linux-kernel - Re: [RFC PATCH 1/3] riscv: errata: cmo: add CMO macro variant with both VA and PA

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Date:   Wed, 4 Jan 2023 16:48:24 +0800
From:   Guo Ren <guoren@...nel.org>
To:     Icenowy Zheng <uwu@...nowy.me>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Heiko Stuebner <heiko@...ech.de>,
        Samuel Holland <samuel@...lland.org>,
        Conor Dooley <conor.dooley@...rochip.com>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 1/3] riscv: errata: cmo: add CMO macro variant with
 both VA and PA

Thx for the patch! It's nice.

Reviewed-by: Guo Ren <guoren@...nel.org>

On Wed, Jan 4, 2023 at 3:42 PM Icenowy Zheng <uwu@...nowy.me> wrote:
>
> The standardized Zicbom extension supports only VA, however there's some
> vendor extensions (e.g. XtheadCmo) that can handle cache management
> operations on PA directly, bypassing the TLB lookup.
>
> Add a CMO alternatives macro variant that come with both VA and PA
> supplied, and the code can be patched to use either the VA or the PA at
> runtime. In this case the codepath is now patched to use VA for Zicbom
> and PA for XtheadCmo.
>
> Signed-off-by: Icenowy Zheng <uwu@...nowy.me>
> ---
>  arch/riscv/include/asm/errata_list.h | 30 ++++++++++++++++++++++++++++
>  1 file changed, 30 insertions(+)
>
> diff --git a/arch/riscv/include/asm/errata_list.h b/arch/riscv/include/asm/errata_list.h
> index 46adc1c9428f..bf80dd58145e 100644
> --- a/arch/riscv/include/asm/errata_list.h
> +++ b/arch/riscv/include/asm/errata_list.h
> @@ -118,6 +118,9 @@ asm volatile(ALTERNATIVE(                                           \
>  #define THEAD_clean_A0 ".long 0x0255000b"
>  #define THEAD_flush_A0 ".long 0x0275000b"
>  #define THEAD_SYNC_S   ".long 0x0190000b"
> +#define THEAD_inval_PA_A0      ".long 0x02a5000b"
> +#define THEAD_clean_PA_A0      ".long 0x0295000b"
> +#define THEAD_flush_PA_A0      ".long 0x02b5000b"
>
>  #define ALT_CMO_OP(_op, _start, _size, _cachesize)                     \
>  asm volatile(ALTERNATIVE_2(                                            \
> @@ -144,6 +147,33 @@ asm volatile(ALTERNATIVE_2(                                                \
>             "r"((unsigned long)(_start) + (_size))                      \
>         : "a0")
>
> +#define ALT_CMO_OP_VPA(_op, _vaddr, _paddr, _size, _cachesize)         \
> +asm volatile(ALTERNATIVE_2(                                            \
> +       __nops(6),                                                      \
> +       "mv a0, %1\n\t"                                                 \
> +       "j 2f\n\t"                                                      \
> +       "3:\n\t"                                                        \
> +       "cbo." __stringify(_op) " (a0)\n\t"                             \
> +       "add a0, a0, %0\n\t"                                            \
> +       "2:\n\t"                                                        \
> +       "bltu a0, %2, 3b\n\t"                                           \
> +       "nop", 0, CPUFEATURE_ZICBOM, CONFIG_RISCV_ISA_ZICBOM,           \
> +       "mv a0, %3\n\t"                                                 \
> +       "j 2f\n\t"                                                      \
> +       "3:\n\t"                                                        \
> +       THEAD_##_op##_PA_A0 "\n\t"                                      \
> +       "add a0, a0, %0\n\t"                                            \
> +       "2:\n\t"                                                        \
> +       "bltu a0, %4, 3b\n\t"                                           \
> +       THEAD_SYNC_S, THEAD_VENDOR_ID,                                  \
> +                       ERRATA_THEAD_CMO, CONFIG_ERRATA_THEAD_CMO)      \
> +       : : "r"(_cachesize),                                            \
> +           "r"((unsigned long)(_vaddr) & ~((_cachesize) - 1UL)),       \
> +           "r"((unsigned long)(_vaddr) + (_size)),                     \
> +           "r"((unsigned long)(_paddr) & ~((_cachesize) - 1UL)),       \
> +           "r"((unsigned long)(_paddr) + (_size))                      \
> +       : "a0")
> +
>  #define THEAD_C9XX_RV_IRQ_PMU                  17
>  #define THEAD_C9XX_CSR_SCOUNTEROF              0x5c5
>
> --
> 2.38.1
>


-- 
Best Regards
 Guo Ren