From: Charlie Jenkins <charlie@rivosinc.com>
To: "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,
Charlie Jenkins <charlie@rivosinc.com>
Subject: [PATCH v2 3/8] riscv: Add PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT Kconfig option
Date: Tue, 07 May 2024 18:36:29 -0700 [thread overview]
Message-ID: <20240507-compile_kernel_with_extensions-v2-3-722c21c328c6@rivosinc.com> (raw)
In-Reply-To: <20240507-compile_kernel_with_extensions-v2-0-722c21c328c6@rivosinc.com>
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);
}
static inline unsigned long pte_napot(pte_t pte)
--
2.44.0
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next prev parent reply other threads:[~2024-05-08 1:36 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 ` Charlie Jenkins [this message]
2024-05-08 9:00 ` [PATCH v2 3/8] riscv: Add PLATFORM_SUPPORTS_RISCV_ISA_SVNAPOT " Ben Dooks
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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