From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [patch 3/3] KVM: VMX: handle segment limit granularity special case in software Date: Thu, 17 Jul 2008 13:03:57 +0300 Message-ID: <487F190D.3090701@qumranet.com> References: <20080716220709.886199616@localhost.localdomain> <20080716221401.578260549@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org To: Marcelo Tosatti Return-path: Received: from il.qumranet.com ([212.179.150.194]:27651 "EHLO il.qumranet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755158AbYGQKD7 (ORCPT ); Thu, 17 Jul 2008 06:03:59 -0400 In-Reply-To: <20080716221401.578260549@localhost.localdomain> Sender: kvm-owner@vger.kernel.org List-ID: Marcelo Tosatti wrote: > As the comment in the diff mentions, VMX does not accept any bit in > the range 11:0 of ES,CS,FS,GS,SS segment registers limit field to > be zero with the granulity bit set to one. > > So clear granularity and adjust the limit accordingly. > > Signed-off-by: Marcelo Tosatti > > Index: kvm/arch/x86/kvm/vmx.c > =================================================================== > --- kvm.orig/arch/x86/kvm/vmx.c > +++ kvm/arch/x86/kvm/vmx.c > @@ -1665,6 +1665,22 @@ static void vmx_set_segment(struct kvm_v > return; > } > vmcs_writel(sf->base, var->base); > + > + /* > + * section 22.3.1.2: > + * - If any bit in the limit field in the range 11:0 is 0, G must be 0. > + * - If any bit in the limit field in the range 31:20 is 1, G must be 1. > + */ > + if (!vcpu->arch.rmode.active && !var->unusable && > + seg != VCPU_SREG_TR && seg != VCPU_SREG_LDTR) { > +#define SEG_MASK ((1 << 12)-1) > + if (var->g && (var->limit & SEG_MASK) != SEG_MASK) { > + var->g = 0; > + var->limit <<= 12; > + var->limit |= SEG_MASK; > + } > + } > + Both kvm_segment::limit and vmx's GUEST_xS_LIMIT are normalized (always in bytes), so I don't see why you are modifying var->limit (which is an input parameter!) -- error compiling committee.c: too many arguments to function