From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1884DC10F0E for ; Mon, 15 Apr 2019 19:00:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E38852087C for ; Mon, 15 Apr 2019 19:00:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728246AbfDOTA3 (ORCPT ); Mon, 15 Apr 2019 15:00:29 -0400 Received: from mga01.intel.com ([192.55.52.88]:49603 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728126AbfDOTA2 (ORCPT ); Mon, 15 Apr 2019 15:00:28 -0400 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga101.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Apr 2019 12:00:27 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.60,354,1549958400"; d="scan'208,223";a="142960250" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.181]) by orsmga003.jf.intel.com with ESMTP; 15 Apr 2019 12:00:27 -0700 Date: Mon, 15 Apr 2019 12:00:27 -0700 From: Sean Christopherson To: nadav.amit@gmail.com Cc: Paolo Bonzini , kvm@vger.kernel.org Subject: Re: [kvm-unit-tests PATCH] x86: Prevent APIC base address from changing in test_enable_x2apic() Message-ID: <20190415190027.GJ24010@linux.intel.com> References: <20190415183100.6827-1-nadav.amit@gmail.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="Clx92ZfkiYIKRjnr" Content-Disposition: inline In-Reply-To: <20190415183100.6827-1-nadav.amit@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org --Clx92ZfkiYIKRjnr Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Mon, Apr 15, 2019 at 11:31:00AM -0700, nadav.amit@gmail.com wrote: > From: Nadav Amit > > test_enable_x2apic() unintentionally changes the APIC base address to > zero and resets the BSP indication. This actually causes the local APIC > to overlap the IDT area, which is wrong. Prevent it from happening by > keeping the APIC base address and BSP-bit as it was before. > > Signed-off-by: Nadav Amit > --- > x86/apic.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/x86/apic.c b/x86/apic.c > index 51744cf..0849f87 100644 > --- a/x86/apic.c > +++ b/x86/apic.c > @@ -90,11 +90,11 @@ static void test_enable_x2apic(void) > report("disabled to x2apic enabled", > test_write_apicbase_exception(APIC_EN | APIC_EXTD)); > > - wrmsr(MSR_IA32_APICBASE, APIC_EN); > + wrmsr(MSR_IA32_APICBASE, APIC_EN | APIC_DEFAULT_PHYS_BASE | APIC_BSP); > report("apic enabled to invalid state", > test_write_apicbase_exception(APIC_EXTD)); > > - wrmsr(MSR_IA32_APICBASE, APIC_EN | APIC_EXTD); > + wrmsr(MSR_IA32_APICBASE, APIC_EN | APIC_EXTD | APIC_DEFAULT_PHYS_BASE | APIC_BSP); It probably doesn't matter since AFAIK kvm-unit-tests always uses the default base, but preserving the current base+BSP would be preferred. The #GP tests get away with using APIC_DEFAULT_PHYS_BASE because the WRMSR will never succeed, but even that is poor form. And the test should also reset to xAPIC when it's done. I think the attached patch covers everything. > apic_write(APIC_SPIV, 0x1ff); > } else { > printf("x2apic not detected\n"); > -- > 2.17.1 > --Clx92ZfkiYIKRjnr Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="0001-x86-apic-Preserve-APIC-base-and-BSP-bits-during-x2AP.patch" >From 0905302c23f20f67483b281e33f1930135087e3a Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 15 Apr 2019 11:53:00 -0700 Subject: [PATCH] x86: apic: Preserve APIC base and BSP bits during x2APIC tests ...and reset to xAPIC mode unless x2APIC was already enabled. Signed-off-by: Sean Christopherson --- x86/apic.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/x86/apic.c b/x86/apic.c index 51744cf..02b6128 100644 --- a/x86/apic.c +++ b/x86/apic.c @@ -69,33 +69,39 @@ static void do_write_apicbase(void *data) static bool test_write_apicbase_exception(u64 data) { - data |= APIC_DEFAULT_PHYS_BASE | APIC_BSP; return test_for_exception(GP_VECTOR, do_write_apicbase, &data); } static void test_enable_x2apic(void) { + u64 orig_apicbase = rdmsr(MSR_IA32_APICBASE); + u64 apicbase; + if (enable_x2apic()) { printf("x2apic enabled\n"); + apicbase = orig_apicbase & ~(APIC_EN | APIC_EXTD); report("x2apic enabled to invalid state", - test_write_apicbase_exception(APIC_EXTD)); + test_write_apicbase_exception(apicbase | APIC_EXTD)); report("x2apic enabled to apic enabled", - test_write_apicbase_exception(APIC_EN)); + test_write_apicbase_exception(apicbase | APIC_EN)); report("x2apic enabled to disabled state", - !test_write_apicbase_exception(0)); + !test_write_apicbase_exception(apicbase | 0)); report("disabled to invalid state", - test_write_apicbase_exception(APIC_EXTD)); + test_write_apicbase_exception(apicbase | APIC_EXTD)); report("disabled to x2apic enabled", - test_write_apicbase_exception(APIC_EN | APIC_EXTD)); + test_write_apicbase_exception(apicbase | APIC_EN | APIC_EXTD)); - wrmsr(MSR_IA32_APICBASE, APIC_EN); + wrmsr(MSR_IA32_APICBASE, apicbase | APIC_EN); report("apic enabled to invalid state", - test_write_apicbase_exception(APIC_EXTD)); + test_write_apicbase_exception(apicbase | APIC_EXTD)); - wrmsr(MSR_IA32_APICBASE, APIC_EN | APIC_EXTD); + wrmsr(MSR_IA32_APICBASE, apicbase | APIC_EN | APIC_EXTD); apic_write(APIC_SPIV, 0x1ff); + + if (!(orig_apicbase & APIC_EXTD)) + reset_apic(); } else { printf("x2apic not detected\n"); -- 2.21.0 --Clx92ZfkiYIKRjnr--