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From:   Atish Patra <atishp@atishpatra.org>
Date:   Fri, 14 Aug 2020 09:50:10 -0700
Message-ID: <CAOnJCU+aJKnssfXr4O1+s=yo2txxEqu9xFGf9u8XTWJnav+cNA@mail.gmail.com>
Subject: Re: [PATCH v5 3/9] RISC-V: Implement late mapping page table
 allocation functions
To:     Mike Rapoport <rppt@kernel.org>
Cc:     Atish Patra <atish.patra@wdc.com>,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Alistair Francis <alistair.francis@wdc.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Anup Patel <anup.patel@wdc.com>,
        Ard Biesheuvel <ardb@kernel.org>,
        Arvind Sankar <nivedita@alum.mit.edu>,
        Borislav Petkov <bp@suse.de>,
        Greentime Hu <greentime.hu@sifive.com>,
        Ingo Molnar <mingo@kernel.org>,
        Kees Cook <keescook@chromium.org>,
        linux-efi <linux-efi@vger.kernel.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        fwts-devel@lists.ubuntu.com, Mao Han <han_mao@c-sky.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Michal Simek <michal.simek@xilinx.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Steven Price <steven.price@arm.com>,
        Waiman Long <longman@redhat.com>,
        Will Deacon <will@kernel.org>,
        Daniel Schaefer <daniel.schaefer@hpe.com>,
        "abner.chang@hpe.com" <abner.chang@hpe.com>
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On Fri, Aug 14, 2020 at 2:39 AM Mike Rapoport <rppt@kernel.org> wrote:
>
> On Wed, Aug 12, 2020 at 04:47:52PM -0700, Atish Patra wrote:
> > Currently, page table setup is done during setup_va_final where fixmap can
> > be used to create the temporary mappings. The physical frame is allocated
> > from memblock_alloc_* functions. However, this won't work if page table
> > mapping needs to be created for a different mm context (i.e. efi mm) at
> > a later point of time.
> >
> > Use generic kernel page allocation function & macros for any mapping
> > after setup_vm_final.
> >
> > Signed-off-by: Atish Patra <atish.patra@wdc.com>
>
> A nit below, otherwise
>
>
> Acked-by: Mike Rapoport <rppt@linux.ibm.com>
>
> > ---
> >  arch/riscv/mm/init.c | 130 ++++++++++++++++++++++++++++++++-----------
> >  1 file changed, 99 insertions(+), 31 deletions(-)
> >
> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > index b75ebe8e7a92..d238cdc501ee 100644
> > --- a/arch/riscv/mm/init.c
> > +++ b/arch/riscv/mm/init.c
> > @@ -32,6 +32,17 @@ extern char _start[];
> >  void *dtb_early_va __initdata;
> >  uintptr_t dtb_early_pa __initdata;
> >
> > +struct pt_alloc_ops {
> > +     pte_t *(*get_pte_virt)(phys_addr_t pa);
> > +     phys_addr_t (*alloc_pte)(uintptr_t va);
> > +#ifndef __PAGETABLE_PMD_FOLDED
> > +     pmd_t *(*get_pmd_virt)(phys_addr_t pa);
> > +     phys_addr_t (*alloc_pmd)(uintptr_t va);
> > +#endif
> > +};
> > +
> > +struct pt_alloc_ops pt_ops;
>
> static?
>

Ahh yes. Thanks for catching that. I will fix it in the next version.

> > +
> >  static void __init zone_sizes_init(void)
> >  {
> >       unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
> > @@ -211,7 +222,6 @@ EXPORT_SYMBOL(pfn_base);
> >  pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
> >  pgd_t trampoline_pg_dir[PTRS_PER_PGD] __page_aligned_bss;
> >  pte_t fixmap_pte[PTRS_PER_PTE] __page_aligned_bss;
> > -static bool mmu_enabled;
> >
> >  #define MAX_EARLY_MAPPING_SIZE       SZ_128M
> >
> > @@ -234,27 +244,46 @@ void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
> >       }
> >  }
> >
> > -static pte_t *__init get_pte_virt(phys_addr_t pa)
> > +static inline pte_t *__init get_pte_virt_early(phys_addr_t pa)
> >  {
> > -     if (mmu_enabled) {
> > -             clear_fixmap(FIX_PTE);
> > -             return (pte_t *)set_fixmap_offset(FIX_PTE, pa);
> > -     } else {
> > -             return (pte_t *)((uintptr_t)pa);
> > -     }
> > +     return (pte_t *)((uintptr_t)pa);
> >  }
> >
> > -static phys_addr_t __init alloc_pte(uintptr_t va)
> > +static inline pte_t *__init get_pte_virt_fixmap(phys_addr_t pa)
> > +{
> > +     clear_fixmap(FIX_PTE);
> > +     return (pte_t *)set_fixmap_offset(FIX_PTE, pa);
> > +}
> > +
> > +static inline pte_t *get_pte_virt_late(phys_addr_t pa)
> > +{
> > +     return (pte_t *) __va(pa);
> > +}
> > +
> > +static inline phys_addr_t __init alloc_pte_early(uintptr_t va)
> >  {
> >       /*
> >        * We only create PMD or PGD early mappings so we
> >        * should never reach here with MMU disabled.
> >        */
> > -     BUG_ON(!mmu_enabled);
> > +     BUG();
> > +}
> >
> > +static inline phys_addr_t __init alloc_pte_fixmap(uintptr_t va)
> > +{
> >       return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
> >  }
> >
> > +static phys_addr_t alloc_pte_late(uintptr_t va)
> > +{
> > +     unsigned long vaddr;
> > +
> > +     vaddr = __get_free_page(GFP_KERNEL);
> > +     if (!vaddr || !pgtable_pte_page_ctor(virt_to_page(vaddr)))
> > +             BUG();
> > +     return __pa(vaddr);
> > +}
> > +
> >  static void __init create_pte_mapping(pte_t *ptep,
> >                                     uintptr_t va, phys_addr_t pa,
> >                                     phys_addr_t sz, pgprot_t prot)
> > @@ -279,28 +308,46 @@ pmd_t fixmap_pmd[PTRS_PER_PMD] __page_aligned_bss;
> >  #endif
> >  pmd_t early_pmd[PTRS_PER_PMD * NUM_EARLY_PMDS] __initdata __aligned(PAGE_SIZE);
> >
> > -static pmd_t *__init get_pmd_virt(phys_addr_t pa)
> > +static pmd_t *__init get_pmd_virt_early(phys_addr_t pa)
> >  {
> > -     if (mmu_enabled) {
> > -             clear_fixmap(FIX_PMD);
> > -             return (pmd_t *)set_fixmap_offset(FIX_PMD, pa);
> > -     } else {
> > -             return (pmd_t *)((uintptr_t)pa);
> > -     }
> > +     /* Before MMU is enabled */
> > +     return (pmd_t *)((uintptr_t)pa);
> >  }
> >
> > -static phys_addr_t __init alloc_pmd(uintptr_t va)
> > +static pmd_t *__init get_pmd_virt_fixmap(phys_addr_t pa)
> >  {
> > -     uintptr_t pmd_num;
> > +     clear_fixmap(FIX_PMD);
> > +     return (pmd_t *)set_fixmap_offset(FIX_PMD, pa);
> > +}
> > +
> > +static pmd_t *get_pmd_virt_late(phys_addr_t pa)
> > +{
> > +     return (pmd_t *) __va(pa);
> > +}
> >
> > -     if (mmu_enabled)
> > -             return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
> > +static phys_addr_t __init alloc_pmd_early(uintptr_t va)
> > +{
> > +     uintptr_t pmd_num;
> >
> >       pmd_num = (va - PAGE_OFFSET) >> PGDIR_SHIFT;
> >       BUG_ON(pmd_num >= NUM_EARLY_PMDS);
> >       return (uintptr_t)&early_pmd[pmd_num * PTRS_PER_PMD];
> >  }
> >
> > +static phys_addr_t __init alloc_pmd_fixmap(uintptr_t va)
> > +{
> > +     return memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE);
> > +}
> > +
> > +static phys_addr_t alloc_pmd_late(uintptr_t va)
> > +{
> > +     unsigned long vaddr;
> > +
> > +     vaddr = __get_free_page(GFP_KERNEL);
> > +     BUG_ON(!vaddr);
> > +     return __pa(vaddr);
> > +}
> > +
> >  static void __init create_pmd_mapping(pmd_t *pmdp,
> >                                     uintptr_t va, phys_addr_t pa,
> >                                     phys_addr_t sz, pgprot_t prot)
> > @@ -316,28 +363,28 @@ static void __init create_pmd_mapping(pmd_t *pmdp,
> >       }
> >
> >       if (pmd_none(pmdp[pmd_idx])) {
> > -             pte_phys = alloc_pte(va);
> > +             pte_phys = pt_ops.alloc_pte(va);
> >               pmdp[pmd_idx] = pfn_pmd(PFN_DOWN(pte_phys), PAGE_TABLE);
> > -             ptep = get_pte_virt(pte_phys);
> > +             ptep = pt_ops.get_pte_virt(pte_phys);
> >               memset(ptep, 0, PAGE_SIZE);
> >       } else {
> >               pte_phys = PFN_PHYS(_pmd_pfn(pmdp[pmd_idx]));
> > -             ptep = get_pte_virt(pte_phys);
> > +             ptep = pt_ops.get_pte_virt(pte_phys);
> >       }
> >
> >       create_pte_mapping(ptep, va, pa, sz, prot);
> >  }
> >
> >  #define pgd_next_t           pmd_t
> > -#define alloc_pgd_next(__va) alloc_pmd(__va)
> > -#define get_pgd_next_virt(__pa)      get_pmd_virt(__pa)
> > +#define alloc_pgd_next(__va) pt_ops.alloc_pmd(__va)
> > +#define get_pgd_next_virt(__pa)      pt_ops.get_pmd_virt(__pa)
> >  #define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot)   \
> >       create_pmd_mapping(__nextp, __va, __pa, __sz, __prot)
> >  #define fixmap_pgd_next              fixmap_pmd
> >  #else
> >  #define pgd_next_t           pte_t
> > -#define alloc_pgd_next(__va) alloc_pte(__va)
> > -#define get_pgd_next_virt(__pa)      get_pte_virt(__pa)
> > +#define alloc_pgd_next(__va) pt_ops.alloc_pte(__va)
> > +#define get_pgd_next_virt(__pa)      pt_ops.get_pte_virt(__pa)
> >  #define create_pgd_next_mapping(__nextp, __va, __pa, __sz, __prot)   \
> >       create_pte_mapping(__nextp, __va, __pa, __sz, __prot)
> >  #define fixmap_pgd_next              fixmap_pte
> > @@ -421,6 +468,12 @@ asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> >       BUG_ON((load_pa % map_size) != 0);
> >       BUG_ON(load_sz > MAX_EARLY_MAPPING_SIZE);
> >
> > +     pt_ops.alloc_pte = alloc_pte_early;
> > +     pt_ops.get_pte_virt = get_pte_virt_early;
> > +#ifndef __PAGETABLE_PMD_FOLDED
> > +     pt_ops.alloc_pmd = alloc_pmd_early;
> > +     pt_ops.get_pmd_virt = get_pmd_virt_early;
> > +#endif
> >       /* Setup early PGD for fixmap */
> >       create_pgd_mapping(early_pg_dir, FIXADDR_START,
> >                          (uintptr_t)fixmap_pgd_next, PGDIR_SIZE, PAGE_TABLE);
> > @@ -497,9 +550,16 @@ static void __init setup_vm_final(void)
> >       phys_addr_t pa, start, end;
> >       struct memblock_region *reg;
> >
> > -     /* Set mmu_enabled flag */
> > -     mmu_enabled = true;
> > -
> > +     /**
> > +      * MMU is enabled at this point. But page table setup is not complete yet.
> > +      * fixmap page table alloc functions should be used at this point
> > +      */
> > +     pt_ops.alloc_pte = alloc_pte_fixmap;
> > +     pt_ops.get_pte_virt = get_pte_virt_fixmap;
> > +#ifndef __PAGETABLE_PMD_FOLDED
> > +     pt_ops.alloc_pmd = alloc_pmd_fixmap;
> > +     pt_ops.get_pmd_virt = get_pmd_virt_fixmap;
> > +#endif
> >       /* Setup swapper PGD for fixmap */
> >       create_pgd_mapping(swapper_pg_dir, FIXADDR_START,
> >                          __pa_symbol(fixmap_pgd_next),
> > @@ -533,6 +593,14 @@ static void __init setup_vm_final(void)
> >       /* Move to swapper page table */
> >       csr_write(CSR_SATP, PFN_DOWN(__pa_symbol(swapper_pg_dir)) | SATP_MODE);
> >       local_flush_tlb_all();
> > +
> > +     /* generic page allocation functions must be used to setup page table */
> > +     pt_ops.alloc_pte = alloc_pte_late;
> > +     pt_ops.get_pte_virt = get_pte_virt_late;
> > +#ifndef __PAGETABLE_PMD_FOLDED
> > +     pt_ops.alloc_pmd = alloc_pmd_late;
> > +     pt_ops.get_pmd_virt = get_pmd_virt_late;
> > +#endif
> >  }
> >  #else
> >  asmlinkage void __init setup_vm(uintptr_t dtb_pa)
> > --
> > 2.24.0
> >
>
> --
> Sincerely yours,
> Mike.


-- 
Regards,
Atish