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mm: add default definition of set_ptes()

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Most architectures can just define set_pte() and PFN_PTE_SHIFT to use this
definition.  It's also a handy spot to document the guarantees provided by
the MM.

Link: https://lkml.kernel.org/r/20230802151406.3735276-7-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Suggested-by: Mike Rapoport (IBM) <rppt@kernel.org>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Matthew Wilcox (Oracle) 2023-08-02 16:13:34 +01:00 committed by Andrew Morton
parent 29d26f1215
commit bcc6cc8325
1 changed files with 60 additions and 21 deletions
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81
include/linux/pgtable.h
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@ -182,6 +182,66 @@ static inline int pmd_young(pmd_t pmd)
}
#endif
/*
* A facility to provide lazy MMU batching. This allows PTE updates and
* page invalidations to be delayed until a call to leave lazy MMU mode
* is issued. Some architectures may benefit from doing this, and it is
* beneficial for both shadow and direct mode hypervisors, which may batch
* the PTE updates which happen during this window. Note that using this
* interface requires that read hazards be removed from the code. A read
* hazard could result in the direct mode hypervisor case, since the actual
* write to the page tables may not yet have taken place, so reads though
* a raw PTE pointer after it has been modified are not guaranteed to be
* up to date. This mode can only be entered and left under the protection of
* the page table locks for all page tables which may be modified. In the UP
* case, this is required so that preemption is disabled, and in the SMP case,
* it must synchronize the delayed page table writes properly on other CPUs.
*/
#ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
#define arch_enter_lazy_mmu_mode() do {} while (0)
#define arch_leave_lazy_mmu_mode() do {} while (0)
#define arch_flush_lazy_mmu_mode() do {} while (0)
#endif
#ifndef set_ptes
#ifdef PFN_PTE_SHIFT
/**
* set_ptes - Map consecutive pages to a contiguous range of addresses.
* @mm: Address space to map the pages into.
* @addr: Address to map the first page at.
* @ptep: Page table pointer for the first entry.
* @pte: Page table entry for the first page.
* @nr: Number of pages to map.
*
* May be overridden by the architecture, or the architecture can define
* set_pte() and PFN_PTE_SHIFT.
*
* Context: The caller holds the page table lock. The pages all belong
* to the same folio. The PTEs are all in the same PMD.
*/
static inline void set_ptes(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte, unsigned int nr)
{
page_table_check_ptes_set(mm, ptep, pte, nr);
arch_enter_lazy_mmu_mode();
for (;;) {
set_pte(ptep, pte);
if (--nr == 0)
break;
ptep++;
pte = __pte(pte_val(pte) + (1UL << PFN_PTE_SHIFT));
}
arch_leave_lazy_mmu_mode();
}
#ifndef set_pte_at
#define set_pte_at(mm, addr, ptep, pte) set_ptes(mm, addr, ptep, pte, 1)
#endif
#endif
#else
#define set_pte_at(mm, addr, ptep, pte) set_ptes(mm, addr, ptep, pte, 1)
#endif
#ifndef __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
extern int ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long address, pte_t *ptep,
@ -1051,27 +1111,6 @@ static inline pgprot_t pgprot_modify(pgprot_t oldprot, pgprot_t newprot)
#define pgprot_decrypted(prot) (prot)
#endif
/*
* A facility to provide lazy MMU batching. This allows PTE updates and
* page invalidations to be delayed until a call to leave lazy MMU mode
* is issued. Some architectures may benefit from doing this, and it is
* beneficial for both shadow and direct mode hypervisors, which may batch
* the PTE updates which happen during this window. Note that using this
* interface requires that read hazards be removed from the code. A read
* hazard could result in the direct mode hypervisor case, since the actual
* write to the page tables may not yet have taken place, so reads though
* a raw PTE pointer after it has been modified are not guaranteed to be
* up to date. This mode can only be entered and left under the protection of
* the page table locks for all page tables which may be modified. In the UP
* case, this is required so that preemption is disabled, and in the SMP case,
* it must synchronize the delayed page table writes properly on other CPUs.
*/
#ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
#define arch_enter_lazy_mmu_mode() do {} while (0)
#define arch_leave_lazy_mmu_mode() do {} while (0)
#define arch_flush_lazy_mmu_mode() do {} while (0)
#endif
/*
* A facility to provide batching of the reload of page tables and
* other process state with the actual context switch code for