56636 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751968Ab0CZBkN (ORCPT ); Thu, 25 Mar 2010 21:40:13 -0400 In-Reply-To: <4BA895A3.4060807@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Avi Kivity wrote: > On 03/22/2010 11:13 AM, Sheng Yang wrote: >> >>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c >>> index 06108f3..f971b9b 100644 >>> --- a/arch/x86/kvm/vmx.c >>> +++ b/arch/x86/kvm/vmx.c >>> @@ -1804,9 +1804,15 @@ static u64 construct_eptp(unsigned long root_hpa) >>> { >>> u64 eptp; >>> >>> - /* TODO write the value reading from MSR */ >>> - eptp = VMX_EPT_DEFAULT_MT | >>> - VMX_EPT_DEFAULT_GAW<< VMX_EPT_GAW_EPTP_SHIFT; >>> + if (cpu_has_vmx_eptp_writeback()) >>> + eptp = VMX_EPT_MT_WRBACK | >>> + VMX_EPT_DEFAULT_GAW<< VMX_EPT_GAW_EPTP_SHIFT; >>> >> I prefer to ensure WB is supported and used as default. Otherwise it >> would be >> a big trouble for memory subsystem(to use UC for all memory). Both WB >> and UC >> EPT memory types are ensured to be support in hardware. >> >> And you can remove VMX_EPT_DEFAULT_MT as well. >> > > I agree, hopefully we never ever see a cpu that doesn't support EPT WB. OK, seems we don't need to have this concern. :) >