From 94171b19c3f1f4d9d4c0e3aaa1aa161def1ec7ea Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Thu, 27 Jul 2017 11:54:53 +0530 Subject: [PATCH] powerpc/mm: Rename find_linux_pte_or_hugepte() Add newer helpers to make the function usage simpler. It is always recommended to use find_current_mm_pte() for walking the page table. If we cannot use find_current_mm_pte(), it should be documented why the said usage of __find_linux_pte() is safe against a parallel THP split. For now we have KVM code using __find_linux_pte(). This is because kvm code ends up calling __find_linux_pte() in real mode with MSR_EE=0 but with PACA soft_enabled = 1. We may want to fix that later and make sure we keep the MSR_EE and PACA soft_enabled in sync. When we do that we can switch kvm to use find_linux_pte(). Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman --- arch/powerpc/include/asm/pgtable.h | 10 +------- arch/powerpc/include/asm/pte-walk.h | 35 ++++++++++++++++++++++++++ arch/powerpc/kernel/eeh.c | 4 +-- arch/powerpc/kernel/io-workarounds.c | 5 ++-- arch/powerpc/kvm/book3s_64_mmu_hv.c | 5 ++-- arch/powerpc/kvm/book3s_64_mmu_radix.c | 28 ++++++++++----------- arch/powerpc/kvm/book3s_64_vio_hv.c | 12 ++++++++- arch/powerpc/kvm/book3s_hv_rm_mmu.c | 18 ++++++------- arch/powerpc/kvm/e500_mmu_host.c | 3 ++- arch/powerpc/mm/hash_utils_64.c | 5 ++-- arch/powerpc/mm/hugetlbpage.c | 24 ++++++++++-------- arch/powerpc/mm/tlb_hash64.c | 6 +++-- arch/powerpc/perf/callchain.c | 3 ++- 13 files changed, 103 insertions(+), 55 deletions(-) create mode 100644 arch/powerpc/include/asm/pte-walk.h diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h index afae9a336136..eb9d57defb75 100644 --- a/arch/powerpc/include/asm/pgtable.h +++ b/arch/powerpc/include/asm/pgtable.h @@ -66,16 +66,8 @@ extern int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr, #ifndef CONFIG_TRANSPARENT_HUGEPAGE #define pmd_large(pmd) 0 #endif -pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, - bool *is_thp, unsigned *shift); -static inline pte_t *find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, - bool *is_thp, unsigned *shift) -{ - VM_WARN(!arch_irqs_disabled(), - "%s called with irq enabled\n", __func__); - return __find_linux_pte_or_hugepte(pgdir, ea, is_thp, shift); -} +/* can we use this in kvm */ unsigned long vmalloc_to_phys(void *vmalloc_addr); void pgtable_cache_add(unsigned shift, void (*ctor)(void *)); diff --git a/arch/powerpc/include/asm/pte-walk.h b/arch/powerpc/include/asm/pte-walk.h new file mode 100644 index 000000000000..2d633e9d686c --- /dev/null +++ b/arch/powerpc/include/asm/pte-walk.h @@ -0,0 +1,35 @@ +#ifndef _ASM_POWERPC_PTE_WALK_H +#define _ASM_POWERPC_PTE_WALK_H + +#include + +/* Don't use this directly */ +extern pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, + bool *is_thp, unsigned *hshift); + +static inline pte_t *find_linux_pte(pgd_t *pgdir, unsigned long ea, + bool *is_thp, unsigned *hshift) +{ + VM_WARN(!arch_irqs_disabled(), "%s called with irq enabled\n", __func__); + return __find_linux_pte(pgdir, ea, is_thp, hshift); +} + +static inline pte_t *find_init_mm_pte(unsigned long ea, unsigned *hshift) +{ + pgd_t *pgdir = init_mm.pgd; + return __find_linux_pte(pgdir, ea, NULL, hshift); +} +/* + * This is what we should always use. Any other lockless page table lookup needs + * careful audit against THP split. + */ +static inline pte_t *find_current_mm_pte(pgd_t *pgdir, unsigned long ea, + bool *is_thp, unsigned *hshift) +{ + VM_WARN(!arch_irqs_disabled(), "%s called with irq enabled\n", __func__); + VM_WARN(pgdir != current->mm->pgd, + "%s lock less page table lookup called on wrong mm\n", __func__); + return __find_linux_pte(pgdir, ea, is_thp, hshift); +} + +#endif /* _ASM_POWERPC_PTE_WALK_H */ diff --git a/arch/powerpc/kernel/eeh.c b/arch/powerpc/kernel/eeh.c index 63992b2d8e15..5e6887c40528 100644 --- a/arch/powerpc/kernel/eeh.c +++ b/arch/powerpc/kernel/eeh.c @@ -44,6 +44,7 @@ #include #include #include +#include /** Overview: @@ -352,8 +353,7 @@ static inline unsigned long eeh_token_to_phys(unsigned long token) * worried about _PAGE_SPLITTING/collapse. Also we will not hit * page table free, because of init_mm. */ - ptep = __find_linux_pte_or_hugepte(init_mm.pgd, token, - NULL, &hugepage_shift); + ptep = find_init_mm_pte(token, &hugepage_shift); if (!ptep) return token; WARN_ON(hugepage_shift); diff --git a/arch/powerpc/kernel/io-workarounds.c b/arch/powerpc/kernel/io-workarounds.c index a582e0d42525..bbe85f5aea71 100644 --- a/arch/powerpc/kernel/io-workarounds.c +++ b/arch/powerpc/kernel/io-workarounds.c @@ -19,6 +19,8 @@ #include #include #include +#include + #define IOWA_MAX_BUS 8 @@ -75,8 +77,7 @@ struct iowa_bus *iowa_mem_find_bus(const PCI_IO_ADDR addr) * We won't find huge pages here (iomem). Also can't hit * a page table free due to init_mm */ - ptep = __find_linux_pte_or_hugepte(init_mm.pgd, vaddr, - NULL, &hugepage_shift); + ptep = find_init_mm_pte(vaddr, &hugepage_shift); if (ptep == NULL) paddr = 0; else { diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 8cb0190e2a73..4b219db39c47 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -37,6 +37,7 @@ #include #include #include +#include #include "trace_hv.h" @@ -597,8 +598,8 @@ int kvmppc_book3s_hv_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, * hugepage split and collapse. */ local_irq_save(flags); - ptep = find_linux_pte_or_hugepte(current->mm->pgd, - hva, NULL, NULL); + ptep = find_current_mm_pte(current->mm->pgd, + hva, NULL, NULL); if (ptep) { pte = kvmppc_read_update_linux_pte(ptep, 1); if (__pte_write(pte)) diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c index f6b3e67c5762..7d719c8aa0bb 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -17,6 +17,7 @@ #include #include #include +#include /* * Supported radix tree geometry. @@ -359,8 +360,7 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, if (writing) pgflags |= _PAGE_DIRTY; local_irq_save(flags); - ptep = __find_linux_pte_or_hugepte(current->mm->pgd, hva, - NULL, NULL); + ptep = find_current_mm_pte(current->mm->pgd, hva, NULL, NULL); if (ptep) { pte = READ_ONCE(*ptep); if (pte_present(pte) && @@ -374,8 +374,12 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, spin_unlock(&kvm->mmu_lock); return RESUME_GUEST; } - ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, - gpa, NULL, &shift); + /* + * We are walking the secondary page table here. We can do this + * without disabling irq. + */ + ptep = __find_linux_pte(kvm->arch.pgtable, + gpa, NULL, &shift); if (ptep && pte_present(*ptep)) { kvmppc_radix_update_pte(kvm, ptep, 0, pgflags, gpa, shift); @@ -427,8 +431,8 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu, pgflags |= _PAGE_WRITE; } else { local_irq_save(flags); - ptep = __find_linux_pte_or_hugepte(current->mm->pgd, - hva, NULL, NULL); + ptep = find_current_mm_pte(current->mm->pgd, + hva, NULL, NULL); if (ptep && pte_write(*ptep) && pte_dirty(*ptep)) pgflags |= _PAGE_WRITE; local_irq_restore(flags); @@ -499,8 +503,7 @@ int kvm_unmap_radix(struct kvm *kvm, struct kvm_memory_slot *memslot, unsigned int shift; unsigned long old; - ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa, - NULL, &shift); + ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (ptep && pte_present(*ptep)) { old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_PRESENT, 0, gpa, shift); @@ -525,8 +528,7 @@ int kvm_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot, unsigned int shift; int ref = 0; - ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa, - NULL, &shift); + ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (ptep && pte_present(*ptep) && pte_young(*ptep)) { kvmppc_radix_update_pte(kvm, ptep, _PAGE_ACCESSED, 0, gpa, shift); @@ -545,8 +547,7 @@ int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot, unsigned int shift; int ref = 0; - ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa, - NULL, &shift); + ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (ptep && pte_present(*ptep) && pte_young(*ptep)) ref = 1; return ref; @@ -562,8 +563,7 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm, unsigned int shift; int ret = 0; - ptep = __find_linux_pte_or_hugepte(kvm->arch.pgtable, gpa, - NULL, &shift); + ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift); if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) { ret = 1; if (shift) diff --git a/arch/powerpc/kvm/book3s_64_vio_hv.c b/arch/powerpc/kvm/book3s_64_vio_hv.c index 3adfd2f5301c..c32e9bfe75b1 100644 --- a/arch/powerpc/kvm/book3s_64_vio_hv.c +++ b/arch/powerpc/kvm/book3s_64_vio_hv.c @@ -39,6 +39,7 @@ #include #include #include +#include #ifdef CONFIG_BUG @@ -353,7 +354,16 @@ static long kvmppc_rm_ua_to_hpa(struct kvm_vcpu *vcpu, pte_t *ptep, pte; unsigned shift = 0; - ptep = __find_linux_pte_or_hugepte(vcpu->arch.pgdir, ua, NULL, &shift); + /* + * Called in real mode with MSR_EE = 0. We are safe here. + * It is ok to do the lookup with arch.pgdir here, because + * we are doing this on secondary cpus and current task there + * is not the hypervisor. Also this is safe against THP in the + * host, because an IPI to primary thread will wait for the secondary + * to exit which will agains result in the below page table walk + * to finish. + */ + ptep = __find_linux_pte(vcpu->arch.pgdir, ua, NULL, &shift); if (!ptep || !pte_present(*ptep)) return -ENXIO; pte = *ptep; diff --git a/arch/powerpc/kvm/book3s_hv_rm_mmu.c b/arch/powerpc/kvm/book3s_hv_rm_mmu.c index 584c74c8119f..fedb0139524c 100644 --- a/arch/powerpc/kvm/book3s_hv_rm_mmu.c +++ b/arch/powerpc/kvm/book3s_hv_rm_mmu.c @@ -22,6 +22,7 @@ #include #include #include +#include /* Translate address of a vmalloc'd thing to a linear map address */ static void *real_vmalloc_addr(void *x) @@ -31,9 +32,9 @@ static void *real_vmalloc_addr(void *x) /* * assume we don't have huge pages in vmalloc space... * So don't worry about THP collapse/split. Called - * Only in realmode, hence won't need irq_save/restore. + * Only in realmode with MSR_EE = 0, hence won't need irq_save/restore. */ - p = __find_linux_pte_or_hugepte(swapper_pg_dir, addr, NULL, NULL); + p = find_init_mm_pte(addr, NULL); if (!p || !pte_present(*p)) return NULL; addr = (pte_pfn(*p) << PAGE_SHIFT) | (addr & ~PAGE_MASK); @@ -230,14 +231,13 @@ long kvmppc_do_h_enter(struct kvm *kvm, unsigned long flags, * If we had a page table table change after lookup, we would * retry via mmu_notifier_retry. */ - if (realmode) - ptep = __find_linux_pte_or_hugepte(pgdir, hva, NULL, - &hpage_shift); - else { + if (!realmode) local_irq_save(irq_flags); - ptep = find_linux_pte_or_hugepte(pgdir, hva, NULL, - &hpage_shift); - } + /* + * If called in real mode we have MSR_EE = 0. Otherwise + * we disable irq above. + */ + ptep = __find_linux_pte(pgdir, hva, NULL, &hpage_shift); if (ptep) { pte_t pte; unsigned int host_pte_size; diff --git a/arch/powerpc/kvm/e500_mmu_host.c b/arch/powerpc/kvm/e500_mmu_host.c index 77fd043b3ecc..c6c734424c70 100644 --- a/arch/powerpc/kvm/e500_mmu_host.c +++ b/arch/powerpc/kvm/e500_mmu_host.c @@ -30,6 +30,7 @@ #include #include #include +#include #include "e500.h" #include "timing.h" @@ -476,7 +477,7 @@ static inline int kvmppc_e500_shadow_map(struct kvmppc_vcpu_e500 *vcpu_e500, * can't run hence pfn won't change. */ local_irq_save(flags); - ptep = find_linux_pte_or_hugepte(pgdir, hva, NULL, NULL); + ptep = find_linux_pte(pgdir, hva, NULL, NULL); if (ptep) { pte_t pte = READ_ONCE(*ptep); diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index 7a20669c19e7..5b10b4fcbf76 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -61,6 +61,7 @@ #include #include #include +#include #ifdef DEBUG #define DBG(fmt...) udbg_printf(fmt) @@ -1297,7 +1298,7 @@ int hash_page_mm(struct mm_struct *mm, unsigned long ea, #endif /* CONFIG_PPC_64K_PAGES */ /* Get PTE and page size from page tables */ - ptep = __find_linux_pte_or_hugepte(pgdir, ea, &is_thp, &hugeshift); + ptep = find_linux_pte(pgdir, ea, &is_thp, &hugeshift); if (ptep == NULL || !pte_present(*ptep)) { DBG_LOW(" no PTE !\n"); rc = 1; @@ -1526,7 +1527,7 @@ void hash_preload(struct mm_struct *mm, unsigned long ea, * THP pages use update_mmu_cache_pmd. We don't do * hash preload there. Hence can ignore THP here */ - ptep = find_linux_pte_or_hugepte(pgdir, ea, NULL, &hugepage_shift); + ptep = find_current_mm_pte(pgdir, ea, NULL, &hugepage_shift); if (!ptep) goto out_exit; diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c index e1bf5ca397fe..70a3a2bdf06c 100644 --- a/arch/powerpc/mm/hugetlbpage.c +++ b/arch/powerpc/mm/hugetlbpage.c @@ -24,6 +24,8 @@ #include #include #include +#include + #ifdef CONFIG_HUGETLB_PAGE @@ -60,8 +62,11 @@ static unsigned nr_gpages; pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz) { - /* Only called for hugetlbfs pages, hence can ignore THP */ - return __find_linux_pte_or_hugepte(mm->pgd, addr, NULL, NULL); + /* + * Only called for hugetlbfs pages, hence can ignore THP and the + * irq disabled walk. + */ + return __find_linux_pte(mm->pgd, addr, NULL, NULL); } static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp, @@ -886,9 +891,8 @@ void flush_dcache_icache_hugepage(struct page *page) * This function need to be called with interrupts disabled. We use this variant * when we have MSR[EE] = 0 but the paca->soft_enabled = 1 */ - -pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, - bool *is_thp, unsigned *shift) +pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea, + bool *is_thp, unsigned *hpage_shift) { pgd_t pgd, *pgdp; pud_t pud, *pudp; @@ -897,8 +901,8 @@ pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, hugepd_t *hpdp = NULL; unsigned pdshift = PGDIR_SHIFT; - if (shift) - *shift = 0; + if (hpage_shift) + *hpage_shift = 0; if (is_thp) *is_thp = false; @@ -968,11 +972,11 @@ pte_t *__find_linux_pte_or_hugepte(pgd_t *pgdir, unsigned long ea, ret_pte = hugepte_offset(*hpdp, ea, pdshift); pdshift = hugepd_shift(*hpdp); out: - if (shift) - *shift = pdshift; + if (hpage_shift) + *hpage_shift = pdshift; return ret_pte; } -EXPORT_SYMBOL_GPL(__find_linux_pte_or_hugepte); +EXPORT_SYMBOL_GPL(__find_linux_pte); int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr, unsigned long end, int write, struct page **pages, int *nr) diff --git a/arch/powerpc/mm/tlb_hash64.c b/arch/powerpc/mm/tlb_hash64.c index b5b0fb97b9c0..71cb2742bd16 100644 --- a/arch/powerpc/mm/tlb_hash64.c +++ b/arch/powerpc/mm/tlb_hash64.c @@ -29,6 +29,8 @@ #include #include #include +#include + #include @@ -207,8 +209,8 @@ void __flush_hash_table_range(struct mm_struct *mm, unsigned long start, local_irq_save(flags); arch_enter_lazy_mmu_mode(); for (; start < end; start += PAGE_SIZE) { - pte_t *ptep = find_linux_pte_or_hugepte(mm->pgd, start, &is_thp, - &hugepage_shift); + pte_t *ptep = find_current_mm_pte(mm->pgd, start, &is_thp, + &hugepage_shift); unsigned long pte; if (ptep == NULL) diff --git a/arch/powerpc/perf/callchain.c b/arch/powerpc/perf/callchain.c index 0fc26714780a..0af051a1974e 100644 --- a/arch/powerpc/perf/callchain.c +++ b/arch/powerpc/perf/callchain.c @@ -22,6 +22,7 @@ #ifdef CONFIG_PPC64 #include "../kernel/ppc32.h" #endif +#include /* @@ -127,7 +128,7 @@ static int read_user_stack_slow(void __user *ptr, void *buf, int nb) return -EFAULT; local_irq_save(flags); - ptep = find_linux_pte_or_hugepte(pgdir, addr, NULL, &shift); + ptep = find_current_mm_pte(pgdir, addr, NULL, &shift); if (!ptep) goto err_out; if (!shift) -- 2.20.1