From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933357AbaLEBAl (ORCPT ); Thu, 4 Dec 2014 20:00:41 -0500 Received: from mga11.intel.com ([192.55.52.93]:37577 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932717AbaLEBAk (ORCPT ); Thu, 4 Dec 2014 20:00:40 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.97,862,1389772800"; d="scan'208";a="425276953" Date: Fri, 5 Dec 2014 08:40:24 +0800 From: Wanpeng Li To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rkrcmar@redhat.com Subject: Re: [PATCH 5/9] KVM: cpuid: set CPUID(EAX=0xd,ECX=1).EBX correctly Message-ID: <20141205004024.GB6967@kernel> Reply-To: Wanpeng Li References: <1417708634-24333-1-git-send-email-pbonzini@redhat.com> <1417708634-24333-6-git-send-email-pbonzini@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1417708634-24333-6-git-send-email-pbonzini@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Paolo, On Thu, Dec 04, 2014 at 04:57:10PM +0100, Paolo Bonzini wrote: >This is the size of the XSAVES area. This starts providing guest support >for XSAVES (with no support yet for supervisor states, i.e. XSS == 0 >always in guests for now). > >Wanpeng Li suggested testing XSAVEC as well as XSAVES, since in practice >no real processor exists that only has one of them, and there is no >other way for userspace programs to compute the area of the XSAVEC >save area. CPUID(EAX=0xd,ECX=1).EBX provides an upper bound. > >Suggested-by: Radim Krčmář >Reviewed-by: Radim Krčmář >Signed-off-by: Wanpeng Li >Signed-off-by: Paolo Bonzini >--- > arch/x86/kvm/cpuid.c | 22 ++++++++++++++++------ > 1 file changed, 16 insertions(+), 6 deletions(-) > >diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c >index e24df01ab118..2f7bc2de9915 100644 >--- a/arch/x86/kvm/cpuid.c >+++ b/arch/x86/kvm/cpuid.c >@@ -23,7 +23,7 @@ > #include "mmu.h" > #include "trace.h" > >-static u32 xstate_required_size(u64 xstate_bv) >+static u32 xstate_required_size(u64 xstate_bv, bool compacted) > { > int feature_bit = 0; > u32 ret = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET; >@@ -31,9 +31,10 @@ static u32 xstate_required_size(u64 xstate_bv) > xstate_bv &= XSTATE_EXTEND_MASK; > while (xstate_bv) { > if (xstate_bv & 0x1) { >- u32 eax, ebx, ecx, edx; >+ u32 eax, ebx, ecx, edx, offset; > cpuid_count(0xD, feature_bit, &eax, &ebx, &ecx, &edx); >- ret = max(ret, eax + ebx); >+ offset = compacted ? ret : ebx; >+ ret = max(ret, offset + eax); > } > > xstate_bv >>= 1; >@@ -87,9 +88,13 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu) > (best->eax | ((u64)best->edx << 32)) & > kvm_supported_xcr0(); > vcpu->arch.guest_xstate_size = best->ebx = >- xstate_required_size(vcpu->arch.xcr0); >+ xstate_required_size(vcpu->arch.xcr0, false); > } > >+ best = kvm_find_cpuid_entry(vcpu, 0xD, 1); >+ if (best && (best->eax & (F(XSAVES)|F(XSAVEC)))) >+ best->ebx = xstate_required_size(vcpu->arch.xcr0, true); >+ > /* > * The existing code assumes virtual address is 48-bit in the canonical > * address checks; exit if it is ever changed. >@@ -470,9 +475,14 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function, > goto out; > > do_cpuid_1_ent(&entry[i], function, idx); >- if (idx == 1) When if (idx == 1) is added in this patchset? I suspect that you miss to add your patch "kvm: x86: mask out XSAVES" in this patchset. Regards, Wanpeng Li >+ if (idx == 1) { > entry[i].eax &= kvm_supported_word10_x86_features; >- else if (entry[i].eax == 0 || !(supported & mask)) >+ entry[i].ebx = 0; >+ if (entry[i].eax & (F(XSAVES)|F(XSAVEC))) >+ entry[i].ebx = >+ xstate_required_size(supported, >+ true); >+ } else if (entry[i].eax == 0 || !(supported & mask)) > continue; > entry[i].flags |= > KVM_CPUID_FLAG_SIGNIFCANT_INDEX; >-- >1.8.3.1 >