Re: [PATCH v2 18/30] powerpc: Implement the new page table range API

From: Christophe Leroy
Date: Mon Feb 27 2023 - 14:45:47 EST

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In reply to: Matthew Wilcox (Oracle): "[PATCH v2 18/30] powerpc: Implement the new page table range API"
Next in thread: Matthew Wilcox: "Re: [PATCH v2 18/30] powerpc: Implement the new page table range API"
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Hi,

Le 27/02/2023 à 18:57, Matthew Wilcox (Oracle) a écrit :
> Add set_ptes(), update_mmu_cache_range() and flush_dcache_folio().
> Change the PG_arch_1 (aka PG_dcache_dirty) flag from being per-page to
> per-folio.
>
> I'm unsure about my merging of flush_dcache_icache_hugepage() and
> flush_dcache_icache_page() into flush_dcache_icache_folio() and subsequent
> removal of flush_dcache_icache_phys(). Please review.

Not sure why you want to remove flush_dcache_icache_phys().

Allthough that's only feasible when address bus is not wider than 32
bits and cannot be done on BOOKE as you can't switch off MMU on BOOKE,
flush_dcache_icache_phys() allows to flush not mapped pages without
having to map them. So it is more efficient.

Christophe

>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
> Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
> Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx
> ---
> arch/powerpc/include/asm/book3s/pgtable.h | 10 +--
> arch/powerpc/include/asm/cacheflush.h | 14 ++--
> arch/powerpc/include/asm/kvm_ppc.h | 10 +--
> arch/powerpc/include/asm/nohash/pgtable.h | 13 ++--
> arch/powerpc/include/asm/pgtable.h | 6 ++
> arch/powerpc/mm/book3s64/hash_utils.c | 11 +--
> arch/powerpc/mm/cacheflush.c | 81 +++--------------------
> arch/powerpc/mm/nohash/e500_hugetlbpage.c | 3 +-
> arch/powerpc/mm/pgtable.c | 51 ++++++++------
> 9 files changed, 73 insertions(+), 126 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/book3s/pgtable.h b/arch/powerpc/include/asm/book3s/pgtable.h
> index d18b748ea3ae..c2ef811505b0 100644
> --- a/arch/powerpc/include/asm/book3s/pgtable.h
> +++ b/arch/powerpc/include/asm/book3s/pgtable.h
> @@ -9,13 +9,6 @@
> #endif
>
> #ifndef __ASSEMBLY__
> -/* Insert a PTE, top-level function is out of line. It uses an inline
> - * low level function in the respective pgtable-* files
> - */
> -extern void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
> - pte_t pte);
> -
> -
> #define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS
> extern int ptep_set_access_flags(struct vm_area_struct *vma, unsigned long address,
> pte_t *ptep, pte_t entry, int dirty);
> @@ -36,7 +29,8 @@ void __update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t
> * corresponding HPTE into the hash table ahead of time, instead of
> * waiting for the inevitable extra hash-table miss exception.
> */
> -static inline void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
> +static inline void update_mmu_cache_range(struct vm_area_struct *vma,
> + unsigned long address, pte_t *ptep, unsigned int nr)
> {
> if (IS_ENABLED(CONFIG_PPC32) && !mmu_has_feature(MMU_FTR_HPTE_TABLE))
> return;
> diff --git a/arch/powerpc/include/asm/cacheflush.h b/arch/powerpc/include/asm/cacheflush.h
> index 7564dd4fd12b..ef7d2de33b89 100644
> --- a/arch/powerpc/include/asm/cacheflush.h
> +++ b/arch/powerpc/include/asm/cacheflush.h
> @@ -35,13 +35,19 @@ static inline void flush_cache_vmap(unsigned long start, unsigned long end)
> * It just marks the page as not i-cache clean. We do the i-cache
> * flush later when the page is given to a user process, if necessary.
> */
> -static inline void flush_dcache_page(struct page *page)
> +static inline void flush_dcache_folio(struct folio *folio)
> {
> if (cpu_has_feature(CPU_FTR_COHERENT_ICACHE))
> return;
> /* avoid an atomic op if possible */
> - if (test_bit(PG_dcache_clean, &page->flags))
> - clear_bit(PG_dcache_clean, &page->flags);
> + if (test_bit(PG_dcache_clean, &folio->flags))
> + clear_bit(PG_dcache_clean, &folio->flags);
> +}
> +#define flush_dcache_folio flush_dcache_folio
> +
> +static inline void flush_dcache_page(struct page *page)
> +{
> + flush_dcache_folio(page_folio(page));
> }
>
> void flush_icache_range(unsigned long start, unsigned long stop);
> @@ -51,7 +57,7 @@ void flush_icache_user_page(struct vm_area_struct *vma, struct page *page,
> unsigned long addr, int len);
> #define flush_icache_user_page flush_icache_user_page
>
> -void flush_dcache_icache_page(struct page *page);
> +void flush_dcache_icache_folio(struct folio *folio);
>
> /**
> * flush_dcache_range(): Write any modified data cache blocks out to memory and
> diff --git a/arch/powerpc/include/asm/kvm_ppc.h b/arch/powerpc/include/asm/kvm_ppc.h
> index 6bef23d6d0e3..e91dd8e88bb7 100644
> --- a/arch/powerpc/include/asm/kvm_ppc.h
> +++ b/arch/powerpc/include/asm/kvm_ppc.h
> @@ -868,7 +868,7 @@ void kvmppc_init_lpid(unsigned long nr_lpids);
>
> static inline void kvmppc_mmu_flush_icache(kvm_pfn_t pfn)
> {
> - struct page *page;
> + struct folio *folio;
> /*
> * We can only access pages that the kernel maps
> * as memory. Bail out for unmapped ones.
> @@ -877,10 +877,10 @@ static inline void kvmppc_mmu_flush_icache(kvm_pfn_t pfn)
> return;
>
> /* Clear i-cache for new pages */
> - page = pfn_to_page(pfn);
> - if (!test_bit(PG_dcache_clean, &page->flags)) {
> - flush_dcache_icache_page(page);
> - set_bit(PG_dcache_clean, &page->flags);
> + folio = page_folio(pfn_to_page(pfn));
> + if (!test_bit(PG_dcache_clean, &folio->flags)) {
> + flush_dcache_icache_folio(folio);
> + set_bit(PG_dcache_clean, &folio->flags);
> }
> }
>
> diff --git a/arch/powerpc/include/asm/nohash/pgtable.h b/arch/powerpc/include/asm/nohash/pgtable.h
> index a6caaaab6f92..69a7dd47a9f0 100644
> --- a/arch/powerpc/include/asm/nohash/pgtable.h
> +++ b/arch/powerpc/include/asm/nohash/pgtable.h
> @@ -166,12 +166,6 @@ static inline pte_t pte_swp_clear_exclusive(pte_t pte)
> return __pte(pte_val(pte) & ~_PAGE_SWP_EXCLUSIVE);
> }
>
> -/* Insert a PTE, top-level function is out of line. It uses an inline
> - * low level function in the respective pgtable-* files
> - */
> -extern void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
> - pte_t pte);
> -
> /* This low level function performs the actual PTE insertion
> * Setting the PTE depends on the MMU type and other factors. It's
> * an horrible mess that I'm not going to try to clean up now but
> @@ -282,10 +276,11 @@ static inline int pud_huge(pud_t pud)
> * for the page which has just been mapped in.
> */
> #if defined(CONFIG_PPC_E500) && defined(CONFIG_HUGETLB_PAGE)
> -void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *ptep);
> +void update_mmu_cache_range(struct vm_area_struct *vma, unsigned long address,
> + pte_t *ptep, unsigned int nr);
> #else
> -static inline
> -void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *ptep) {}
> +static inline void update_mmu_cache(struct vm_area_struct *vma,
> + unsigned long address, pte_t *ptep, unsigned int nr) {}
> #endif
>
> #endif /* __ASSEMBLY__ */
> diff --git a/arch/powerpc/include/asm/pgtable.h b/arch/powerpc/include/asm/pgtable.h
> index 9972626ddaf6..bf1263ff7e67 100644
> --- a/arch/powerpc/include/asm/pgtable.h
> +++ b/arch/powerpc/include/asm/pgtable.h
> @@ -41,6 +41,12 @@ struct mm_struct;
>
> #ifndef __ASSEMBLY__
>
> +void set_ptes(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
> + pte_t pte, unsigned int nr);
> +#define set_pte_at(mm, addr, ptep, pte) set_ptes(mm, addr, ptep, pte, 1)
> +#define update_mmu_cache(vma, addr, ptep) \
> + update_mmu_cache_range(vma, addr, ptep, 1);
> +
> #ifndef MAX_PTRS_PER_PGD
> #define MAX_PTRS_PER_PGD PTRS_PER_PGD
> #endif
> diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
> index fedffe3ae136..ad2afa08e62e 100644
> --- a/arch/powerpc/mm/book3s64/hash_utils.c
> +++ b/arch/powerpc/mm/book3s64/hash_utils.c
> @@ -1307,18 +1307,19 @@ void hash__early_init_mmu_secondary(void)
> */
> unsigned int hash_page_do_lazy_icache(unsigned int pp, pte_t pte, int trap)
> {
> - struct page *page;
> + struct folio *folio;
>
> if (!pfn_valid(pte_pfn(pte)))
> return pp;
>
> - page = pte_page(pte);
> + folio = page_folio(pte_page(pte));
>
> /* page is dirty */
> - if (!test_bit(PG_dcache_clean, &page->flags) && !PageReserved(page)) {
> + if (!test_bit(PG_dcache_clean, &folio->flags) &&
> + !folio_test_reserved(folio)) {
> if (trap == INTERRUPT_INST_STORAGE) {
> - flush_dcache_icache_page(page);
> - set_bit(PG_dcache_clean, &page->flags);
> + flush_dcache_icache_folio(folio);
> + set_bit(PG_dcache_clean, &folio->flags);
> } else
> pp |= HPTE_R_N;
> }
> diff --git a/arch/powerpc/mm/cacheflush.c b/arch/powerpc/mm/cacheflush.c
> index 0e9b4879c0f9..8ea6a096a664 100644
> --- a/arch/powerpc/mm/cacheflush.c
> +++ b/arch/powerpc/mm/cacheflush.c
> @@ -76,51 +76,6 @@ void flush_icache_range(unsigned long start, unsigned long stop)
> }
> EXPORT_SYMBOL(flush_icache_range);
>
> -#ifdef CONFIG_HIGHMEM
> -/**
> - * flush_dcache_icache_phys() - Flush a page by it's physical address
> - * @physaddr: the physical address of the page
> - */
> -static void flush_dcache_icache_phys(unsigned long physaddr)
> -{
> - unsigned long bytes = l1_dcache_bytes();
> - unsigned long nb = PAGE_SIZE / bytes;
> - unsigned long addr = physaddr & PAGE_MASK;
> - unsigned long msr, msr0;
> - unsigned long loop1 = addr, loop2 = addr;
> -
> - msr0 = mfmsr();
> - msr = msr0 & ~MSR_DR;
> - /*
> - * This must remain as ASM to prevent potential memory accesses
> - * while the data MMU is disabled
> - */
> - asm volatile(
> - " mtctr %2;\n"
> - " mtmsr %3;\n"
> - " isync;\n"
> - "0: dcbst 0, %0;\n"
> - " addi %0, %0, %4;\n"
> - " bdnz 0b;\n"
> - " sync;\n"
> - " mtctr %2;\n"
> - "1: icbi 0, %1;\n"
> - " addi %1, %1, %4;\n"
> - " bdnz 1b;\n"
> - " sync;\n"
> - " mtmsr %5;\n"
> - " isync;\n"
> - : "+&r" (loop1), "+&r" (loop2)
> - : "r" (nb), "r" (msr), "i" (bytes), "r" (msr0)
> - : "ctr", "memory");
> -}
> -NOKPROBE_SYMBOL(flush_dcache_icache_phys)
> -#else
> -static void flush_dcache_icache_phys(unsigned long physaddr)
> -{
> -}
> -#endif
> -
> /**
> * __flush_dcache_icache(): Flush a particular page from the data cache to RAM.
> * Note: this is necessary because the instruction cache does *not*
> @@ -148,17 +103,20 @@ static void __flush_dcache_icache(void *p)
> invalidate_icache_range(addr, addr + PAGE_SIZE);
> }
>
> -static void flush_dcache_icache_hugepage(struct page *page)
> +void flush_dcache_icache_folio(struct folio *folio)
> {
> - int i;
> - int nr = compound_nr(page);
> + unsigned int i, nr = folio_nr_pages(folio);
>
> - if (!PageHighMem(page)) {
> + if (flush_coherent_icache())
> + return;
> +
> + if (!folio_test_highmem(folio)) {
> + void *addr = folio_address(folio);
> for (i = 0; i < nr; i++)
> - __flush_dcache_icache(lowmem_page_address(page + i));
> + __flush_dcache_icache(addr + i * PAGE_SIZE);
> } else {
> for (i = 0; i < nr; i++) {
> - void *start = kmap_local_page(page + i);
> + void *start = kmap_local_folio(folio, i * PAGE_SIZE);
>
> __flush_dcache_icache(start);
> kunmap_local(start);
> @@ -166,27 +124,6 @@ static void flush_dcache_icache_hugepage(struct page *page)
> }
> }
>
> -void flush_dcache_icache_page(struct page *page)
> -{
> - if (flush_coherent_icache())
> - return;
> -
> - if (PageCompound(page))
> - return flush_dcache_icache_hugepage(page);
> -
> - if (!PageHighMem(page)) {
> - __flush_dcache_icache(lowmem_page_address(page));
> - } else if (IS_ENABLED(CONFIG_BOOKE) || sizeof(phys_addr_t) > sizeof(void *)) {
> - void *start = kmap_local_page(page);
> -
> - __flush_dcache_icache(start);
> - kunmap_local(start);
> - } else {
> - flush_dcache_icache_phys(page_to_phys(page));
> - }
> -}
> -EXPORT_SYMBOL(flush_dcache_icache_page);
> -
> void clear_user_page(void *page, unsigned long vaddr, struct page *pg)
> {
> clear_page(page);
> diff --git a/arch/powerpc/mm/nohash/e500_hugetlbpage.c b/arch/powerpc/mm/nohash/e500_hugetlbpage.c
> index 58c8d9849cb1..f3cb91107a47 100644
> --- a/arch/powerpc/mm/nohash/e500_hugetlbpage.c
> +++ b/arch/powerpc/mm/nohash/e500_hugetlbpage.c
> @@ -178,7 +178,8 @@ book3e_hugetlb_preload(struct vm_area_struct *vma, unsigned long ea, pte_t pte)
> *
> * This must always be called with the pte lock held.
> */
> -void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *ptep)
> +void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
> + pte_t *ptep, unsigned int nr)
> {
> if (is_vm_hugetlb_page(vma))
> book3e_hugetlb_preload(vma, address, *ptep);
> diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
> index cb2dcdb18f8e..b3c7b874a7a2 100644
> --- a/arch/powerpc/mm/pgtable.c
> +++ b/arch/powerpc/mm/pgtable.c
> @@ -58,7 +58,7 @@ static inline int pte_looks_normal(pte_t pte)
> return 0;
> }
>
> -static struct page *maybe_pte_to_page(pte_t pte)
> +static struct folio *maybe_pte_to_folio(pte_t pte)
> {
> unsigned long pfn = pte_pfn(pte);
> struct page *page;
> @@ -68,7 +68,7 @@ static struct page *maybe_pte_to_page(pte_t pte)
> page = pfn_to_page(pfn);
> if (PageReserved(page))
> return NULL;
> - return page;
> + return page_folio(page);
> }
>
> #ifdef CONFIG_PPC_BOOK3S
> @@ -84,12 +84,12 @@ static pte_t set_pte_filter_hash(pte_t pte)
> pte = __pte(pte_val(pte) & ~_PAGE_HPTEFLAGS);
> if (pte_looks_normal(pte) && !(cpu_has_feature(CPU_FTR_COHERENT_ICACHE) ||
> cpu_has_feature(CPU_FTR_NOEXECUTE))) {
> - struct page *pg = maybe_pte_to_page(pte);
> - if (!pg)
> + struct folio *folio = maybe_pte_to_folio(pte);
> + if (!folio)
> return pte;
> - if (!test_bit(PG_dcache_clean, &pg->flags)) {
> - flush_dcache_icache_page(pg);
> - set_bit(PG_dcache_clean, &pg->flags);
> + if (!test_bit(PG_dcache_clean, &folio->flags)) {
> + flush_dcache_icache_folio(folio);
> + set_bit(PG_dcache_clean, &folio->flags);
> }
> }
> return pte;
> @@ -107,7 +107,7 @@ static pte_t set_pte_filter_hash(pte_t pte) { return pte; }
> */
> static inline pte_t set_pte_filter(pte_t pte)
> {
> - struct page *pg;
> + struct folio *folio;
>
> if (radix_enabled())
> return pte;
> @@ -120,18 +120,18 @@ static inline pte_t set_pte_filter(pte_t pte)
> return pte;
>
> /* If you set _PAGE_EXEC on weird pages you're on your own */
> - pg = maybe_pte_to_page(pte);
> - if (unlikely(!pg))
> + folio = maybe_pte_to_folio(pte);
> + if (unlikely(!folio))
> return pte;
>
> /* If the page clean, we move on */
> - if (test_bit(PG_dcache_clean, &pg->flags))
> + if (test_bit(PG_dcache_clean, &folio->flags))
> return pte;
>
> /* If it's an exec fault, we flush the cache and make it clean */
> if (is_exec_fault()) {
> - flush_dcache_icache_page(pg);
> - set_bit(PG_dcache_clean, &pg->flags);
> + flush_dcache_icache_folio(folio);
> + set_bit(PG_dcache_clean, &folio->flags);
> return pte;
> }
>
> @@ -142,7 +142,7 @@ static inline pte_t set_pte_filter(pte_t pte)
> static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
> int dirty)
> {
> - struct page *pg;
> + struct folio *folio;
>
> if (IS_ENABLED(CONFIG_PPC_BOOK3S_64))
> return pte;
> @@ -168,17 +168,17 @@ static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
> #endif /* CONFIG_DEBUG_VM */
>
> /* If you set _PAGE_EXEC on weird pages you're on your own */
> - pg = maybe_pte_to_page(pte);
> - if (unlikely(!pg))
> + folio = maybe_pte_to_folio(pte);
> + if (unlikely(!folio))
> goto bail;
>
> /* If the page is already clean, we move on */
> - if (test_bit(PG_dcache_clean, &pg->flags))
> + if (test_bit(PG_dcache_clean, &folio->flags))
> goto bail;
>
> /* Clean the page and set PG_dcache_clean */
> - flush_dcache_icache_page(pg);
> - set_bit(PG_dcache_clean, &pg->flags);
> + flush_dcache_icache_folio(folio);
> + set_bit(PG_dcache_clean, &folio->flags);
>
> bail:
> return pte_mkexec(pte);
> @@ -187,8 +187,8 @@ static pte_t set_access_flags_filter(pte_t pte, struct vm_area_struct *vma,
> /*
> * set_pte stores a linux PTE into the linux page table.
> */
> -void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
> - pte_t pte)
> +void set_ptes(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
> + pte_t pte, unsigned int nr)
> {
> /*
> * Make sure hardware valid bit is not set. We don't do
> @@ -203,7 +203,14 @@ void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
> pte = set_pte_filter(pte);
>
> /* Perform the setting of the PTE */
> - __set_pte_at(mm, addr, ptep, pte, 0);
> + for (;;) {
> + __set_pte_at(mm, addr, ptep, pte, 0);
> + if (--nr == 0)
> + break;
> + ptep++;
> + pte = __pte(pte_val(pte) + PAGE_SIZE);
> + addr += PAGE_SIZE;
> + }
> }
>
> void unmap_kernel_page(unsigned long va)

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