From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753573AbeCVKTo (ORCPT ); Thu, 22 Mar 2018 06:19:44 -0400 Received: from ppsw-42.csi.cam.ac.uk ([131.111.8.142]:60690 "EHLO ppsw-42.csi.cam.ac.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751835AbeCVKTl (ORCPT ); Thu, 22 Mar 2018 06:19:41 -0400 X-Cam-AntiVirus: no malware found X-Cam-ScannerInfo: http://help.uis.cam.ac.uk/email-scanner-virus Subject: Re: [PATCH] KVM: X86: Fix the decoding of segment overrides in 64bit mode To: Paolo Bonzini , Wanpeng Li , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= References: <1521707651-9375-1-git-send-email-wanpengli@tencent.com> From: Andrew Cooper Message-ID: <49454fe4-16e2-4d8b-7ad5-9e488afc786e@citrix.com> Date: Thu, 22 Mar 2018 10:19:41 +0000 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-GB Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/03/2018 10:07, Paolo Bonzini wrote: > On 22/03/2018 09:34, Wanpeng Li wrote: >> From: Wanpeng Li >> >> Explicit segment overides other than %fs and %gs are documented as ignored by >> both Intel and AMD. >> >> In practice, this means that: >> >> * Explicit uses of %ss don't actually yield #SS[0] for non-canonical >> memory references. >> * Explicit uses of %{e,c,d}s don't override %rbp/%rsp-based memory references >> to yield #GP[0] for non-canonical memory references. >> >> Cc: Paolo Bonzini >> Cc: Radim Krčmář >> Signed-off-by: Wanpeng Li When porting fixes from other projects, it is customary to identify so in the commit message.  In this case, the fix you've ported is http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=b7dce29d9faf3597d009c853ed1fcbed9f7a7f68 Here is an example of how Xen ports fixes from Linux for the drivers that we share.  http://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=4e131596f1defec9407b6e60d584a696beaf5d7e >> --- >> arch/x86/kvm/emulate.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c >> index dd88158..5091255 100644 >> --- a/arch/x86/kvm/emulate.c >> +++ b/arch/x86/kvm/emulate.c >> @@ -5148,8 +5148,10 @@ int x86_decode_insn(struct x86_emulate_ctxt *ctxt, void *insn, int insn_len) >> case 0x2e: /* CS override */ >> case 0x36: /* SS override */ >> case 0x3e: /* DS override */ >> - has_seg_override = true; >> - ctxt->seg_override = (ctxt->b >> 3) & 3; >> + if (mode != X86EMUL_MODE_PROT64) { >> + has_seg_override = true; >> + ctxt->seg_override = (ctxt->b >> 3) & 3; >> + } >> break; >> case 0x64: /* FS override */ >> case 0x65: /* GS override */ >> > Testcase, please... If you want to crib from one, this is the testcase I made for Xen. http://xenbits.xen.org/docs/xtf/test-memop-seg.html With the impending KVM/PVH work which is ongoing, it will soon be easy to run Xen's HVM test suite unmodified under KVM, but we're not quite there yet. ~Andrew