linux-kernel - Re: [PATCH v2] x86/resctrl: Fix unused variable warning in cache_alloc_hsw

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Date:   Thu, 2 Nov 2023 08:02:36 -0500
From:   "Moger, Babu" <babu.moger@....com>
To:     Tony Luck <tony.luck@...el.com>
Cc:     "Yu, Fenghua" <fenghua.yu@...el.com>,
        "Chatre, Reinette" <reinette.chatre@...el.com>,
        Peter Newman <peternewman@...gle.com>,
        "x86@...nel.org" <x86@...nel.org>,
        Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "patches@...ts.linux.dev" <patches@...ts.linux.dev>
Subject: Re: [PATCH v2] x86/resctrl: Fix unused variable warning in
 cache_alloc_hsw_probe()

Looks good.

On 11/1/23 16:26, Tony Luck wrote:
> In a "W=1" build gcc throws a warning:
> 
> arch/x86/kernel/cpu/resctrl/core.c: In function ‘cache_alloc_hsw_probe’:
> arch/x86/kernel/cpu/resctrl/core.c:139:16: warning: variable ‘h’ set but not used
> 
> Fix by switching from wrmsr_safe() to wrmsrl_safe(), and from rdmsr()
> to rdmsrl() using a single u64 argument for the MSR value instead of
> the pair of u32 for the high and low halves.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>

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

> ---
> Changes since v1 (suggested by Babu)
> 
> Switch both the wrmsr() and rdmsr() to the 64-bit versions.
> 
>  arch/x86/kernel/cpu/resctrl/core.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
> index 19e0681f0435..d29ebe345de6 100644
> --- a/arch/x86/kernel/cpu/resctrl/core.c
> +++ b/arch/x86/kernel/cpu/resctrl/core.c
> @@ -136,15 +136,15 @@ static inline void cache_alloc_hsw_probe(void)
>  {
>  	struct rdt_hw_resource *hw_res = &rdt_resources_all[RDT_RESOURCE_L3];
>  	struct rdt_resource *r  = &hw_res->r_resctrl;
> -	u32 l, h, max_cbm = BIT_MASK(20) - 1;
> +	u64 max_cbm = BIT_ULL_MASK(20) - 1, l3_cbm_0;
>  
> -	if (wrmsr_safe(MSR_IA32_L3_CBM_BASE, max_cbm, 0))
> +	if (wrmsrl_safe(MSR_IA32_L3_CBM_BASE, max_cbm))
>  		return;
>  
> -	rdmsr(MSR_IA32_L3_CBM_BASE, l, h);
> +	rdmsrl(MSR_IA32_L3_CBM_BASE, l3_cbm_0);
>  
>  	/* If all the bits were set in MSR, return success */
> -	if (l != max_cbm)
> +	if (l3_cbm_0 != max_cbm)
>  		return;
>  
>  	hw_res->num_closid = 4;

-- 
Thanks
Babu Moger