linux-kernel - Re: [PATCH v4 2/4] RISC-V: Fix ioremap_cache() and ioremap

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Date:   Wed, 19 Oct 2022 16:19:34 +0200
From:   Heiko Stuebner <heiko@...ech.de>
To:     Palmer Dabbelt <palmer@...belt.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Anup Patel <apatel@...tanamicro.com>
Cc:     Atish Patra <atishp@...shpatra.org>,
        Anup Patel <anup@...infault.org>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Anup Patel <apatel@...tanamicro.com>,
        Mayuresh Chitale <mchitale@...tanamicro.com>
Subject: Re: [PATCH v4 2/4] RISC-V: Fix ioremap_cache() and ioremap_wc() for systems with Svpbmt

Am Mittwoch, 19. Oktober 2022, 15:11:26 CEST schrieb Anup Patel:
> Currently, all flavors of ioremap_xyz() function maps to the generic
> ioremap() which means any ioremap_xyz() call will always map the
> target memory as IO using _PAGE_IOREMAP page attributes. This breaks
> ioremap_cache() and ioremap_wc() on systems with Svpbmt because memory
> remapped using ioremap_cache() and ioremap_wc() will use _PAGE_IOREMAP
> page attributes.
> 
> To address above (just like other architectures), we implement RISC-V
> specific ioremap_cache() and ioremap_wc() which maps memory using page
> attributes as defined by the Svpbmt specification.
> 
> Fixes: ff689fd21cb1 ("riscv: add RISC-V Svpbmt extension support")
> Co-developed-by: Mayuresh Chitale <mchitale@...tanamicro.com>
> Signed-off-by: Mayuresh Chitale <mchitale@...tanamicro.com>
> Signed-off-by: Anup Patel <apatel@...tanamicro.com>

Wasn't there discussion around those functions in general in v2?

In any case, the patch doesn't break anything on qemu and d1, so

Tested-by: Heiko Stuebner <heiko@...ech.de>


> ---
>  arch/riscv/include/asm/io.h      | 10 ++++++++++
>  arch/riscv/include/asm/pgtable.h |  2 ++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/arch/riscv/include/asm/io.h b/arch/riscv/include/asm/io.h
> index 92080a227937..92a31e543388 100644
> --- a/arch/riscv/include/asm/io.h
> +++ b/arch/riscv/include/asm/io.h
> @@ -133,6 +133,16 @@ __io_writes_outs(outs, u64, q, __io_pbr(), __io_paw())
>  #define outsq(addr, buffer, count) __outsq(PCI_IOBASE + (addr), buffer, count)
>  #endif
>  
> +#ifdef CONFIG_MMU
> +#define ioremap_wc(addr, size)		\
> +	ioremap_prot((addr), (size), _PAGE_IOREMAP_WC)
> +#endif
> +
>  #include <asm-generic/io.h>
>  
> +#ifdef CONFIG_MMU
> +#define ioremap_cache(addr, size)	\
> +	ioremap_prot((addr), (size), _PAGE_KERNEL)
> +#endif
> +
>  #endif /* _ASM_RISCV_IO_H */
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 7ec936910a96..346b7c1a3eeb 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -182,6 +182,8 @@ extern struct pt_alloc_ops pt_ops __initdata;
>  #define PAGE_TABLE		__pgprot(_PAGE_TABLE)
>  
>  #define _PAGE_IOREMAP	((_PAGE_KERNEL & ~_PAGE_MTMASK) | _PAGE_IO)
> +#define _PAGE_IOREMAP_WC	((_PAGE_KERNEL & ~_PAGE_MTMASK) | \
> +				 _PAGE_NOCACHE)
>  #define PAGE_KERNEL_IO		__pgprot(_PAGE_IOREMAP)
>  
>  extern pgd_t swapper_pg_dir[];
>