Re: [PATCH 2/9] RISC-V: Add Zicboz detection and block size parsing

[Andrew Jones <ajones@ventanamicro.com>]

On Sun, Oct 30, 2022 at 08:47:46PM +0000, Conor Dooley wrote:
> On Thu, Oct 27, 2022 at 03:02:40PM +0200, Andrew Jones wrote:
> > Mostly follow the same pattern as Zicbom, but leave out the toolchain
> > checks as we plan to use the insn-def framework for the cbo.zero
> > instruction.
> 
> nit: I'd prefer to see a commit message that stands on it's own without
> relying on someone knowing how zicbom has been wired up.

Sure, I'll rewrite this for v2.

> 
> > 
> > Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
> > ---
> >  arch/riscv/Kconfig                  | 13 +++++++++++++
> >  arch/riscv/include/asm/cacheflush.h |  3 ++-
> >  arch/riscv/include/asm/hwcap.h      |  1 +
> >  arch/riscv/kernel/cpu.c             |  1 +
> >  arch/riscv/kernel/cpufeature.c      | 10 ++++++++++
> >  arch/riscv/kernel/setup.c           |  2 +-
> >  arch/riscv/mm/cacheflush.c          | 23 +++++++++++++++--------
> >  7 files changed, 43 insertions(+), 10 deletions(-)
> > 
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index 6b48a3ae9843..c20e6fa0c0b1 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -433,6 +433,19 @@ config RISCV_ISA_ZICBOM
> >  
> >  	   If you don't know what to do here, say Y.
> >  
> > +config RISCV_ISA_ZICBOZ
> > +	bool "Zicboz extension support for faster zeroing of memory"
> > +	depends on !XIP_KERNEL && MMU
> > +	select RISCV_ALTERNATIVE
> > +	default y
> > +	help
> > +	   Adds support to dynamically detect the presence of the ZICBOZ
> > +	   extension (cbo.zero instruction) and enable its usage.
> > +
> > +	   The Zicboz extension is used for faster zeroing of memory.
> > +
> > +	   If you don't know what to do here, say Y.
> > +
> >  config FPU
> >  	bool "FPU support"
> >  	default y
> > diff --git a/arch/riscv/include/asm/cacheflush.h b/arch/riscv/include/asm/cacheflush.h
> > index f6fbe7042f1c..5b31568cf5e6 100644
> > --- a/arch/riscv/include/asm/cacheflush.h
> > +++ b/arch/riscv/include/asm/cacheflush.h
> > @@ -43,7 +43,8 @@ void flush_icache_mm(struct mm_struct *mm, bool local);
> >  #endif /* CONFIG_SMP */
> >  
> >  extern unsigned int riscv_cbom_block_size;
> > -void riscv_init_cbom_blocksize(void);
> > +extern unsigned int riscv_cboz_block_size;
> > +void riscv_init_cbo_blocksizes(void);
> >  
> >  #ifdef CONFIG_RISCV_DMA_NONCOHERENT
> >  void riscv_noncoherent_supported(void);
> > diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h
> > index 5d6492bde446..eaa5a972ad2d 100644
> > --- a/arch/riscv/include/asm/hwcap.h
> > +++ b/arch/riscv/include/asm/hwcap.h
> > @@ -45,6 +45,7 @@
> >  #define RISCV_ISA_EXT_ZIHINTPAUSE	29
> >  #define RISCV_ISA_EXT_SSTC		30
> >  #define RISCV_ISA_EXT_SVINVAL		31
> > +#define RISCV_ISA_EXT_ZICBOZ		32
> >  
> >  #define RISCV_ISA_EXT_ID_MAX		RISCV_ISA_EXT_MAX
> >  
> > diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
> > index fa427bdcf773..bf969218f609 100644
> > --- a/arch/riscv/kernel/cpu.c
> > +++ b/arch/riscv/kernel/cpu.c
> > @@ -144,6 +144,7 @@ static struct riscv_isa_ext_data isa_ext_arr[] = {
> >  	__RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT),
> >  	__RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM),
> >  	__RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE),
> > +	__RISCV_ISA_EXT_DATA(zicboz, RISCV_ISA_EXT_ZICBOZ),
> >  	__RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX),
> >  };
> >  
> > diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
> > index 18b9ed4df1f4..e13b3391de76 100644
> > --- a/arch/riscv/kernel/cpufeature.c
> > +++ b/arch/riscv/kernel/cpufeature.c
> > @@ -78,6 +78,15 @@ static bool riscv_isa_extension_check(int id)
> >  			return false;
> >  		}
> >  		return true;
> > +	case RISCV_ISA_EXT_ZICBOZ:
> > +		if (!riscv_cboz_block_size) {
> > +			pr_err("Zicboz detected in ISA string, but no cboz-block-size found\n");
> > +			return false;
> > +		} else if (!is_power_of_2(riscv_cboz_block_size)) {
> > +			pr_err("cboz-block-size present, but is not a power-of-2\n");
> > +			return false;
> > +		}
> > +		return true;
> >  	}
> >  
> >  	return true;
> > @@ -225,6 +234,7 @@ void __init riscv_fill_hwcap(void)
> >  				SET_ISA_EXT_MAP("zihintpause", RISCV_ISA_EXT_ZIHINTPAUSE);
> >  				SET_ISA_EXT_MAP("sstc", RISCV_ISA_EXT_SSTC);
> >  				SET_ISA_EXT_MAP("svinval", RISCV_ISA_EXT_SVINVAL);
> > +				SET_ISA_EXT_MAP("zicboz", RISCV_ISA_EXT_ZICBOZ);
> >  			}
> >  #undef SET_ISA_EXT_MAP
> >  		}
> > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> > index a07917551027..26de0d8fd23d 100644
> > --- a/arch/riscv/kernel/setup.c
> > +++ b/arch/riscv/kernel/setup.c
> > @@ -296,7 +296,7 @@ void __init setup_arch(char **cmdline_p)
> >  	setup_smp();
> >  #endif
> >  
> > -	riscv_init_cbom_blocksize();
> > +	riscv_init_cbo_blocksizes();
> >  	riscv_fill_hwcap();
> >  	apply_boot_alternatives();
> >  #ifdef CONFIG_RISCV_DMA_NONCOHERENT
> > diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c
> > index f096b9966cae..208e0d58bde3 100644
> > --- a/arch/riscv/mm/cacheflush.c
> > +++ b/arch/riscv/mm/cacheflush.c
> > @@ -91,6 +91,9 @@ void flush_icache_pte(pte_t pte)
> >  unsigned int riscv_cbom_block_size;
> >  EXPORT_SYMBOL_GPL(riscv_cbom_block_size);
> >  
> > +unsigned int riscv_cboz_block_size;
> > +EXPORT_SYMBOL_GPL(riscv_cboz_block_size);
> > +
> >  static void cbo_get_block_size(struct device_node *node,
> >  			       const char *name, u32 *blksz,
> >  			       unsigned long *first_hartid)
> > @@ -113,19 +116,23 @@ static void cbo_get_block_size(struct device_node *node,
> >  	}
> >  }
> >  
> > -void riscv_init_cbom_blocksize(void)
> > +void riscv_init_cbo_blocksizes(void)
> >  {
> > +	unsigned long cbom_hartid, cboz_hartid;
> > +	u32 cbom_blksz = 0, cboz_blksz = 0;
> >  	struct device_node *node;
> > -	unsigned long cbom_hartid;
> > -	u32 probed_block_size;
> >  
> > -	probed_block_size = 0;
> >  	for_each_of_cpu_node(node) {
> > -		/* set block-size for cbom extension if available */
> > +		/* set block-size for cbom and/or cboz extension if available */
> >  		cbo_get_block_size(node, "riscv,cbom-block-size",
> > -				   &probed_block_size, &cbom_hartid);
> > +				   &cbom_blksz, &cbom_hartid);
> > +		cbo_get_block_size(node, "riscv,cboz-block-size",
> > +				   &cboz_blksz, &cboz_hartid);
> >  	}
> >  
> > -	if (probed_block_size)
> > -		riscv_cbom_block_size = probed_block_size;
> > +	if (cbom_blksz)
> > +		riscv_cbom_block_size = cbom_blksz;
> 
> As in patch 1, can you stick with s/blksz/block_size/ please.

Will do.

> My poor OCD!!! Other than those minor things:
> Reviewed-by: Conor Dooley <conor.dooley@microchip.com>

Thanks,
drew

> 
> > +
> > +	if (cboz_blksz)
> > +		riscv_cboz_block_size = cboz_blksz;
> >  }
> > -- 
> > 2.37.3
> > 
> > 
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv

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