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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_IN_DEF_DKIM_WL autolearn=unavailable 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 5C64CC433E0 for ; Tue, 26 Jan 2021 09:11:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0827223102 for ; Tue, 26 Jan 2021 09:11:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390912AbhAZJKO (ORCPT ); Tue, 26 Jan 2021 04:10:14 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44484 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726565AbhAYSrN (ORCPT ); Mon, 25 Jan 2021 13:47:13 -0500 Received: from mail-pf1-x42d.google.com (mail-pf1-x42d.google.com [IPv6:2607:f8b0:4864:20::42d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 00C7FC061756 for ; Mon, 25 Jan 2021 10:46:32 -0800 (PST) Received: by mail-pf1-x42d.google.com with SMTP id f63so8908686pfa.13 for ; Mon, 25 Jan 2021 10:46:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=UoVeAcPYBoVP5YmNMUfLeCvrQBLfaM+e0XI1SRxnQQY=; b=CTh/m1HpQKQEbZttGur8vI9oMw39ZBDHSyW9iR9WHtr4mRBDIXg2aDJQLRU5MH/WSW WpQRXLxSLG0/6JcjMWSz0QEztRIxCckygLDFJOZNeeCATowa3UE3kkG4mU1mD48uY0LQ LmL2cFJcTyPUTsehLxdOgT+4zUsilRFbtH0qSAPdjKdv7kZqRmd1Wy0CidSi/tHi3QMF vj5feD/IxBqkgLK48RPJZUCgGLN4hAvDKCRMK47t6JC3yrvU2YFNG2HDGexcXdjqR6RY zmT3/BiTduj+n9Kqs6PMzilpqAwu5DMMsyxSu0GuPjJOixMxfwFanW3l5fO29ma4f6lM Uhug== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=UoVeAcPYBoVP5YmNMUfLeCvrQBLfaM+e0XI1SRxnQQY=; b=FdwGKhEt0WVNK+K896xDQpnsEQbb3lV5BpOfSqqcyNbQo2DU1p115TXaA9nCdbzUZT P7fDqZRsuicf4vLYNHrOTTP24Rr8q7ZOJ3NTnAd/u1t/q86cCpDtRzvkasIl2AwJsqjq i70GPCcr47OaF3uvlO/UlM4ViuDswxmq18PFIzEKanutM9INqr8gut+puHxylSfQlpG4 8zd6c4rwS4toPHrmLxWc0mbAO5vF+ZCs5i5CeS3tMDCeyKXScfniYYtKNvF8FK/PLQl7 EYebDWQ42MUnxqvv7DUJ+TtxLB21i0VgdPDS/lTMdo4fPPvkjand7LilvJsC+X2PCs+S Y0QA== X-Gm-Message-State: AOAM532jSIQ8DxMoxdiyBx/F4RsnGPyRTDVnyk3yo0u+GJS5cPQoTE3W /juOVYNyQ1i2XbpnxvxRhRHyuA== X-Google-Smtp-Source: ABdhPJxT7fdqgIb+7XNBiAwHrBNT5gYxRrewX2D5LTPe2Cm3sOy174fiftOEXjiG13Ue1bG20wl3Ww== X-Received: by 2002:a63:770b:: with SMTP id s11mr1899929pgc.342.1611600392333; Mon, 25 Jan 2021 10:46:32 -0800 (PST) Received: from google.com ([2620:15c:f:10:1ea0:b8ff:fe73:50f5]) by smtp.gmail.com with ESMTPSA id z3sm16881717pfb.157.2021.01.25.10.46.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 25 Jan 2021 10:46:31 -0800 (PST) Date: Mon, 25 Jan 2021 10:46:25 -0800 From: Sean Christopherson To: Greg KH Cc: Tianjia Zhang , Jarkko Sakkinen , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Shuah Khan , x86@kernel.org, linux-sgx@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Jia Zhang Subject: Re: [PATCH v3 5/5] x86/sgx: Remove redundant if conditions in sgx_encl_create Message-ID: References: <20210124062907.88229-1-tianjia.zhang@linux.alibaba.com> <20210124062907.88229-6-tianjia.zhang@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 24, 2021, Greg KH wrote: > On Sun, Jan 24, 2021 at 02:29:07PM +0800, Tianjia Zhang wrote: > > In this scenario, there is no case where va_page is NULL, and > > the error has been checked. The if condition statement here is > > redundant, so remove the condition detection. > > > > Signed-off-by: Tianjia Zhang > > --- > > arch/x86/kernel/cpu/sgx/ioctl.c | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/arch/x86/kernel/cpu/sgx/ioctl.c b/arch/x86/kernel/cpu/sgx/ioctl.c > > index 1c6ecf9fbeff..b0b829f1b761 100644 > > --- a/arch/x86/kernel/cpu/sgx/ioctl.c > > +++ b/arch/x86/kernel/cpu/sgx/ioctl.c > > @@ -66,9 +66,11 @@ static int sgx_encl_create(struct sgx_encl *encl, struct sgx_secs *secs) > > va_page = sgx_encl_grow(encl); > > if (IS_ERR(va_page)) > > return PTR_ERR(va_page); > > - else if (va_page) > > - list_add(&va_page->list, &encl->va_pages); > > - /* else the tail page of the VA page list had free slots. */ > > + > > + if (WARN_ONCE(!va_page, "non-empty VA page list before ECREATE")) > > + return -EIO; > > So you just crashed machines that have panic-on-warn enabled. Don't do > that for no reason, just handle the error and move on. The WARN will only fire if someone introduces a kernel bug. It's one part documentation, two parts helping detect future breakage. Even if the VA page management is significantly reworked, I'm having a hard time envisioning a scenario where adding VA pages before ECREATE would be anything but a kernel bug.