linux-kernel - Re: [PATCH v2 04/10] riscv: Implement sv48 support

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Date:   Mon, 4 Oct 2021 09:31:26 +0200
From:   Alexandre Ghiti <alexandre.ghiti@...onical.com>
To:     Samuel Holland <samuel@...lland.org>
Cc:     Jonathan Corbet <corbet@....net>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Zong Li <zong.li@...ive.com>, Anup Patel <anup@...infault.org>,
        Atish Patra <Atish.Patra@....com>,
        Christoph Hellwig <hch@....de>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Alexander Potapenko <glider@...gle.com>,
        Andrey Konovalov <andreyknvl@...il.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Ard Biesheuvel <ardb@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Kees Cook <keescook@...omium.org>,
        Guo Ren <guoren@...ux.alibaba.com>,
        Heinrich Schuchardt <heinrich.schuchardt@...onical.com>,
        Mayuresh Chitale <mchitale@...tanamicro.com>,
        linux-doc@...r.kernel.org,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org List" <linux-kernel@...r.kernel.org>,
        kasan-dev@...glegroups.com, linux-efi@...r.kernel.org,
        linux-arch@...r.kernel.org
Subject: Re: [PATCH v2 04/10] riscv: Implement sv48 support

On Mon, Oct 4, 2021 at 3:34 AM Samuel Holland <samuel@...lland.org> wrote:
>
> On 9/29/21 9:51 AM, Alexandre Ghiti wrote:
> > By adding a new 4th level of page table, give the possibility to 64bit
> > kernel to address 2^48 bytes of virtual address: in practice, that offers
> > 128TB of virtual address space to userspace and allows up to 64TB of
> > physical memory.
> >
> > If the underlying hardware does not support sv48, we will automatically
> > fallback to a standard 3-level page table by folding the new PUD level into
> > PGDIR level. In order to detect HW capabilities at runtime, we
> > use SATP feature that ignores writes with an unsupported mode.
> >
> > Signed-off-by: Alexandre Ghiti <alexandre.ghiti@...onical.com>
> > ---
> >  arch/riscv/Kconfig                      |   4 +-
> >  arch/riscv/include/asm/csr.h            |   3 +-
> >  arch/riscv/include/asm/fixmap.h         |   1 +
> >  arch/riscv/include/asm/kasan.h          |   2 +-
> >  arch/riscv/include/asm/page.h           |  10 +
> >  arch/riscv/include/asm/pgalloc.h        |  40 ++++
> >  arch/riscv/include/asm/pgtable-64.h     | 108 ++++++++++-
> >  arch/riscv/include/asm/pgtable.h        |  13 +-
> >  arch/riscv/kernel/head.S                |   3 +-
> >  arch/riscv/mm/context.c                 |   4 +-
> >  arch/riscv/mm/init.c                    | 237 ++++++++++++++++++++----
> >  arch/riscv/mm/kasan_init.c              |  91 +++++++--
> >  drivers/firmware/efi/libstub/efi-stub.c |   2 +
> >  13 files changed, 453 insertions(+), 65 deletions(-)
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 13e9c4298fbc..69c5533955ed 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -149,7 +149,7 @@ config PAGE_OFFSET
> >       hex
> >       default 0xC0000000 if 32BIT
> >       default 0x80000000 if 64BIT && !MMU
> > -     default 0xffffffe000000000 if 64BIT
> > +     default 0xffffc00000000000 if 64BIT
> >
> >  config ARCH_FLATMEM_ENABLE
> >       def_bool !NUMA
> > @@ -197,7 +197,7 @@ config FIX_EARLYCON_MEM
> >
> >  config PGTABLE_LEVELS
> >       int
> > -     default 3 if 64BIT
> > +     default 4 if 64BIT
> >       default 2
> >
> >  config LOCKDEP_SUPPORT
> > diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
> > index 87ac65696871..3fdb971c7896 100644
> > --- a/arch/riscv/include/asm/csr.h
> > +++ b/arch/riscv/include/asm/csr.h
> > @@ -40,14 +40,13 @@
> >  #ifndef CONFIG_64BIT
> >  #define SATP_PPN     _AC(0x003FFFFF, UL)
> >  #define SATP_MODE_32 _AC(0x80000000, UL)
> > -#define SATP_MODE    SATP_MODE_32
> >  #define SATP_ASID_BITS       9
> >  #define SATP_ASID_SHIFT      22
> >  #define SATP_ASID_MASK       _AC(0x1FF, UL)
> >  #else
> >  #define SATP_PPN     _AC(0x00000FFFFFFFFFFF, UL)
> >  #define SATP_MODE_39 _AC(0x8000000000000000, UL)
> > -#define SATP_MODE    SATP_MODE_39
> > +#define SATP_MODE_48 _AC(0x9000000000000000, UL)
> >  #define SATP_ASID_BITS       16
> >  #define SATP_ASID_SHIFT      44
> >  #define SATP_ASID_MASK       _AC(0xFFFF, UL)
> > diff --git a/arch/riscv/include/asm/fixmap.h b/arch/riscv/include/asm/fixmap.h
> > index 54cbf07fb4e9..58a718573ad6 100644
> > --- a/arch/riscv/include/asm/fixmap.h
> > +++ b/arch/riscv/include/asm/fixmap.h
> > @@ -24,6 +24,7 @@ enum fixed_addresses {
> >       FIX_HOLE,
> >       FIX_PTE,
> >       FIX_PMD,
> > +     FIX_PUD,
> >       FIX_TEXT_POKE1,
> >       FIX_TEXT_POKE0,
> >       FIX_EARLYCON_MEM_BASE,
> > diff --git a/arch/riscv/include/asm/kasan.h b/arch/riscv/include/asm/kasan.h
> > index a2b3d9cdbc86..1dcf5fa93aa0 100644
> > --- a/arch/riscv/include/asm/kasan.h
> > +++ b/arch/riscv/include/asm/kasan.h
> > @@ -27,7 +27,7 @@
> >   */
> >  #define KASAN_SHADOW_SCALE_SHIFT     3
> >
> > -#define KASAN_SHADOW_SIZE    (UL(1) << ((CONFIG_VA_BITS - 1) - KASAN_SHADOW_SCALE_SHIFT))
> > +#define KASAN_SHADOW_SIZE    (UL(1) << ((VA_BITS - 1) - KASAN_SHADOW_SCALE_SHIFT))
>
> Does this change belong in patch 1, where you remove CONFIG_VA_BITS?

Indeed, I fixed KASAN in this version and wrongly rebased the changes.

Thanks!

Alex

>
> Regards,
> Samuel