From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f199.google.com (mail-qk0-f199.google.com [209.85.220.199]) by kanga.kvack.org (Postfix) with ESMTP id 470EA6B000A for ; Tue, 17 Apr 2018 17:56:38 -0400 (EDT) Received: by mail-qk0-f199.google.com with SMTP id a124so1574407qkb.19 for ; Tue, 17 Apr 2018 14:56:38 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id 16sor11001468qtp.35.2018.04.17.14.56.37 for (Google Transport Security); Tue, 17 Apr 2018 14:56:37 -0700 (PDT) MIME-Version: 1.0 Reply-To: mceier+kernel@gmail.com In-Reply-To: <20180417211304.7B3F1FDB@viggo.jf.intel.com> References: <20180417211302.421F6442@viggo.jf.intel.com> <20180417211304.7B3F1FDB@viggo.jf.intel.com> From: Mariusz Ceier Date: Tue, 17 Apr 2018 23:56:36 +0200 Message-ID: Subject: Re: [PATCH 2/2] x86, pti: fix boot warning from Global-bit setting Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Linux Kernel Mailing List , linux-mm@kvack.org, Aaro Koskinen , aarcange@redhat.com, luto@kernel.org, arjan@linux.intel.com, Borislav Petkov , dan.j.williams@intel.com, dwmw2@infradead.org, gregkh@linuxfoundation.org, hughd@google.com, jpoimboe@redhat.com, jgross@suse.com, keescook@google.com, Linus Torvalds , namit@vmware.com, peterz@infradead.org, Thomas Gleixner On 17 April 2018 at 23:13, Dave Hansen wrote: > > These are _very_ lightly tested. I'm throwing them out there for > folks are looking for a fix. > > --- > > From: Dave Hansen > > pageattr.c is not friendly when it encounters empty (zero) PTEs. The > kernel linear map is exempt from these checks, but kernel text is not. > This patch adds the code to also exempt kernel text from these checks. > The proximate cause of these warnings was most likely an __init area > that spanned a 2MB page boundary that resulted in a "zero" PMD. > > Signed-off-by: Dave Hansen > Fixes: 39114b7a7 (x86/pti: Never implicitly clear _PAGE_GLOBAL for kernel image) > Reported-by: Mariusz Ceier > Reported-by: Aaro Koskinen > Cc: Andrea Arcangeli > Cc: Andy Lutomirski > Cc: Arjan van de Ven > Cc: Borislav Petkov > Cc: Dan Williams > Cc: David Woodhouse > Cc: Greg Kroah-Hartman > Cc: Hugh Dickins > Cc: Josh Poimboeuf > Cc: Juergen Gross > Cc: Kees Cook > Cc: Linus Torvalds > Cc: Nadav Amit > Cc: Peter Zijlstra > Cc: Thomas Gleixner > Cc: linux-mm@kvack.org > --- > > b/arch/x86/mm/pageattr.c | 17 +++++++++++++++-- > 1 file changed, 15 insertions(+), 2 deletions(-) > > diff -puN arch/x86/mm/pageattr.c~pti-glb-warning-inpageattr arch/x86/mm/pageattr.c > --- a/arch/x86/mm/pageattr.c~pti-glb-warning-inpageattr 2018-04-17 14:10:22.695395554 -0700 > +++ b/arch/x86/mm/pageattr.c 2018-04-17 14:10:22.721395554 -0700 > @@ -1151,6 +1151,16 @@ static int populate_pgd(struct cpa_data > return 0; > } > > +bool __cpa_pfn_in_highmap(unsigned long pfn) > +{ > + /* > + * Kernel text has an alias mapping at a high address, known > + * here as "highmap". > + */ > + return within_inclusive(pfn, highmap_start_pfn(), > + highmap_end_pfn()); > +} > + > static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr, > int primary) > { > @@ -1183,6 +1193,10 @@ static int __cpa_process_fault(struct cp > cpa->numpages = 1; > cpa->pfn = __pa(vaddr) >> PAGE_SHIFT; > return 0; > + > + } else if (__cpa_pfn_in_highmap(cpa->pfn)) { > + /* Faults in the highmap are OK, so do not warn: */ > + return -EFAULT; > } else { > WARN(1, KERN_WARNING "CPA: called for zero pte. " > "vaddr = %lx cpa->vaddr = %lx\n", vaddr, > @@ -1335,8 +1349,7 @@ static int cpa_process_alias(struct cpa_ > * to touch the high mapped kernel as well: > */ > if (!within(vaddr, (unsigned long)_text, _brk_end) && > - within_inclusive(cpa->pfn, highmap_start_pfn(), > - highmap_end_pfn())) { > + __cpa_pfn_in_highmap(cpa->pfn)) { > unsigned long temp_cpa_vaddr = (cpa->pfn << PAGE_SHIFT) + > __START_KERNEL_map - phys_base; > alias_cpa = *cpa; > _ I confirm that these 2 patches fix the BUG for me in kernel 4.17.0-rc1. Thanks