From: Conor Dooley <conor@kernel.org>
To: Andrew Jones <ajones@ventanamicro.com>
Cc: linux-riscv@lists.infradead.org, paul.walmsley@sifive.com,
palmer@dabbelt.com, aou@eecs.berkeley.edu, evan@rivosinc.com,
conor.dooley@microchip.com, apatel@ventanamicro.com
Subject: Re: [PATCH v2 2/6] RISC-V: Enable cbo.zero in usermode
Date: Thu, 31 Aug 2023 17:24:41 +0100 [thread overview]
Message-ID: <20230831-tacking-fiction-1f18a30714d7@spud> (raw)
In-Reply-To: <20230830164954.91987-10-ajones@ventanamicro.com>
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On Wed, Aug 30, 2023 at 06:49:57PM +0200, Andrew Jones wrote:
> When Zicboz is present, enable its instruction (cbo.zero) in
> usermode by setting its respective senvcfg bit. We don't bother
> trying to set this bit per-task, which would also require an
> interface for tasks to request enabling and/or disabling. Instead,
> permanently set the bit for each hart which has the extension when
> bringing it online.
>
> Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
> ---
> arch/riscv/include/asm/cpufeature.h | 2 ++
> arch/riscv/include/asm/csr.h | 1 +
> arch/riscv/include/asm/hwcap.h | 16 ++++++++++++++++
> arch/riscv/kernel/cpufeature.c | 6 ++++++
> arch/riscv/kernel/setup.c | 4 ++++
> arch/riscv/kernel/smpboot.c | 4 ++++
> 6 files changed, 33 insertions(+)
>
> diff --git a/arch/riscv/include/asm/cpufeature.h b/arch/riscv/include/asm/cpufeature.h
> index 23fed53b8815..788fd575c21a 100644
> --- a/arch/riscv/include/asm/cpufeature.h
> +++ b/arch/riscv/include/asm/cpufeature.h
> @@ -30,4 +30,6 @@ DECLARE_PER_CPU(long, misaligned_access_speed);
> /* Per-cpu ISA extensions. */
> extern struct riscv_isainfo hart_isa[NR_CPUS];
>
> +void riscv_user_isa_enable(void);
> +
> #endif
> diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h
> index 7bac43a3176e..e187e76e3df4 100644
> --- a/arch/riscv/include/asm/csr.h
> +++ b/arch/riscv/include/asm/csr.h
> @@ -273,6 +273,7 @@
> #define CSR_SIE 0x104
> #define CSR_STVEC 0x105
> #define CSR_SCOUNTEREN 0x106
> +#define CSR_SENVCFG 0x10a
> #define CSR_SSCRATCH 0x140
> #define CSR_SEPC 0x141
> #define CSR_SCAUSE 0x142
> diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> index f041bfa7f6a0..66178dbd0045 100644
> --- a/arch/riscv/include/asm/hwcap.h
> +++ b/arch/riscv/include/asm/hwcap.h
> @@ -66,6 +66,7 @@
> #ifndef __ASSEMBLY__
>
> #include <linux/jump_label.h>
> +#include <asm/cpufeature.h>
>
> unsigned long riscv_get_elf_hwcap(void);
>
> @@ -130,6 +131,21 @@ riscv_has_extension_unlikely(const unsigned long ext)
> return true;
> }
>
> +static __always_inline bool riscv_cpu_has_extension_likely(int cpu, const unsigned long ext)
> +{
> + if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) && riscv_has_extension_likely(ext))
> + return true;
It'd have been nice to put the explanation for this into the commit
message I think, but w/e. Do it if there's a v3 I guess.
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Thanks,
Conor.
> +
> + return __riscv_isa_extension_available(hart_isa[cpu].isa, ext);
> +}
> +
> +static __always_inline bool riscv_cpu_has_extension_unlikely(int cpu, const unsigned long ext)
> +{
> + if (IS_ENABLED(CONFIG_RISCV_ALTERNATIVE) && riscv_has_extension_unlikely(ext))
> + return true;
> +
> + return __riscv_isa_extension_available(hart_isa[cpu].isa, ext);
> +}
> #endif
>
> #endif /* _ASM_RISCV_HWCAP_H */
> diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> index 31843e9cc80c..a33cf7c89d9e 100644
> --- a/arch/riscv/kernel/cpufeature.c
> +++ b/arch/riscv/kernel/cpufeature.c
> @@ -391,6 +391,12 @@ unsigned long riscv_get_elf_hwcap(void)
> return hwcap;
> }
>
> +void riscv_user_isa_enable(void)
> +{
> + if (riscv_cpu_has_extension_unlikely(smp_processor_id(), RISCV_ISA_EXT_ZICBOZ))
> + csr_set(CSR_SENVCFG, ENVCFG_CBZE);
> +}
> +
> #ifdef CONFIG_RISCV_ALTERNATIVE
> /*
> * Alternative patch sites consider 48 bits when determining when to patch
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 971fe776e2f8..2f053f0763a1 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -25,6 +25,7 @@
> #include <asm/acpi.h>
> #include <asm/alternative.h>
> #include <asm/cacheflush.h>
> +#include <asm/cpufeature.h>
> #include <asm/cpu_ops.h>
> #include <asm/early_ioremap.h>
> #include <asm/pgtable.h>
> @@ -308,9 +309,12 @@ void __init setup_arch(char **cmdline_p)
> riscv_fill_hwcap();
> init_rt_signal_env();
> apply_boot_alternatives();
> +
> if (IS_ENABLED(CONFIG_RISCV_ISA_ZICBOM) &&
> riscv_isa_extension_available(NULL, ZICBOM))
> riscv_noncoherent_supported();
> +
> + riscv_user_isa_enable();
> }
>
> static int __init topology_init(void)
> diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> index f4d6acb38dd0..502b04abda0b 100644
> --- a/arch/riscv/kernel/smpboot.c
> +++ b/arch/riscv/kernel/smpboot.c
> @@ -25,6 +25,8 @@
> #include <linux/of.h>
> #include <linux/sched/task_stack.h>
> #include <linux/sched/mm.h>
> +
> +#include <asm/cpufeature.h>
> #include <asm/cpu_ops.h>
> #include <asm/irq.h>
> #include <asm/mmu_context.h>
> @@ -252,6 +254,8 @@ asmlinkage __visible void smp_callin(void)
> elf_hwcap &= ~COMPAT_HWCAP_ISA_V;
> }
>
> + riscv_user_isa_enable();
> +
> /*
> * Remote TLB flushes are ignored while the CPU is offline, so emit
> * a local TLB flush right now just in case.
> --
> 2.41.0
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv
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next prev parent reply other threads:[~2023-08-31 16:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-30 16:49 [PATCH v2 0/6] RISC-V: Enable cbo.zero in usermode Andrew Jones
2023-08-30 16:49 ` [PATCH v2 1/6] RISC-V: Make zicbom/zicboz errors consistent Andrew Jones
2023-08-30 16:49 ` [PATCH v2 2/6] RISC-V: Enable cbo.zero in usermode Andrew Jones
2023-08-31 16:24 ` Conor Dooley [this message]
2023-08-31 16:39 ` Andrew Jones
2023-08-31 16:46 ` Conor Dooley
2023-08-30 16:49 ` [PATCH v2 3/6] RISC-V: hwprobe: Expose Zicboz extension and its block size Andrew Jones
2023-08-31 16:19 ` Conor Dooley
2023-08-30 16:49 ` [PATCH v2 4/6] RISC-V: selftests: Statically link hwprobe test Andrew Jones
2023-08-30 16:50 ` [PATCH v2 5/6] RISC-V: selftests: Convert hwprobe test to kselftest API Andrew Jones
2023-08-30 16:50 ` [PATCH v2 6/6] RISC-V: selftests: Add CBO tests Andrew Jones
2023-09-01 9:37 ` Wang, Xiao W
2023-09-01 15:12 ` Andrew Jones
2023-08-30 16:52 ` [PATCH v2 0/6] RISC-V: Enable cbo.zero in usermode Andrew Jones
2023-08-30 20:28 ` Palmer Dabbelt
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