[PATCH v7 1/4] RISC-V: Add Svade and Svadu Extensions Support
From: Yong-Xuan Wang
Date: Fri Jul 12 2024 - 04:39:21 EST
Svade and Svadu extensions represent two schemes for managing the PTE A/D
bits. When the PTE A/D bits need to be set, Svade extension intdicates
that a related page fault will be raised. In contrast, the Svadu extension
supports hardware updating of PTE A/D bits. Since the Svade extension is
mandatory and the Svadu extension is optional in RVA23 profile, by default
the M-mode firmware will enable the Svadu extension in the menvcfg CSR
when only Svadu is present in DT.
This patch detects Svade and Svadu extensions from DT and adds
arch_has_hw_pte_young() to enable optimization in MGLRU and
__wp_page_copy_user() when we have the PTE A/D bits hardware updating
support.
Co-developed-by: Jinyu Tang <tjytimi@xxxxxxx>
Signed-off-by: Jinyu Tang <tjytimi@xxxxxxx>
Signed-off-by: Yong-Xuan Wang <yongxuan.wang@xxxxxxxxxx>
Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
---
arch/riscv/Kconfig | 1 +
arch/riscv/include/asm/csr.h | 1 +
arch/riscv/include/asm/hwcap.h | 2 ++
arch/riscv/include/asm/pgtable.h | 13 ++++++++++++-
arch/riscv/kernel/cpufeature.c | 32 ++++++++++++++++++++++++++++++++
5 files changed, 48 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 0525ee2d63c7..3d705e28ff85 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -36,6 +36,7 @@ config RISCV
select ARCH_HAS_PMEM_API
select ARCH_HAS_PREPARE_SYNC_CORE_CMD
select ARCH_HAS_PTE_SPECIAL
+ select ARCH_HAS_HW_PTE_YOUNG
select ARCH_HAS_SET_DIRECT_MAP if MMU
select ARCH_HAS_SET_MEMORY if MMU
select ARCH_HAS_STRICT_KERNEL_RWX if MMU && !XIP_KERNEL
diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
index 25966995da04..524cd4131c71 100644
--- a/arch/riscv/include/asm/csr.h
+++ b/arch/riscv/include/asm/csr.h
@@ -195,6 +195,7 @@
/* 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 e17d0078a651..35d7aa49785d 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -81,6 +81,8 @@
#define RISCV_ISA_EXT_ZTSO 72
#define RISCV_ISA_EXT_ZACAS 73
#define RISCV_ISA_EXT_XANDESPMU 74
+#define RISCV_ISA_EXT_SVADE 75
+#define RISCV_ISA_EXT_SVADU 76
#define RISCV_ISA_EXT_XLINUXENVCFG 127
diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h
index aad8b8ca51f1..ec0cdacd7da0 100644
--- a/arch/riscv/include/asm/pgtable.h
+++ b/arch/riscv/include/asm/pgtable.h
@@ -120,6 +120,7 @@
#include <asm/tlbflush.h>
#include <linux/mm_types.h>
#include <asm/compat.h>
+#include <asm/cpufeature.h>
#define __page_val_to_pfn(_val) (((_val) & _PAGE_PFN_MASK) >> _PAGE_PFN_SHIFT)
@@ -288,7 +289,6 @@ static inline pte_t pud_pte(pud_t pud)
}
#ifdef CONFIG_RISCV_ISA_SVNAPOT
-#include <asm/cpufeature.h>
static __always_inline bool has_svnapot(void)
{
@@ -624,6 +624,17 @@ static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
return __pgprot(prot);
}
+/*
+ * Both Svade and Svadu control the hardware behavior when the PTE A/D bits need to be set. By
+ * default the M-mode firmware enables the hardware updating scheme when only Svadu is present in
+ * DT.
+ */
+#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 5ef48cb20ee1..b2c3fe945e89 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -301,6 +301,8 @@ 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(svade, RISCV_ISA_EXT_SVADE),
+ __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),
@@ -554,6 +556,21 @@ static void __init riscv_fill_hwcap_from_isa_string(unsigned long *isa2hwcap)
clear_bit(RISCV_ISA_EXT_v, isainfo->isa);
}
+ /*
+ * When neither Svade nor Svadu present in DT, it is technically
+ * unknown whether the platform uses Svade or Svadu. Supervisor may
+ * assume Svade to be present and enabled or it can discover based
+ * on mvendorid, marchid, and mimpid. When both Svade and Svadu present
+ * in DT, supervisor must assume Svadu turned-off at boot time. To use
+ * Svadu, supervisor must explicitly enable it using the SBI FWFT extension.
+ */
+ if (!test_bit(RISCV_ISA_EXT_SVADE, isainfo->isa) &&
+ !test_bit(RISCV_ISA_EXT_SVADU, isainfo->isa))
+ set_bit(RISCV_ISA_EXT_SVADE, isainfo->isa);
+ else if (test_bit(RISCV_ISA_EXT_SVADE, isainfo->isa) &&
+ test_bit(RISCV_ISA_EXT_SVADU, isainfo->isa))
+ clear_bit(RISCV_ISA_EXT_SVADU, isainfo->isa);
+
/*
* All "okay" hart should have same isa. Set HWCAP based on
* common capabilities of every "okay" hart, in case they don't
@@ -619,6 +636,21 @@ static int __init riscv_fill_hwcap_from_ext_list(unsigned long *isa2hwcap)
of_node_put(cpu_node);
+ /*
+ * When neither Svade nor Svadu present in DT, it is technically
+ * unknown whether the platform uses Svade or Svadu. Supervisor may
+ * assume Svade to be present and enabled or it can discover based
+ * on mvendorid, marchid, and mimpid. When both Svade and Svadu present
+ * in DT, supervisor must assume Svadu turned-off at boot time. To use
+ * Svadu, supervisor must explicitly enable it using the SBI FWFT extension.
+ */
+ if (!test_bit(RISCV_ISA_EXT_SVADE, isainfo->isa) &&
+ !test_bit(RISCV_ISA_EXT_SVADU, isainfo->isa))
+ set_bit(RISCV_ISA_EXT_SVADE, isainfo->isa);
+ else if (test_bit(RISCV_ISA_EXT_SVADE, isainfo->isa) &&
+ test_bit(RISCV_ISA_EXT_SVADU, isainfo->isa))
+ clear_bit(RISCV_ISA_EXT_SVADU, isainfo->isa);
+
/*
* All "okay" harts should have same isa. Set HWCAP based on
* common capabilities of every "okay" hart, in case they don't.
--
2.17.1