Re: [PATCH V4 2/2] riscv: add RISC-V Svpbmt extension supports

[Wei Fu <wefu@redhat.com>]

Hi Heiko,
thanks , yup, my typo, fixed in my new version .

On Wed, Dec 1, 2021 at 2:46 AM Heiko Stübner <heiko@sntech.de> wrote:
>
> Am Montag, 29. November 2021, 02:40:07 CET schrieb wefu@redhat.com:
> > From: Wei Fu <wefu@redhat.com>
> >
> > This patch follows the standard pure RISC-V Svpbmt extension in
> > privilege spec to solve the non-coherent SOC dma synchronization
> > issues.
> >
> > Here is the svpbmt PTE format:
> > | 63 | 62-61 | 60-8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
> >   N     MT     RSW    D   A   G   U   X   W   R   V
> >         ^
> >
> > Of the Reserved bits [63:54] in a leaf PTE, the high bit is already
> > allocated (as the N bit), so bits [62:61] are used as the MT (aka
> > MemType) field. This field specifies one of three memory types that
> > are close equivalents (or equivalent in effect) to the three main x86
> > and ARMv8 memory types - as shown in the following table.
> >
> > RISC-V
> > Encoding &
> > MemType     RISC-V Description
> > ----------  ------------------------------------------------
> > 00 - PMA    Normal Cacheable, No change to implied PMA memory type
> > 01 - NC     Non-cacheable, idempotent, weakly-ordered Main Memory
> > 10 - IO     Non-cacheable, non-idempotent, strongly-ordered I/O memory
> > 11 - Rsvd   Reserved for future standard use
> >
> > The standard protection_map[] needn't be modified because the "PMA"
> > type keeps the highest bits zero. And the whole modification is
> > limited in the arch/riscv/* and using a global variable
> > (__svpbmt) as _PAGE_MASK/IO/NOCACHE for pgprot_noncached
> > (&writecombine) in pgtable.h. We also add _PAGE_CHG_MASK to filter
> > PFN than before.
> >
> > Enable it in devicetree - (Add "riscv,svpbmt" in the mmu of cpu node)
> >  - mmu:
> >      riscv,svpmbt
> >
> > Signed-off-by: Wei Fu <wefu@redhat.com>
> > Co-developed-by: Liu Shaohua <liush@allwinnertech.com>
> > Signed-off-by: Liu Shaohua <liush@allwinnertech.com>
> > Co-developed-by: Guo Ren <guoren@kernel.org>
> > Signed-off-by: Guo Ren <guoren@kernel.org>
> > Cc: Palmer Dabbelt <palmerdabbelt@google.com>
> > Cc: Christoph Hellwig <hch@lst.de>
> > Cc: Anup Patel <anup.patel@wdc.com>
> > Cc: Arnd Bergmann <arnd@arndb.de>
> > Cc: Atish Patra <atish.patra@wdc.com>
> > Cc: Drew Fustini <drew@beagleboard.org>
> > Cc: Wei Fu <wefu@redhat.com>
> > Cc: Wei Wu <lazyparser@gmail.com>
> > Cc: Chen-Yu Tsai <wens@csie.org>
> > Cc: Maxime Ripard <maxime@cerno.tech>
> > Cc: Daniel Lustig <dlustig@nvidia.com>
> > Cc: Greg Favor <gfavor@ventanamicro.com>
> > Cc: Andrea Mondelli <andrea.mondelli@huawei.com>
> > Cc: Jonathan Behrens <behrensj@mit.edu>
> > Cc: Xinhaoqu (Freddie) <xinhaoqu@huawei.com>
> > Cc: Bill Huffman <huffman@cadence.com>
> > Cc: Nick Kossifidis <mick@ics.forth.gr>
> > Cc: Allen Baum <allen.baum@esperantotech.com>
> > Cc: Josh Scheid <jscheid@ventanamicro.com>
> > Cc: Richard Trauben <rtrauben@gmail.com>
> > ---
> >  arch/riscv/include/asm/fixmap.h       |  2 +-
> >  arch/riscv/include/asm/pgtable-64.h   | 21 ++++++++++++---
> >  arch/riscv/include/asm/pgtable-bits.h | 39 +++++++++++++++++++++++++--
> >  arch/riscv/include/asm/pgtable.h      | 39 ++++++++++++++++++++-------
> >  arch/riscv/kernel/cpufeature.c        | 35 ++++++++++++++++++++++++
> >  arch/riscv/mm/init.c                  |  5 ++++
> >  6 files changed, 126 insertions(+), 15 deletions(-)
> >
> > diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
> > index 54cbf07fb4e9..5acd99d08e74 100644
> > --- a/arch/riscv/include/asm/fixmap.h
> > +++ b/arch/riscv/include/asm/fixmap.h
> > @@ -43,7 +43,7 @@ enum fixed_addresses {
> >       __end_of_fixed_addresses
> >  };
> >
> > -#define FIXMAP_PAGE_IO               PAGE_KERNEL
> > +#define FIXMAP_PAGE_IO               PAGE_IOREMAP
> >
> >  #define __early_set_fixmap   __set_fixmap
> >
> > diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h
> > index 228261aa9628..16d251282b1d 100644
> > --- a/arch/riscv/include/asm/pgtable-64.h
> > +++ b/arch/riscv/include/asm/pgtable-64.h
> > @@ -59,14 +59,29 @@ static inline void pud_clear(pud_t *pudp)
> >       set_pud(pudp, __pud(0));
> >  }
> >
> > +static inline unsigned long _chg_of_pmd(pmd_t pmd)
> > +{
> > +     return (pmd_val(pmd) & _PAGE_CHG_MASK);
> > +}
> > +
> > +static inline unsigned long _chg_of_pud(pud_t pud)
> > +{
> > +     return (pud_val(pud) & _PAGE_CHG_MASK);
> > +}
> > +
> > +static inline unsigned long _chg_of_pte(pte_t pte)
> > +{
> > +     return (pte_val(pte) & _PAGE_CHG_MASK);
> > +}
> > +
> >  static inline pmd_t *pud_pgtable(pud_t pud)
> >  {
> > -     return (pmd_t *)pfn_to_virt(pud_val(pud) >> _PAGE_PFN_SHIFT);
> > +     return (pmd_t *)pfn_to_virt(_chg_of_pud(pud) >> _PAGE_PFN_SHIFT);
> >  }
> >
> >  static inline struct page *pud_page(pud_t pud)
> >  {
> > -     return pfn_to_page(pud_val(pud) >> _PAGE_PFN_SHIFT);
> > +     return pfn_to_page(_chg_of_pud(pud) >> _PAGE_PFN_SHIFT);
> >  }
> >
> >  static inline pmd_t pfn_pmd(unsigned long pfn, pgprot_t prot)
> > @@ -76,7 +91,7 @@ static inline pmd_t pfn_pmd(unsigned long pfn, pgprot_t prot)
> >
> >  static inline unsigned long _pmd_pfn(pmd_t pmd)
> >  {
> > -     return pmd_val(pmd) >> _PAGE_PFN_SHIFT;
> > +     return _chg_of_pmd(pmd) >> _PAGE_PFN_SHIFT;
> >  }
> >
> >  #define mk_pmd(page, prot)    pfn_pmd(page_to_pfn(page), prot)
> > diff --git a/arch/riscv/include/asm/pgtable-bits.h b/arch/riscv/include/asm/pgtable-bits.h
> > index 2ee413912926..e5b0fce4ddc5 100644
> > --- a/arch/riscv/include/asm/pgtable-bits.h
> > +++ b/arch/riscv/include/asm/pgtable-bits.h
> > @@ -7,7 +7,7 @@
> >  #define _ASM_RISCV_PGTABLE_BITS_H
> >
> >  /*
> > - * PTE format:
> > + * rv32 PTE format:
> >   * | XLEN-1  10 | 9             8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
> >   *       PFN      reserved for SW   D   A   G   U   X   W   R   V
> >   */
> > @@ -24,6 +24,40 @@
> >  #define _PAGE_DIRTY     (1 << 7)    /* Set by hardware on any write */
> >  #define _PAGE_SOFT      (1 << 8)    /* Reserved for software */
> >
> > +#if !defined(__ASSEMBLY__) && defined(CONFIG_64BIT)
> > +/*
> > + * rv64 PTE format:
> > + * | 63 | 62 61 | 60 54 | 53  10 | 9             8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0
> > + *   N      MT     RSV    PFN      reserved for SW   D   A   G   U   X   W   R   V
> > + * [62:61] Memory Type definitions:
> > + *  00 - PMA    Normal Cacheable, No change to implied PMA memory type
> > + *  01 - NC     Non-cacheable, idempotent, weakly-ordered Main Memory
> > + *  10 - IO     Non-cacheable, non-idempotent, strongly-ordered I/O memory
> > + *  11 - Rsvd   Reserved for future standard use
> > + */
> > +#define _SVPBMT_PMA          0UL
> > +#define _SVPBMT_NC           (1UL << 61)
> > +#define _SVPBMT_IO           (1UL << 62)
> > +#define _SVPBMT_MASK         (_SVPBMT_NC | _SVPBMT_IO)
> > +
> > +extern struct __svpbmt_struct {
> > +     unsigned long mask;
> > +     unsigned long pma;
> > +     unsigned long nocache;
> > +     unsigned long io;
> > +} __svpbmt __cacheline_aligned;
> > +
> > +#define _PAGE_MASK           __svpbmt.mask
> > +#define _PAGE_PMA            __svpbmt.pma
> > +#define _PAGE_NOCACHE                __svpbmt.nocache
> > +#define _PAGE_IO             __svpbmt.io
> > +#else
> > +#define _PAGE_MASK           0
> > +#define _PAGE_PMA            0
> > +#define _PAGE_NOCACHE                0
> > +#define _PAGE_IO             0
> > +#endif /* !__ASSEMBLY__ && CONFIG_64BIT */
> > +
> >  #define _PAGE_SPECIAL   _PAGE_SOFT
> >  #define _PAGE_TABLE     _PAGE_PRESENT
> >
> > @@ -38,7 +72,8 @@
> >  /* Set of bits to preserve across pte_modify() */
> >  #define _PAGE_CHG_MASK  (~(unsigned long)(_PAGE_PRESENT | _PAGE_READ |       \
> >                                         _PAGE_WRITE | _PAGE_EXEC |    \
> > -                                       _PAGE_USER | _PAGE_GLOBAL))
> > +                                       _PAGE_USER | _PAGE_GLOBAL |   \
> > +                                       _PAGE_MASK))
> >  /*
> >   * when all of R/W/X are zero, the PTE is a pointer to the next level
> >   * of the page table; otherwise, it is a leaf PTE.
> > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> > index bf204e7c1f74..0f7a6541015f 100644
> > --- a/arch/riscv/include/asm/pgtable.h
> > +++ b/arch/riscv/include/asm/pgtable.h
> > @@ -138,7 +138,8 @@
> >                               | _PAGE_PRESENT \
> >                               | _PAGE_ACCESSED \
> >                               | _PAGE_DIRTY \
> > -                             | _PAGE_GLOBAL)
> > +                             | _PAGE_GLOBAL \
> > +                             | _PAGE_PMA)
> >
> >  #define PAGE_KERNEL          __pgprot(_PAGE_KERNEL)
> >  #define PAGE_KERNEL_READ     __pgprot(_PAGE_KERNEL & ~_PAGE_WRITE)
> > @@ -148,11 +149,9 @@
> >
> >  #define PAGE_TABLE           __pgprot(_PAGE_TABLE)
> >
> > -/*
> > - * The RISC-V ISA doesn't yet specify how to query or modify PMAs, so we can't
> > - * change the properties of memory regions.
> > - */
> > -#define _PAGE_IOREMAP _PAGE_KERNEL
> > +#define _PAGE_IOREMAP        ((_PAGE_KERNEL & ~_PAGE_MASK) | _PAGE_IO)
> > +
> > +#define PAGE_IOREMAP         __pgprot(_PAGE_IOREMAP)
> >
> >  extern pgd_t swapper_pg_dir[];
> >
> > @@ -232,12 +231,12 @@ static inline unsigned long _pgd_pfn(pgd_t pgd)
> >
> >  static inline struct page *pmd_page(pmd_t pmd)
> >  {
> > -     return pfn_to_page(pmd_val(pmd) >> _PAGE_PFN_SHIFT);
> > +     return pfn_to_page(_chg_of_pmd(pmd) >> _PAGE_PFN_SHIFT);
> >  }
> >
> >  static inline unsigned long pmd_page_vaddr(pmd_t pmd)
> >  {
> > -     return (unsigned long)pfn_to_virt(pmd_val(pmd) >> _PAGE_PFN_SHIFT);
> > +     return (unsigned long)pfn_to_virt(_chg_of_pmd(pmd) >> _PAGE_PFN_SHIFT);
> >  }
> >
> >  static inline pte_t pmd_pte(pmd_t pmd)
> > @@ -253,7 +252,7 @@ static inline pte_t pud_pte(pud_t pud)
> >  /* Yields the page frame number (PFN) of a page table entry */
> >  static inline unsigned long pte_pfn(pte_t pte)
> >  {
> > -     return (pte_val(pte) >> _PAGE_PFN_SHIFT);
> > +     return (_chg_of_pte(pte) >> _PAGE_PFN_SHIFT);
> >  }
> >
> >  #define pte_page(x)     pfn_to_page(pte_pfn(x))
> > @@ -492,6 +491,28 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma,
> >       return ptep_test_and_clear_young(vma, address, ptep);
> >  }
> >
> > +#define pgprot_noncached pgprot_noncached
> > +static inline pgprot_t pgprot_noncached(pgprot_t _prot)
> > +{
> > +     unsigned long prot = pgprot_val(_prot);
> > +
> > +     prot &= ~_PAGE_MASK;
> > +     prot |= _PAGE_IO;
> > +
> > +     return __pgprot(prot);
> > +}
> > +
> > +#define pgprot_writecombine pgprot_writecombine
> > +static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
> > +{
> > +     unsigned long prot = pgprot_val(_prot);
> > +
> > +     prot &= ~_PAGE_MASK;
> > +     prot |= _PAGE_NOCACHE;
> > +
> > +     return __pgprot(prot);
> > +}
> > +
> >  /*
> >   * THP functions
> >   */
> > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> > index d959d207a40d..fa7480cb8b87 100644
> > --- a/arch/riscv/kernel/cpufeature.c
> > +++ b/arch/riscv/kernel/cpufeature.c
> > @@ -8,6 +8,7 @@
> >
> >  #include <linux/bitmap.h>
> >  #include <linux/of.h>
> > +#include <linux/pgtable.h>
> >  #include <asm/processor.h>
> >  #include <asm/hwcap.h>
> >  #include <asm/smp.h>
> > @@ -59,6 +60,38 @@ bool __riscv_isa_extension_available(const unsigned long *isa_bitmap, int bit)
> >  }
> >  EXPORT_SYMBOL_GPL(__riscv_isa_extension_available);
> >
> > +static void __init mmu_supports_svpbmt(void)
> > +{
> > +#if defined(CONFIG_MMU) && defined(CONFIG_64BIT)
> > +     struct device_node *node;
> > +     const char *str;
> > +
> > +     for_each_of_cpu_node(node) {
> > +             if (of_property_read_string(node, "mmu-type", &str))
> > +                     continue;
> > +
> > +             if (!strncmp(str + 6, "none", 4))
> > +                     continue;
> > +
> > +             if (of_property_read_string(node, "mmu", &str))
> > +                     continue;
> > +
> > +             if (strncmp(str + 6, "svpmbt", 6))
>
> same here ... check for "svpbmt" [m seems to be at the wrong position]
>
>
> > +                     continue;
> > +     }
> > +
> > +     __svpbmt.pma            = _SVPBMT_PMA;
> > +     __svpbmt.nocache        = _SVPBMT_NC;
> > +     __svpbmt.io             = _SVPBMT_IO;
> > +     __svpbmt.mask           = _SVPBMT_MASK;
> > +#endif
> > +}
> > +
> > +static void __init mmu_supports(void)
> > +{
> > +     mmu_supports_svpbmt();
> > +}
> > +
> >  void __init riscv_fill_hwcap(void)
> >  {
> >       struct device_node *node;
> > @@ -67,6 +100,8 @@ void __init riscv_fill_hwcap(void)
> >       size_t i, j, isa_len;
> >       static unsigned long isa2hwcap[256] = {0};
> >
> > +     mmu_supports();
> > +
> >       isa2hwcap['i'] = isa2hwcap['I'] = COMPAT_HWCAP_ISA_I;
> >       isa2hwcap['m'] = isa2hwcap['M'] = COMPAT_HWCAP_ISA_M;
> >       isa2hwcap['a'] = isa2hwcap['A'] = COMPAT_HWCAP_ISA_A;
> > diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> > index 24b2b8044602..e4e658165ee1 100644
> > --- a/arch/riscv/mm/init.c
> > +++ b/arch/riscv/mm/init.c
> > @@ -854,3 +854,8 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
> >       return vmemmap_populate_basepages(start, end, node, NULL);
> >  }
> >  #endif
> > +
> > +#if defined(CONFIG_64BIT)
> > +struct __svpbmt_struct __svpbmt __ro_after_init;
> > +EXPORT_SYMBOL(__svpbmt);
> > +#endif
> >
>
>
>
>