From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753324AbdE0PJ6 (ORCPT ); Sat, 27 May 2017 11:09:58 -0400 Received: from mail-ua0-f196.google.com ([209.85.217.196]:33683 "EHLO mail-ua0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750737AbdE0PJz (ORCPT ); Sat, 27 May 2017 11:09:55 -0400 MIME-Version: 1.0 In-Reply-To: <20170525203334.867-6-kirill.shutemov@linux.intel.com> References: <20170525203334.867-1-kirill.shutemov@linux.intel.com> <20170525203334.867-6-kirill.shutemov@linux.intel.com> From: Brian Gerst Date: Sat, 27 May 2017 11:09:54 -0400 Message-ID: Subject: Re: [PATCHv1, RFC 5/8] x86/mm: Fold p4d page table layer at runtime To: "Kirill A. Shutemov" Cc: Linus Torvalds , Andrew Morton , "the arch/x86 maintainers" , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Andi Kleen , Dave Hansen , Andy Lutomirski , linux-arch , Linux-MM , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 25, 2017 at 4:33 PM, Kirill A. Shutemov wrote: > This patch changes page table helpers to fold p4d at runtime. > The logic is the same as in . > > Signed-off-by: Kirill A. Shutemov > --- > arch/x86/include/asm/paravirt.h | 3 ++- > arch/x86/include/asm/pgalloc.h | 5 ++++- > arch/x86/include/asm/pgtable.h | 10 +++++++++- > 3 files changed, 15 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h > index 55fa56fe4e45..e934ed6dc036 100644 > --- a/arch/x86/include/asm/paravirt.h > +++ b/arch/x86/include/asm/paravirt.h > @@ -615,7 +615,8 @@ static inline void set_pgd(pgd_t *pgdp, pgd_t pgd) > > static inline void pgd_clear(pgd_t *pgdp) > { > - set_pgd(pgdp, __pgd(0)); > + if (!p4d_folded) > + set_pgd(pgdp, __pgd(0)); > } > > #endif /* CONFIG_PGTABLE_LEVELS == 5 */ > diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h > index b2d0cd8288aa..5c42262169d0 100644 > --- a/arch/x86/include/asm/pgalloc.h > +++ b/arch/x86/include/asm/pgalloc.h > @@ -155,6 +155,8 @@ static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud, > #if CONFIG_PGTABLE_LEVELS > 4 > static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, p4d_t *p4d) > { > + if (p4d_folded) > + return; > paravirt_alloc_p4d(mm, __pa(p4d) >> PAGE_SHIFT); > set_pgd(pgd, __pgd(_PAGE_TABLE | __pa(p4d))); > } > @@ -179,7 +181,8 @@ extern void ___p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d); > static inline void __p4d_free_tlb(struct mmu_gather *tlb, p4d_t *p4d, > unsigned long address) > { > - ___p4d_free_tlb(tlb, p4d); > + if (!p4d_folded) > + ___p4d_free_tlb(tlb, p4d); > } > > #endif /* CONFIG_PGTABLE_LEVELS > 4 */ > diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h > index 77037b6f1caa..4516a1bdcc31 100644 > --- a/arch/x86/include/asm/pgtable.h > +++ b/arch/x86/include/asm/pgtable.h > @@ -53,7 +53,7 @@ extern struct mm_struct *pgd_page_get_mm(struct page *page); > > #ifndef __PAGETABLE_P4D_FOLDED > #define set_pgd(pgdp, pgd) native_set_pgd(pgdp, pgd) > -#define pgd_clear(pgd) native_pgd_clear(pgd) > +#define pgd_clear(pgd) (!p4d_folded ? native_pgd_clear(pgd) : 0) > #endif > > #ifndef set_p4d > @@ -847,6 +847,8 @@ static inline unsigned long p4d_index(unsigned long address) > #if CONFIG_PGTABLE_LEVELS > 4 > static inline int pgd_present(pgd_t pgd) > { > + if (p4d_folded) > + return 1; > return pgd_flags(pgd) & _PAGE_PRESENT; > } > > @@ -864,16 +866,22 @@ static inline unsigned long pgd_page_vaddr(pgd_t pgd) > /* to find an entry in a page-table-directory. */ > static inline p4d_t *p4d_offset(pgd_t *pgd, unsigned long address) > { > + if (p4d_folded) > + return (p4d_t *)pgd; > return (p4d_t *)pgd_page_vaddr(*pgd) + p4d_index(address); > } > > static inline int pgd_bad(pgd_t pgd) > { > + if (p4d_folded) > + return 0; > return (pgd_flags(pgd) & ~_PAGE_USER) != _KERNPG_TABLE; > } > > static inline int pgd_none(pgd_t pgd) > { > + if (p4d_folded) > + return 0; > /* > * There is no need to do a workaround for the KNL stray > * A/D bit erratum here. PGDs only point to page tables These should use static_cpu_has(X86_FEATURE_LA57), so that it gets patched by alternatives. -- Brian Gerst