linux-kernel - [PATCH v3 1/4] RISC-V: Detect and Enable Svadu Extension Support

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Message-Id: <20231102120129.11261-2-yongxuan.wang@sifive.com>
Date:   Thu,  2 Nov 2023 12:01:22 +0000
From:   Yong-Xuan Wang <yongxuan.wang@...ive.com>
To:     linux-riscv@...ts.infradead.org, kvm-riscv@...ts.infradead.org
Cc:     greentime.hu@...ive.com, vincent.chen@...ive.com, tjytimi@....com,
        alex@...ti.fr, conor.dooley@...rochip.com, ajones@...tanamicro.com,
        Yong-Xuan Wang <yongxuan.wang@...ive.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <apatel@...tanamicro.com>,
        Guo Ren <guoren@...nel.org>,
        Daniel Henrique Barboza <dbarboza@...tanamicro.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Jisheng Zhang <jszhang@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Alexandre Ghiti <alexghiti@...osinc.com>,
        Kemeng Shi <shikemeng@...weicloud.com>,
        David Hildenbrand <david@...hat.com>,
        Charlie Jenkins <charlie@...osinc.com>,
        Sergey Matyukevich <sergey.matyukevich@...tacore.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Qinglin Pan <panqinglin2020@...as.ac.cn>,
        Rick Edgecombe <rick.p.edgecombe@...el.com>,
        Evan Green <evan@...osinc.com>,
        Sunil V L <sunilvl@...tanamicro.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v3 1/4] RISC-V: Detect and Enable Svadu Extension Support

Svadu is a RISC-V extension for hardware updating of PTE A/D bits.

In this patch we detect Svadu extension support from DTB and
add arch_has_hw_pte_young() to enable optimization in MGLRU and
__wp_page_copy_user() if Svadu extension is available.

Co-developed-by: Jinyu Tang <tjytimi@....com>
Signed-off-by: Jinyu Tang <tjytimi@....com>
Signed-off-by: Yong-Xuan Wang <yongxuan.wang@...ive.com>
Reviewed-by: Conor Dooley <conor.dooley@...rochip.com>
---
 arch/riscv/include/asm/csr.h     | 1 +
 arch/riscv/include/asm/hwcap.h   | 1 +
 arch/riscv/include/asm/pgtable.h | 6 ++++++
 arch/riscv/kernel/cpufeature.c   | 1 +
 4 files changed, 9 insertions(+)

diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 777cb8299551..e6935fd48c0c 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -194,6 +194,7 @@
 /* xENVCFG flags */
 #define ENVCFG_STCE			(_AC(1, ULL) << 63)
 #define ENVCFG_PBMTE			(_AC(1, ULL) << 62)
+#define ENVCFG_ADUE			(_AC(1, ULL) << 61)
 #define ENVCFG_CBZE			(_AC(1, UL) << 7)
 #define ENVCFG_CBCFE			(_AC(1, UL) << 6)
 #define ENVCFG_CBIE_SHIFT		4
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index b7b58258f6c7..1013661d6516 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -58,6 +58,7 @@
 #define RISCV_ISA_EXT_ZICSR		40
 #define RISCV_ISA_EXT_ZIFENCEI		41
 #define RISCV_ISA_EXT_ZIHPM		42
+#define RISCV_ISA_EXT_SVADU		43
 
 #define RISCV_ISA_EXT_MAX		64
 
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index b2ba3f79cfe9..028b700cd27b 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -629,6 +629,12 @@ static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
 	return __pgprot(prot);
 }
 
+#define arch_has_hw_pte_young arch_has_hw_pte_young
+static inline bool arch_has_hw_pte_young(void)
+{
+	return riscv_has_extension_unlikely(RISCV_ISA_EXT_SVADU);
+}
+
 /*
  * THP functions
  */
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 1cfbba65d11a..ead378c04991 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -178,6 +178,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
 	__RISCV_ISA_EXT_DATA(ssaia, RISCV_ISA_EXT_SSAIA),
 	__RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF),
 	__RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC),
+	__RISCV_ISA_EXT_DATA(svadu, RISCV_ISA_EXT_SVADU),
 	__RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL),
 	__RISCV_ISA_EXT_DATA(svnapot, RISCV_ISA_EXT_SVNAPOT),
 	__RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
-- 
2.17.1