Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756399AbaDPTVP (ORCPT ); Wed, 16 Apr 2014 15:21:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54700 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755935AbaDPTVN (ORCPT ); Wed, 16 Apr 2014 15:21:13 -0400 Date: Wed, 16 Apr 2014 16:20:41 -0300 From: Marcelo Tosatti To: Nadav Amit Cc: gleb@kernel.org, pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] KVM: x86: Fix CR3 and LDT sel should not be saved in TSS Message-ID: <20140416192041.GC8773@amt.cnet> References: <1396885067-6491-1-git-send-email-namit@cs.technion.ac.il> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1396885067-6491-1-git-send-email-namit@cs.technion.ac.il> 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 On Mon, Apr 07, 2014 at 06:37:47PM +0300, Nadav Amit wrote: > According to Intel specifications, only general purpose registers and segment > selectors should are saved in the old TSS during 32-bit task-switch. should be > Signed-off-by: Nadav Amit > --- > arch/x86/kvm/emulate.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c > index 205b17e..0dec502 100644 > --- a/arch/x86/kvm/emulate.c > +++ b/arch/x86/kvm/emulate.c > @@ -2496,7 +2496,7 @@ static int task_switch_16(struct x86_emulate_ctxt *ctxt, > static void save_state_to_tss32(struct x86_emulate_ctxt *ctxt, > struct tss_segment_32 *tss) > { > - tss->cr3 = ctxt->ops->get_cr(ctxt, 3); > + /* CR3 and ldt selector are not saved intentionally */ > tss->eip = ctxt->_eip; > tss->eflags = ctxt->eflags; > tss->eax = reg_read(ctxt, VCPU_REGS_RAX); > @@ -2514,7 +2514,6 @@ static void save_state_to_tss32(struct x86_emulate_ctxt *ctxt, > tss->ds = get_segment_selector(ctxt, VCPU_SREG_DS); > tss->fs = get_segment_selector(ctxt, VCPU_SREG_FS); > tss->gs = get_segment_selector(ctxt, VCPU_SREG_GS); > - tss->ldt_selector = get_segment_selector(ctxt, VCPU_SREG_LDTR); > } > > static int load_state_from_tss32(struct x86_emulate_ctxt *ctxt, Only this hunk is enough ? > @@ -2604,6 +2603,8 @@ static int task_switch_32(struct x86_emulate_ctxt *ctxt, > struct tss_segment_32 tss_seg; > int ret; > u32 new_tss_base = get_desc_base(new_desc); > + u32 eip_offset = offsetof(struct tss_segment_32, eip); > + u32 ldt_sel_offset = offsetof(struct tss_segment_32, ldt_selector); > > ret = ops->read_std(ctxt, old_tss_base, &tss_seg, sizeof tss_seg, > &ctxt->exception); > @@ -2613,8 +2614,9 @@ static int task_switch_32(struct x86_emulate_ctxt *ctxt, > > save_state_to_tss32(ctxt, &tss_seg); > > - ret = ops->write_std(ctxt, old_tss_base, &tss_seg, sizeof tss_seg, > - &ctxt->exception); > + /* Only GP registers and segment selectors are saved */ > + ret = ops->write_std(ctxt, old_tss_base + eip_offset, &tss_seg.eip, > + ldt_sel_offset - eip_offset, &ctxt->exception); > if (ret != X86EMUL_CONTINUE) > /* FIXME: need to provide precise fault address */ > return ret; > -- > 1.7.10.4 > > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/