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Message-Id: <20250421142441.395849-3-alexghiti@rivosinc.com>
Date: Mon, 21 Apr 2025 16:24:39 +0200
From: Alexandre Ghiti <alexghiti@...osinc.com>
To: Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Alexandre Ghiti <alex@...ti.fr>,
linux-riscv@...ts.infradead.org,
linux-kernel@...r.kernel.org
Cc: Alexandre Ghiti <alexghiti@...osinc.com>,
Guo Ren <guoren@...nel.org>
Subject: [PATCH v3 2/4] riscv: Add support for Zicbop
Zicbop introduces cache blocks prefetching instructions, add the
necessary support for the kernel to use it in the coming commits.
Co-developed-by: Guo Ren <guoren@...nel.org>
Signed-off-by: Guo Ren <guoren@...nel.org>
Signed-off-by: Alexandre Ghiti <alexghiti@...osinc.com>
---
arch/riscv/Kconfig | 15 +++++++++++++++
arch/riscv/include/asm/barrier.h | 5 -----
arch/riscv/include/asm/cacheflush.h | 1 +
arch/riscv/include/asm/hwcap.h | 1 +
arch/riscv/include/asm/insn-def.h | 6 ++++++
arch/riscv/include/asm/processor.h | 1 -
arch/riscv/kernel/cpufeature.c | 21 +++++++++++++++++++++
arch/riscv/mm/cacheflush.c | 14 +++++++++++---
8 files changed, 55 insertions(+), 9 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index bbec87b79309..28765ce563de 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -842,6 +842,21 @@ config RISCV_ISA_ZICBOZ
If you don't know what to do here, say Y.
+config RISCV_ISA_ZICBOP
+ bool "Zicbop extension support for cache block prefetch"
+ depends on MMU
+ depends on RISCV_ALTERNATIVE
+ default y
+ help
+ Adds support to dynamically detect the presence of the ZICBOP
+ extension (Cache Block Prefetch Operations) and enable its
+ usage.
+
+ The Zicbop extension can be used to prefetch cache blocks for
+ read/write fetch.
+
+ If you don't know what to do here, say Y.
+
config TOOLCHAIN_NEEDS_EXPLICIT_ZICSR_ZIFENCEI
def_bool y
# https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=aed44286efa8ae8717a77d94b51ac3614e2ca6dc
diff --git a/arch/riscv/include/asm/barrier.h b/arch/riscv/include/asm/barrier.h
index e1d9bf1deca6..b8c5726d86ac 100644
--- a/arch/riscv/include/asm/barrier.h
+++ b/arch/riscv/include/asm/barrier.h
@@ -14,11 +14,6 @@
#include <asm/cmpxchg.h>
#include <asm/fence.h>
-#define nop() __asm__ __volatile__ ("nop")
-#define __nops(n) ".rept " #n "\nnop\n.endr\n"
-#define nops(n) __asm__ __volatile__ (__nops(n))
-
-
/* These barriers need to enforce ordering on both devices or memory. */
#define __mb() RISCV_FENCE(iorw, iorw)
#define __rmb() RISCV_FENCE(ir, ir)
diff --git a/arch/riscv/include/asm/cacheflush.h b/arch/riscv/include/asm/cacheflush.h
index 8de73f91bfa3..effa02c2e682 100644
--- a/arch/riscv/include/asm/cacheflush.h
+++ b/arch/riscv/include/asm/cacheflush.h
@@ -80,6 +80,7 @@ void flush_icache_mm(struct mm_struct *mm, bool local);
extern unsigned int riscv_cbom_block_size;
extern unsigned int riscv_cboz_block_size;
+extern unsigned int riscv_cbop_block_size;
void riscv_init_cbo_blocksizes(void);
#ifdef CONFIG_RISCV_DMA_NONCOHERENT
diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
index e3cbf203cdde..affd63e11b0a 100644
--- a/arch/riscv/include/asm/hwcap.h
+++ b/arch/riscv/include/asm/hwcap.h
@@ -105,6 +105,7 @@
#define RISCV_ISA_EXT_ZVFBFWMA 96
#define RISCV_ISA_EXT_ZAAMO 97
#define RISCV_ISA_EXT_ZALRSC 98
+#define RISCV_ISA_EXT_ZICBOP 99
#define RISCV_ISA_EXT_XLINUXENVCFG 127
diff --git a/arch/riscv/include/asm/insn-def.h b/arch/riscv/include/asm/insn-def.h
index 02c92c1657d2..d5adbaec1d01 100644
--- a/arch/riscv/include/asm/insn-def.h
+++ b/arch/riscv/include/asm/insn-def.h
@@ -263,4 +263,10 @@
#define RISCV_INSN_NOP4 _AC(0x00000013, U)
+#ifndef __ASSEMBLY__
+#define nop() __asm__ __volatile__ ("nop")
+#define __nops(n) ".rept " #n "\nnop\n.endr\n"
+#define nops(n) __asm__ __volatile__ (__nops(n))
+#endif
+
#endif /* __ASM_INSN_DEF_H */
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h
index 5f56eb9d114a..09d4c963399a 100644
--- a/arch/riscv/include/asm/processor.h
+++ b/arch/riscv/include/asm/processor.h
@@ -52,7 +52,6 @@
#endif
#ifndef __ASSEMBLY__
-#include <linux/cpumask.h>
struct task_struct;
struct pt_regs;
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 2054f6c4b0ae..743d53415572 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -32,6 +32,7 @@
#define NUM_ALPHA_EXTS ('z' - 'a' + 1)
static bool any_cpu_has_zicboz;
+static bool any_cpu_has_zicbop;
static bool any_cpu_has_zicbom;
unsigned long elf_hwcap __read_mostly;
@@ -119,6 +120,21 @@ static int riscv_ext_zicboz_validate(const struct riscv_isa_ext_data *data,
return 0;
}
+static int riscv_ext_zicbop_validate(const struct riscv_isa_ext_data *data,
+ const unsigned long *isa_bitmap)
+{
+ if (!riscv_cbop_block_size) {
+ pr_err("Zicbop detected in ISA string, disabling as no cbop-block-size found\n");
+ return -EINVAL;
+ }
+ if (!is_power_of_2(riscv_cbop_block_size)) {
+ pr_err("Zicbop disabled as cbop-block-size present, but is not a power-of-2\n");
+ return -EINVAL;
+ }
+ any_cpu_has_zicbop = true;
+ return 0;
+}
+
static int riscv_ext_f_validate(const struct riscv_isa_ext_data *data,
const unsigned long *isa_bitmap)
{
@@ -442,6 +458,7 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = {
__RISCV_ISA_EXT_SUPERSET_VALIDATE(v, RISCV_ISA_EXT_v, riscv_v_exts, riscv_ext_vector_float_validate),
__RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h),
__RISCV_ISA_EXT_SUPERSET_VALIDATE(zicbom, RISCV_ISA_EXT_ZICBOM, riscv_xlinuxenvcfg_exts, riscv_ext_zicbom_validate),
+ __RISCV_ISA_EXT_DATA_VALIDATE(zicbop, RISCV_ISA_EXT_ZICBOP, riscv_ext_zicbop_validate),
__RISCV_ISA_EXT_SUPERSET_VALIDATE(zicboz, RISCV_ISA_EXT_ZICBOZ, riscv_xlinuxenvcfg_exts, riscv_ext_zicboz_validate),
__RISCV_ISA_EXT_DATA(ziccrse, RISCV_ISA_EXT_ZICCRSE),
__RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR),
@@ -1112,6 +1129,10 @@ void __init riscv_user_isa_enable(void)
current->thread.envcfg |= ENVCFG_CBCFE;
else if (any_cpu_has_zicbom)
pr_warn("Zicbom disabled as it is unavailable on some harts\n");
+
+ if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_ZICBOP) &&
+ any_cpu_has_zicbop)
+ pr_warn("Zicbop disabled as it is unavailable on some harts\n");
}
#ifdef CONFIG_RISCV_ALTERNATIVE
diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
index b81672729887..6265052ef8b6 100644
--- a/arch/riscv/mm/cacheflush.c
+++ b/arch/riscv/mm/cacheflush.c
@@ -101,6 +101,9 @@ EXPORT_SYMBOL_GPL(riscv_cbom_block_size);
unsigned int riscv_cboz_block_size;
EXPORT_SYMBOL_GPL(riscv_cboz_block_size);
+unsigned int riscv_cbop_block_size;
+EXPORT_SYMBOL_GPL(riscv_cbop_block_size);
+
static void __init cbo_get_block_size(struct device_node *node,
const char *name, u32 *block_size,
unsigned long *first_hartid)
@@ -125,8 +128,8 @@ static void __init cbo_get_block_size(struct device_node *node,
void __init riscv_init_cbo_blocksizes(void)
{
- unsigned long cbom_hartid, cboz_hartid;
- u32 cbom_block_size = 0, cboz_block_size = 0;
+ unsigned long cbom_hartid, cboz_hartid, cbop_hartid;
+ u32 cbom_block_size = 0, cboz_block_size = 0, cbop_block_size = 0;
struct device_node *node;
struct acpi_table_header *rhct;
acpi_status status;
@@ -138,13 +141,15 @@ void __init riscv_init_cbo_blocksizes(void)
&cbom_block_size, &cbom_hartid);
cbo_get_block_size(node, "riscv,cboz-block-size",
&cboz_block_size, &cboz_hartid);
+ cbo_get_block_size(node, "riscv,cbop-block-size",
+ &cbop_block_size, &cbop_hartid);
}
} else {
status = acpi_get_table(ACPI_SIG_RHCT, 0, &rhct);
if (ACPI_FAILURE(status))
return;
- acpi_get_cbo_block_size(rhct, &cbom_block_size, &cboz_block_size, NULL);
+ acpi_get_cbo_block_size(rhct, &cbom_block_size, &cboz_block_size, &cbop_block_size);
acpi_put_table((struct acpi_table_header *)rhct);
}
@@ -153,6 +158,9 @@ void __init riscv_init_cbo_blocksizes(void)
if (cboz_block_size)
riscv_cboz_block_size = cboz_block_size;
+
+ if (cbop_block_size)
+ riscv_cbop_block_size = cbop_block_size;
}
#ifdef CONFIG_SMP
--
2.39.2
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