From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paolo Bonzini Subject: Re: [PATCH 09/13] KVM: x86: save/load state on SMM switch Date: Tue, 05 May 2015 11:37:11 +0200 Message-ID: <55488F47.8070904@redhat.com> References: <1430393772-27208-1-git-send-email-pbonzini@redhat.com> <1430393772-27208-10-git-send-email-pbonzini@redhat.com> <20150504195902.GA15848@potion.brq.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, bsd@redhat.com, guangrong.xiao@linux.intel.com, Yang Zhang , wanpeng.li@linux.intel.com To: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= Return-path: In-Reply-To: <20150504195902.GA15848@potion.brq.redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: kvm.vger.kernel.org On 04/05/2015 21:59, Radim Kr=C4=8Dm=C3=A1=C5=99 wrote: > > The big ugly one. This patch adds support for switching in and out= of > > system management mode, respectively upon receiving KVM_REQ_SMI and= upon > > executing a RSM instruction. Both 32- and 64-bit formats are suppo= rted > > for the SMM state save area. > >=20 > > Signed-off-by: Paolo Bonzini > > --- > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > > +static void rsm_set_desc_flags(struct desc_struct *desc, u16 flags= ) > > +{ > > + desc->g =3D (flags >> 15) & 1; > > + desc->d =3D (flags >> 14) & 1; > > + desc->l =3D (flags >> 13) & 1; > > + desc->avl =3D (flags >> 12) & 1; > > + desc->p =3D (flags >> 7) & 1; > > + desc->dpl =3D (flags >> 5) & 3; > > + desc->s =3D (flags >> 4) & 1; > > + desc->type =3D flags & 15; > > I can't find a description of this ... can you point me to a place wh= ere > the gap between 'p' and 'avl' is documented? > (Not that it matters unless the guest reads it, but it's a bit weird.= ) It turns out that access rights are stored in the same format as the VM= X access rights. However, they are shifted by 8, which my code above doesn't do (bug). The documentation is, of course, QEMU and Bochs :) but you can also fin= d it in http://www.rcollins.org/ftp/source/include/struc.inc. It is not exactly for SMM, but it is more or less the same. Paolo