From: Ben Dooks <ben.dooks@codethink.co.uk>
To: "Charlie Jenkins" <charlie@rivosinc.com>,
"Paul Walmsley" <paul.walmsley@sifive.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Albert Ou" <aou@eecs.berkeley.edu>,
"Conor Dooley" <conor.dooley@microchip.com>,
"Song Liu" <song@kernel.org>, "Xi Wang" <xi.wang@gmail.com>,
"Björn Töpel" <bjorn@rivosinc.com>,
"Clément Léger" <cleger@rivosinc.com>,
"Jessica Clarke" <jrtc27@jrtc27.com>,
"Andy Chiu" <andy.chiu@sifive.com>
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 3/8] riscv: Add PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT Kconfig option
Date: Wed, 8 May 2024 10:00:48 +0100 [thread overview]
Message-ID: <b3ff587a-61f5-4abf-b71f-7ad48ff66969@codethink.co.uk> (raw)
In-Reply-To: <20240507-compile_kernel_with_extensions-v2-3-722c21c328c6@rivosinc.com>
On 08/05/2024 02:36, Charlie Jenkins wrote:
> The existing "RISCV_ISA_SVNAPOT" option is repurposed to be used to by
> kernel code to determine if either
> PLATFORM_MAY_SUPPORT_RISCV_ISA_SVNAPOT or
> PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT has been set.
>
> PLATFORM_MAY_SUPPORT_RISCV_ISA_SVNAPOT will check if the hardware
> supports Svnapot before using it, while
> PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT will assume that the hardware
> supports Svnapot.
>
> Signed-off-by: Charlie Jenkins <charlie@rivosinc.com>
> ---
> arch/riscv/Kconfig | 19 -----------------
> arch/riscv/Kconfig.isa | 44 ++++++++++++++++++++++++++++++++++++++++
> arch/riscv/include/asm/pgtable.h | 3 ++-
> 3 files changed, 46 insertions(+), 20 deletions(-)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index c2e9eded0a7d..3c1960e8cd7c 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -484,25 +484,6 @@ config RISCV_ALTERNATIVE_EARLY
> help
> Allows early patching of the kernel for special errata
>
> -config RISCV_ISA_SVNAPOT
> - bool "Svnapot extension support for supervisor mode NAPOT pages"
> - depends on 64BIT && MMU
> - depends on RISCV_ALTERNATIVE
> - default y
> - help
> - Add support for the Svnapot ISA-extension in the kernel when it
> - is detected at boot.
> -
> - The Svnapot extension is used to mark contiguous PTEs as a range
> - of contiguous virtual-to-physical translations for a naturally
> - aligned power-of-2 (NAPOT) granularity larger than the base 4KB page
> - size. When HUGETLBFS is also selected this option unconditionally
> - allocates some memory for each NAPOT page size supported by the kernel.
> - When optimizing for low memory consumption and for platforms without
> - the Svnapot extension, it may be better to say N here.
> -
> - If you don't know what to do here, say Y.
> -
> config RISCV_ISA_SVPBMT
> bool "Svpbmt extension support for supervisor mode page-based memory types"
> depends on 64BIT && MMU
> diff --git a/arch/riscv/Kconfig.isa b/arch/riscv/Kconfig.isa
> index 0663c98b5b17..37585bcd763e 100644
> --- a/arch/riscv/Kconfig.isa
> +++ b/arch/riscv/Kconfig.isa
> @@ -124,3 +124,47 @@ config RISCV_ISA_V_PREEMPTIVE
> This config allows kernel to run SIMD without explicitly disable
> preemption. Enabling this config will result in higher memory
> consumption due to the allocation of per-task's kernel Vector context.
> +
> +config RISCV_ISA_SVNAPOT
> + bool
> +
> +choice
> + prompt "Svnapot extension support for supervisor mode NAPOT pages"
> + default PLATFORM_MAY_SUPPORT_RISCV_ISA_SVNAPOT
> + help
> + This selects the level of support for Svnapot in the Linux Kernel.
> +
> + The Svnapot extension is used to mark contiguous PTEs as a range
> + of contiguous virtual-to-physical translations for a naturally
> + aligned power-of-2 (NAPOT) granularity larger than the base 4KB page
> + size. When HUGETLBFS is also selected this option unconditionally
> + allocates some memory for each NAPOT page size supported by the kernel.
> + When optimizing for low memory consumption and for platforms without
> + the Svnapot extension, it may be better to prohibit Svnapot.
> +
> +config PROHIBIT_RISCV_ISA_SVNAPOT
> + bool "Prohibit Svnapot extension"
> + help
> + Regardless of if the platform supports Svnapot, prohibit the kernel
> + from using Svnapot.
> +
> +config PLATFORM_MAY_SUPPORT_RISCV_ISA_SVNAPOT
> + bool "Allow Svnapot extension if supported"
> + depends on 64BIT && MMU
> + depends on RISCV_ALTERNATIVE
> + select RISCV_ISA_SVNAPOT
> + help
> + Add support for the Svnapot ISA-extension in the kernel when it
> + is detected at boot.
> +
> +config PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT
> + bool "Emit Svnapot mappings when building Linux"
> + depends on 64BIT && MMU
> + depends on NONPORTABLE
> + select RISCV_ISA_SVNAPOT
> + help
> + Compile a kernel that assumes that the platform supports Svnapot.
> + This option produces a kernel that will not run on systems that do
> + not support Svnapot.
> +
> +endchoice
> diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
> index 6afd6bb4882e..432be9691b78 100644
> --- a/arch/riscv/include/asm/pgtable.h
> +++ b/arch/riscv/include/asm/pgtable.h
> @@ -289,7 +289,8 @@ static inline pte_t pud_pte(pud_t pud)
>
> static __always_inline bool has_svnapot(void)
> {
> - return riscv_has_extension_likely(RISCV_ISA_EXT_SVNAPOT);
> + return IS_ENABLED(CONFIG_PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT) ||
> + riscv_has_extension_likely(RISCV_ISA_EXT_SVNAPOT);
could you add the IS_ENABLED(*) check into riscv_has_extension_likely
and other such functions?
--
Ben Dooks http://www.codethink.co.uk/
Senior Engineer Codethink - Providing Genius
https://www.codethink.co.uk/privacy.html
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next prev parent reply other threads:[~2024-05-08 9:01 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-08 1:36 [PATCH v2 0/8] riscv: Support compiling the kernel with more extensions Charlie Jenkins
2024-05-08 1:36 ` [PATCH v2 1/8] riscv: Add PLATFORM_MAY_SUPPORT_RISCV_ISA_C Kconfig option Charlie Jenkins
2024-05-08 1:36 ` [PATCH v2 2/8] riscv: Add PLATFORM_MAY_SUPPORT_RISCV_ISA_V " Charlie Jenkins
2024-05-10 20:43 ` Conor Dooley
2024-05-10 21:43 ` Charlie Jenkins
2024-05-10 22:26 ` Conor Dooley
2024-05-15 14:34 ` Conor Dooley
2024-05-08 1:36 ` [PATCH v2 3/8] riscv: Add PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT " Charlie Jenkins
2024-05-08 9:00 ` Ben Dooks [this message]
2024-05-08 17:05 ` Charlie Jenkins
2024-05-08 1:36 ` [PATCH v2 4/8] riscv: Move RISCV_ISA_SVPBMT to Kconfig.isa Charlie Jenkins
2024-05-08 1:36 ` [PATCH v2 5/8] riscv: Add PLATFORM_SUPPORTS_RISCV_ISA_ZBB Kconfig option Charlie Jenkins
2024-05-08 1:36 ` [PATCH v2 6/8] riscv: Add PLATFORM_SUPPORTS_RISCV_ISA_ZBA " Charlie Jenkins
2024-05-08 1:36 ` [PATCH v2 7/8] riscv: Add PLATFORM_SUPPORTS_RISCV_ISA_ZBC " Charlie Jenkins
2024-05-08 1:36 ` [PATCH v2 8/8] riscv: Add PLATFORM_SUPPORTS_RISCV_ISA_ZBS " Charlie Jenkins
2024-05-09 20:25 ` [PATCH v2 0/8] riscv: Support compiling the kernel with more extensions Conor Dooley
2024-05-09 21:16 ` Charlie Jenkins
2024-05-09 22:08 ` Conor Dooley
2024-05-09 22:55 ` Charlie Jenkins
2024-05-10 8:25 ` Conor Dooley
2024-05-10 8:35 ` Conor Dooley
2024-05-10 16:48 ` Charlie Jenkins
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