RE: [PATCH v3 08/10] x86/resctrl: Merge AMD/Intel parse_bw() calls

[Babu Moger <babu.moger@amd.com>]

> -----Original Message-----
> From: James Morse <james.morse@arm.com>
> Sent: Monday, May 18, 2020 8:19 AM
> To: x86@kernel.org; linux-kernel@vger.kernel.org
> Cc: Fenghua Yu <fenghua.yu@intel.com>; Reinette Chatre
> <reinette.chatre@intel.com>; Thomas Gleixner <tglx@linutronix.de>; Ingo
> Molnar <mingo@redhat.com>; Borislav Petkov <bp@alien8.de>; H Peter Anvin
> <hpa@zytor.com>; Moger, Babu <Babu.Moger@amd.com>; James Morse
> <james.morse@arm.com>
> Subject: [PATCH v3 08/10] x86/resctrl: Merge AMD/Intel parse_bw() calls
> 
> Now that we've explained arch_needs_linear to resctrl, the parse_bw()
> calls are almost the same between AMD and Intel.
> 
> The difference is '!is_mba_sc()', which is not checked on AMD. This
> will always be true on AMD CPUs as mba_sc cannot be enabled as
> is_mba_linear() is false.
> 
> Removing this duplication means user-space visible behaviour and
> error messages are not validated or generated in different places.
> 
> CC: Babu Moger <Babu.Moger@amd.com>
> Signed-off-by: James Morse <james.morse@arm.com>
> Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>

Reviewed-by : Babu Moger <babu.moger@amd.com>

> ---
>  arch/x86/kernel/cpu/resctrl/core.c        |  3 +-
>  arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 57 +----------------------
>  arch/x86/kernel/cpu/resctrl/internal.h    |  6 +--
>  3 files changed, 5 insertions(+), 61 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c
> b/arch/x86/kernel/cpu/resctrl/core.c
> index c6b73b0ee070..223e5b90bcfd 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -168,6 +168,7 @@ struct rdt_resource rdt_resources_all[] = {
>  		.name			= "MB",
>  		.domains		= domain_init(RDT_RESOURCE_MBA),
>  		.cache_level		= 3,
> +		.parse_ctrlval		= parse_bw,
>  		.format_str		= "%d=%*u",
>  		.fflags			= RFTYPE_RES_MB,
>  	},
> @@ -926,7 +927,6 @@ static __init void rdt_init_res_defs_intel(void)
>  		else if (r->rid == RDT_RESOURCE_MBA) {
>  			r->msr_base = MSR_IA32_MBA_THRTL_BASE;
>  			r->msr_update = mba_wrmsr_intel;
> -			r->parse_ctrlval = parse_bw_intel;
>  		}
>  	}
>  }
> @@ -946,7 +946,6 @@ static __init void rdt_init_res_defs_amd(void)
>  		else if (r->rid == RDT_RESOURCE_MBA) {
>  			r->msr_base = MSR_IA32_MBA_BW_BASE;
>  			r->msr_update = mba_wrmsr_amd;
> -			r->parse_ctrlval = parse_bw_amd;
>  		}
>  	}
>  }
> diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> index e3bcd77add2b..b0e24cb6f85c 100644
> --- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> +++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
> @@ -21,59 +21,6 @@
>  #include <linux/slab.h>
>  #include "internal.h"
> 
> -/*
> - * Check whether MBA bandwidth percentage value is correct. The value is
> - * checked against the minimum and maximum bandwidth values specified by
> - * the hardware. The allocated bandwidth percentage is rounded to the next
> - * control step available on the hardware.
> - */
> -static bool bw_validate_amd(char *buf, unsigned long *data,
> -			    struct rdt_resource *r)
> -{
> -	unsigned long bw;
> -	int ret;
> -
> -	/* temporary: always false on AMD */
> -	if (!r->membw.delay_linear && r->membw.arch_needs_linear) {
> -		rdt_last_cmd_puts("No support for non-linear MB domains\n");
> -		return false;
> -	}
> -
> -	ret = kstrtoul(buf, 10, &bw);
> -	if (ret) {
> -		rdt_last_cmd_printf("Non-decimal digit in MB value %s\n", buf);
> -		return false;
> -	}
> -
> -	if (bw < r->membw.min_bw || bw > r->default_ctrl) {
> -		rdt_last_cmd_printf("MB value %ld out of range [%d,%d]\n",
> bw,
> -				    r->membw.min_bw, r->default_ctrl);
> -		return false;
> -	}
> -
> -	*data = roundup(bw, (unsigned long)r->membw.bw_gran);
> -	return true;
> -}
> -
> -int parse_bw_amd(struct rdt_parse_data *data, struct rdt_resource *r,
> -		 struct rdt_domain *d)
> -{
> -	unsigned long bw_val;
> -
> -	if (d->have_new_ctrl) {
> -		rdt_last_cmd_printf("Duplicate domain %d\n", d->id);
> -		return -EINVAL;
> -	}
> -
> -	if (!bw_validate_amd(data->buf, &bw_val, r))
> -		return -EINVAL;
> -
> -	d->new_ctrl = bw_val;
> -	d->have_new_ctrl = true;
> -
> -	return 0;
> -}
> -
>  /*
>   * Check whether MBA bandwidth percentage value is correct. The value is
>   * checked against the minimum and max bandwidth values specified by the
> @@ -110,8 +57,8 @@ static bool bw_validate(char *buf, unsigned long *data,
> struct rdt_resource *r)
>  	return true;
>  }
> 
> -int parse_bw_intel(struct rdt_parse_data *data, struct rdt_resource *r,
> -		   struct rdt_domain *d)
> +int parse_bw(struct rdt_parse_data *data, struct rdt_resource *r,
> +	     struct rdt_domain *d)
>  {
>  	unsigned long bw_val;
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/internal.h
> b/arch/x86/kernel/cpu/resctrl/internal.h
> index 0b288b6fefd9..5919aae946ba 100644
> --- a/arch/x86/kernel/cpu/resctrl/internal.h
> +++ b/arch/x86/kernel/cpu/resctrl/internal.h
> @@ -470,10 +470,8 @@ struct rdt_resource {
> 
>  int parse_cbm(struct rdt_parse_data *data, struct rdt_resource *r,
>  	      struct rdt_domain *d);
> -int parse_bw_intel(struct rdt_parse_data *data, struct rdt_resource *r,
> -		   struct rdt_domain *d);
> -int parse_bw_amd(struct rdt_parse_data *data, struct rdt_resource *r,
> -		 struct rdt_domain *d);
> +int parse_bw(struct rdt_parse_data *data, struct rdt_resource *r,
> +	     struct rdt_domain *d);
> 
>  extern struct mutex rdtgroup_mutex;
> 
> --
> 2.19.1