From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3v2N6N5cmWzDqR8 for ; Tue, 17 Jan 2017 06:07:56 +1100 (AEDT) Received: from pps.filterd (m0098417.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v0GJ3rCU143657 for ; Mon, 16 Jan 2017 14:07:53 -0500 Received: from e35.co.us.ibm.com (e35.co.us.ibm.com [32.97.110.153]) by mx0a-001b2d01.pphosted.com with ESMTP id 280xd87246-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Mon, 16 Jan 2017 14:07:53 -0500 Received: from localhost by e35.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 16 Jan 2017 12:07:52 -0700 From: Reza Arbab To: Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras Cc: linuxppc-dev@lists.ozlabs.org, "Aneesh Kumar K.V" , Balbir Singh , Alistair Popple Subject: [PATCH v5 3/4] powerpc/mm: add radix__remove_section_mapping() Date: Mon, 16 Jan 2017 13:07:45 -0600 In-Reply-To: <1484593666-8001-1-git-send-email-arbab@linux.vnet.ibm.com> References: <1484593666-8001-1-git-send-email-arbab@linux.vnet.ibm.com> Message-Id: <1484593666-8001-4-git-send-email-arbab@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Tear down and free the four-level page tables of physical mappings during memory hotremove. Borrow the basic structure of remove_pagetable() and friends from the identically-named x86 functions. Reduce the frequency of tlb flushes and page_table_lock spinlocks by only doing them in the outermost function. There was some question as to whether the locking is needed at all. Leave it for now, but we could consider dropping it. Memory must be offline to be removed, thus not in use. So there shouldn't be the sort of concurrent page walking activity here that might prompt us to use RCU. Signed-off-by: Reza Arbab --- arch/powerpc/include/asm/book3s/64/radix.h | 1 + arch/powerpc/mm/pgtable-book3s64.c | 2 +- arch/powerpc/mm/pgtable-radix.c | 133 +++++++++++++++++++++++++++++ 3 files changed, 135 insertions(+), 1 deletion(-) diff --git a/arch/powerpc/include/asm/book3s/64/radix.h b/arch/powerpc/include/asm/book3s/64/radix.h index 43c2571..0032b66 100644 --- a/arch/powerpc/include/asm/book3s/64/radix.h +++ b/arch/powerpc/include/asm/book3s/64/radix.h @@ -294,6 +294,7 @@ static inline unsigned long radix__get_tree_size(void) #ifdef CONFIG_MEMORY_HOTPLUG int radix__create_section_mapping(unsigned long start, unsigned long end); +int radix__remove_section_mapping(unsigned long start, unsigned long end); #endif /* CONFIG_MEMORY_HOTPLUG */ #endif /* __ASSEMBLY__ */ #endif diff --git a/arch/powerpc/mm/pgtable-book3s64.c b/arch/powerpc/mm/pgtable-book3s64.c index 2b13f6b..b798ff6 100644 --- a/arch/powerpc/mm/pgtable-book3s64.c +++ b/arch/powerpc/mm/pgtable-book3s64.c @@ -139,7 +139,7 @@ int create_section_mapping(unsigned long start, unsigned long end) int remove_section_mapping(unsigned long start, unsigned long end) { if (radix_enabled()) - return -ENODEV; + return radix__remove_section_mapping(start, end); return hash__remove_section_mapping(start, end); } diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c index 075b4ec..cfba666 100644 --- a/arch/powerpc/mm/pgtable-radix.c +++ b/arch/powerpc/mm/pgtable-radix.c @@ -476,10 +476,143 @@ void radix__setup_initial_memory_limit(phys_addr_t first_memblock_base, } #ifdef CONFIG_MEMORY_HOTPLUG +static void free_pte_table(pte_t *pte_start, pmd_t *pmd) +{ + pte_t *pte; + int i; + + for (i = 0; i < PTRS_PER_PTE; i++) { + pte = pte_start + i; + if (!pte_none(*pte)) + return; + } + + pte_free_kernel(&init_mm, pte_start); + pmd_clear(pmd); +} + +static void free_pmd_table(pmd_t *pmd_start, pud_t *pud) +{ + pmd_t *pmd; + int i; + + for (i = 0; i < PTRS_PER_PMD; i++) { + pmd = pmd_start + i; + if (!pmd_none(*pmd)) + return; + } + + pmd_free(&init_mm, pmd_start); + pud_clear(pud); +} + +static void remove_pte_table(pte_t *pte_start, unsigned long addr, + unsigned long end) +{ + unsigned long next; + pte_t *pte; + + pte = pte_start + pte_index(addr); + for (; addr < end; addr = next, pte++) { + next = (addr + PAGE_SIZE) & PAGE_MASK; + if (next > end) + next = end; + + if (!pte_present(*pte)) + continue; + + pte_clear(&init_mm, addr, pte); + } +} + +static void remove_pmd_table(pmd_t *pmd_start, unsigned long addr, + unsigned long end) +{ + unsigned long next; + pte_t *pte_base; + pmd_t *pmd; + + pmd = pmd_start + pmd_index(addr); + for (; addr < end; addr = next, pmd++) { + next = pmd_addr_end(addr, end); + + if (!pmd_present(*pmd)) + continue; + + if (pmd_huge(*pmd)) { + pte_clear(&init_mm, addr, (pte_t *)pmd); + continue; + } + + pte_base = (pte_t *)pmd_page_vaddr(*pmd); + remove_pte_table(pte_base, addr, next); + free_pte_table(pte_base, pmd); + } +} + +static void remove_pud_table(pud_t *pud_start, unsigned long addr, + unsigned long end) +{ + unsigned long next; + pmd_t *pmd_base; + pud_t *pud; + + pud = pud_start + pud_index(addr); + for (; addr < end; addr = next, pud++) { + next = pud_addr_end(addr, end); + + if (!pud_present(*pud)) + continue; + + if (pud_huge(*pud)) { + pte_clear(&init_mm, addr, (pte_t *)pud); + continue; + } + + pmd_base = (pmd_t *)pud_page_vaddr(*pud); + remove_pmd_table(pmd_base, addr, next); + free_pmd_table(pmd_base, pud); + } +} + +static void remove_pagetable(unsigned long start, unsigned long end) +{ + unsigned long addr, next; + pud_t *pud_base; + pgd_t *pgd; + + spin_lock(&init_mm.page_table_lock); + + for (addr = start; addr < end; addr = next) { + next = pgd_addr_end(addr, end); + + pgd = pgd_offset_k(addr); + if (!pgd_present(*pgd)) + continue; + + if (pgd_huge(*pgd)) { + pte_clear(&init_mm, addr, (pte_t *)pgd); + continue; + } + + pud_base = (pud_t *)pgd_page_vaddr(*pgd); + remove_pud_table(pud_base, addr, next); + } + + spin_unlock(&init_mm.page_table_lock); + radix__flush_tlb_kernel_range(start, end); +} + int __ref radix__create_section_mapping(unsigned long start, unsigned long end) { return create_physical_mapping(start, end); } + +int radix__remove_section_mapping(unsigned long start, unsigned long end) +{ + remove_pagetable(start, end); + return 0; +} #endif /* CONFIG_MEMORY_HOTPLUG */ #ifdef CONFIG_SPARSEMEM_VMEMMAP -- 1.8.3.1