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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 85D21C433EF for ; Tue, 12 Apr 2022 11:23:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351220AbiDLLZv (ORCPT ); Tue, 12 Apr 2022 07:25:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51700 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1351255AbiDLLZk (ORCPT ); Tue, 12 Apr 2022 07:25:40 -0400 Received: from mail.skyhub.de (mail.skyhub.de [IPv6:2a01:4f8:190:11c2::b:1457]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E6DA2B25A; Tue, 12 Apr 2022 03:07:51 -0700 (PDT) Received: from zn.tnic (p200300ea97156149329c23fffea6a903.dip0.t-ipconnect.de [IPv6:2003:ea:9715:6149:329c:23ff:fea6:a903]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.skyhub.de (SuperMail on ZX Spectrum 128k) with ESMTPSA id 9608C1EC04EC; Tue, 12 Apr 2022 12:07:45 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alien8.de; s=dkim; t=1649758065; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:in-reply-to:in-reply-to: references:references; bh=o3lXO1BKF/S5AzldA58rjm6HBnn56CuwTB6uiL2Y1Ag=; b=MnAIT7Er8JwAM4b0GD9rgLkDQyjcarmya9EyILrxMvNLKZ0HrhcSex/LUG4qj5DimKo4xp FUSPF+Ow9Iqn/lR66hENQLYudzalsAfqsYDdVNCEP3UQRqaJ97IASCFGZJ0A5WCoQftN+r A6Lci8BJ2YNNbYwSUe5vjOAJqh086DM= Date: Tue, 12 Apr 2022 12:07:46 +0200 From: Borislav Petkov To: Jane Chu Cc: david@fromorbit.com, djwong@kernel.org, dan.j.williams@intel.com, hch@infradead.org, vishal.l.verma@intel.com, dave.jiang@intel.com, agk@redhat.com, snitzer@redhat.com, dm-devel@redhat.com, ira.weiny@intel.com, willy@infradead.org, vgoyal@redhat.com, linux-fsdevel@vger.kernel.org, nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH v7 3/6] mce: fix set_mce_nospec to always unmap the whole page Message-ID: References: <20220405194747.2386619-1-jane.chu@oracle.com> <20220405194747.2386619-4-jane.chu@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220405194747.2386619-4-jane.chu@oracle.com> Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org On Tue, Apr 05, 2022 at 01:47:44PM -0600, Jane Chu wrote: > The set_memory_uc() approach doesn't work well in all cases. > For example, when "The VMM unmapped the bad page from guest > physical space and passed the machine check to the guest." > "The guest gets virtual #MC on an access to that page. > When the guest tries to do set_memory_uc() and instructs > cpa_flush() to do clean caches that results in taking another > fault / exception perhaps because the VMM unmapped the page > from the guest." I presume this is quoting someone... > Since the driver has special knowledge to handle NP or UC, > let's mark the poisoned page with NP and let driver handle it s/let's mark/mark/ > when it comes down to repair. > > Please refer to discussions here for more details. > https://lore.kernel.org/all/CAPcyv4hrXPb1tASBZUg-GgdVs0OOFKXMXLiHmktg_kFi7YBMyQ@mail.gmail.com/ > > Now since poisoned page is marked as not-present, in order to > avoid writing to a 'np' page and trigger kernel Oops, also fix You can write it out: "non-present page..." > pmem_do_write(). > > Fixes: 284ce4011ba6 ("x86/memory_failure: Introduce {set, clear}_mce_nospec()") > Signed-off-by: Jane Chu > --- > arch/x86/kernel/cpu/mce/core.c | 6 +++--- > arch/x86/mm/pat/set_memory.c | 18 ++++++------------ > drivers/nvdimm/pmem.c | 31 +++++++------------------------ > include/linux/set_memory.h | 4 ++-- > 4 files changed, 18 insertions(+), 41 deletions(-) For such mixed subsystem patches we probably should talk about who picks them up, eventually... > diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c > index 981496e6bc0e..fa67bb9d1afe 100644 > --- a/arch/x86/kernel/cpu/mce/core.c > +++ b/arch/x86/kernel/cpu/mce/core.c > @@ -579,7 +579,7 @@ static int uc_decode_notifier(struct notifier_block *nb, unsigned long val, > > pfn = mce->addr >> PAGE_SHIFT; > if (!memory_failure(pfn, 0)) { > - set_mce_nospec(pfn, whole_page(mce)); > + set_mce_nospec(pfn); > mce->kflags |= MCE_HANDLED_UC; > } > > @@ -1316,7 +1316,7 @@ static void kill_me_maybe(struct callback_head *cb) > > ret = memory_failure(p->mce_addr >> PAGE_SHIFT, flags); > if (!ret) { > - set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page); > + set_mce_nospec(p->mce_addr >> PAGE_SHIFT); > sync_core(); > return; > } > @@ -1342,7 +1342,7 @@ static void kill_me_never(struct callback_head *cb) > p->mce_count = 0; > pr_err("Kernel accessed poison in user space at %llx\n", p->mce_addr); > if (!memory_failure(p->mce_addr >> PAGE_SHIFT, 0)) > - set_mce_nospec(p->mce_addr >> PAGE_SHIFT, p->mce_whole_page); > + set_mce_nospec(p->mce_addr >> PAGE_SHIFT); > } Both that ->mce_whole_page and whole_page() look unused after this. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette