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=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 DA3D1C4338F for ; Fri, 13 Aug 2021 11:12:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B3D1D61038 for ; Fri, 13 Aug 2021 11:12:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240053AbhHMLM4 (ORCPT ); Fri, 13 Aug 2021 07:12:56 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:60507 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239842AbhHMLMz (ORCPT ); Fri, 13 Aug 2021 07:12:55 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1628853148; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=n6jYw1yE2ZotbitHQWIkZk1MjslczNMHhrJaIV09Hiw=; b=D9sVw094fA13wCySD50ZeQavJ8kxW6y6v7zKAWw531HPqvs0KYHAdpb3Z8NV2ChQMdChsl xKDfuVW85QfpX2sMs2YSqlACwQiVJQvEDSOySIc2lMwRNatWBuD07L7HOG1nEOuqoDHU4l wMZaguq4BluzFyU2JSSbQjpNa4YPy2E= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-230-Ok5s957lPsOXDHjhBhLChA-1; Fri, 13 Aug 2021 07:12:27 -0400 X-MC-Unique: Ok5s957lPsOXDHjhBhLChA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id ADDE71853026; Fri, 13 Aug 2021 11:12:26 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6E1EB60C04; Fri, 13 Aug 2021 11:12:26 +0000 (UTC) From: Paolo Bonzini To: kvm@vger.kernel.org Cc: babu.moger@amd.com Subject: [PATCH kvm-unit-tests 1/2] access: optimize check for multiple reserved bits Date: Fri, 13 Aug 2021 07:12:24 -0400 Message-Id: <20210813111225.3603660-2-pbonzini@redhat.com> In-Reply-To: <20210813111225.3603660-1-pbonzini@redhat.com> References: <20210813111225.3603660-1-pbonzini@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Instead of using multiple ANDs statements, build a mask and check it for more than one set bit. Signed-off-by: Paolo Bonzini --- x86/access.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/x86/access.c b/x86/access.c index c71f39d..6285c8c 100644 --- a/x86/access.c +++ b/x86/access.c @@ -288,6 +288,7 @@ static int ac_test_bump_one(ac_test_t *at) static _Bool ac_test_legal(ac_test_t *at) { int flags = at->flags; + unsigned reserved; if (F(AC_ACCESS_FETCH) && F(AC_ACCESS_WRITE)) return false; @@ -321,8 +322,12 @@ static _Bool ac_test_legal(ac_test_t *at) * error code; the odds of a KVM bug are super low, and the odds of actually * being able to detect a bug are even lower. */ - if ((F(AC_PDE_BIT51) + F(AC_PDE_BIT36) + F(AC_PDE_BIT13) + - F(AC_PTE_BIT51) + F(AC_PTE_BIT36)) > 1) + reserved = (AC_PDE_BIT51_MASK | AC_PDE_BIT36_MASK | AC_PDE_BIT13_MASK | + AC_PTE_BIT51_MASK | AC_PTE_BIT36_MASK); + + /* Only test one reserved bit at a time. */ + reserved &= flags; + if (reserved & (reserved - 1)) return false; return true; -- 2.27.0