From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f172.google.com (mail-wi0-f172.google.com [209.85.212.172]) by kanga.kvack.org (Postfix) with ESMTP id 970676B0038 for ; Thu, 9 Jul 2015 23:57:12 -0400 (EDT) Received: by widjy10 with SMTP id jy10so4691691wid.1 for ; Thu, 09 Jul 2015 20:57:12 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id cd7si1319192wib.4.2015.07.09.20.57.10 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 09 Jul 2015 20:57:10 -0700 (PDT) Message-ID: <559F4293.1090801@suse.com> Date: Fri, 10 Jul 2015 05:57:07 +0200 From: Juergen Gross MIME-Version: 1.0 Subject: Re: [PATCH 1/2] x86: Fix pXd_flags() to handle _PAGE_PAT_LARGE References: <1436461431-27305-1-git-send-email-toshi.kani@hp.com> <1436461431-27305-2-git-send-email-toshi.kani@hp.com> In-Reply-To: <1436461431-27305-2-git-send-email-toshi.kani@hp.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Toshi Kani , hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com Cc: akpm@linux-foundation.org, bp@alien8.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, konrad.wilk@oracle.com, elliott@hp.com On 07/09/2015 07:03 PM, Toshi Kani wrote: > The PAT bit gets relocated to bit 12 when PUD and PMD mappings are > used. This bit 12, however, is not covered by PTE_FLAGS_MASK, which > is corrently used for masking the flag bits for all cases. > > Fix pud_flags() and pmd_flags() to cover the PAT bit, _PAGE_PAT_LARGE, > when they are used to map a large page with _PAGE_PSE set. > > Signed-off-by: Toshi Kani > Cc: Juergen Gross > Cc: Konrad Wilk > Cc: Robert Elliott > Cc: Thomas Gleixner > Cc: H. Peter Anvin > Cc: Ingo Molnar > Cc: Borislav Petkov > Cc: Andrew Morton > --- > arch/x86/include/asm/pgtable_types.h | 16 +++++++++++++--- > 1 file changed, 13 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h > index 13f310b..caaf45c 100644 > --- a/arch/x86/include/asm/pgtable_types.h > +++ b/arch/x86/include/asm/pgtable_types.h > @@ -212,9 +212,13 @@ enum page_cache_mode { > /* PTE_PFN_MASK extracts the PFN from a (pte|pmd|pud|pgd)val_t */ > #define PTE_PFN_MASK ((pteval_t)PHYSICAL_PAGE_MASK) > > -/* PTE_FLAGS_MASK extracts the flags from a (pte|pmd|pud|pgd)val_t */ > +/* Extracts the flags from a (pte|pmd|pud|pgd)val_t of a 4KB page */ > #define PTE_FLAGS_MASK (~PTE_PFN_MASK) > > +/* Extracts the flags from a (pmd|pud)val_t of a (1GB|2MB) page */ > +#define PMD_FLAGS_MASK_LARGE ((~PTE_PFN_MASK) | _PAGE_PAT_LARGE) > +#define PUD_FLAGS_MASK_LARGE ((~PTE_PFN_MASK) | _PAGE_PAT_LARGE) > + > typedef struct pgprot { pgprotval_t pgprot; } pgprot_t; > > typedef struct { pgdval_t pgd; } pgd_t; > @@ -278,12 +282,18 @@ static inline pmdval_t native_pmd_val(pmd_t pmd) > > static inline pudval_t pud_flags(pud_t pud) > { > - return native_pud_val(pud) & PTE_FLAGS_MASK; > + if (native_pud_val(pud) & _PAGE_PSE) > + return native_pud_val(pud) & PUD_FLAGS_MASK_LARGE; > + else > + return native_pud_val(pud) & PTE_FLAGS_MASK; > } > > static inline pmdval_t pmd_flags(pmd_t pmd) > { > - return native_pmd_val(pmd) & PTE_FLAGS_MASK; > + if (native_pmd_val(pmd) & _PAGE_PSE) > + return native_pmd_val(pmd) & PMD_FLAGS_MASK_LARGE; > + else > + return native_pmd_val(pmd) & PTE_FLAGS_MASK; > } Hmm, I think this covers only half of the problem. pud_pfn() and pmd_pfn() will return wrong results for large pages with PAT bit set as well. I'd rather use something like: static inline unsigned long pmd_pfn_mask(pmd_t pmd) { if (pmd_large(pmd)) return PMD_PAGE_MASK & PHYSICAL_PAGE_MASK; else return PTE_PFN_MASK; } static inline unsigned long pmd_flags_mask(pmd_t pmd) { if (pmd_large(pmd)) return ~(PMD_PAGE_MASK & PHYSICAL_PAGE_MASK); else return ~PTE_PFN_MASK; } static inline unsigned long pmd_pfn(pmd_t pmd) { return (pmd_val(pmd) & pmd_pfn_mask(pmd)) >> PAGE_SHIFT; } static inline pmdval_t pmd_flags(pmd_t pmd) { return native_pmd_val(pmd) & ~pmd_flags_mask(pmd); } Juergen -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org