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

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Message-ID: <20231031220534.37730-1-tony.luck@intel.com>
Date:   Tue, 31 Oct 2023 15:05:34 -0700
From:   Tony Luck <tony.luck@...el.com>
To:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Peter Newman <peternewman@...gle.com>, x86@...nel.org
Cc:     Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-kernel@...r.kernel.org, patches@...ts.linux.dev,
        Tony Luck <tony.luck@...el.com>
Subject: [PATCH] x86/resctrl: Fix unused variable warning in cache_alloc_hsw_probe()

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 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>
---
This has been annoying me for a while as the only warning from the
resctrl code when building with W=1.

N.B. compile tested only. I don't have a Haswell system to check this works.

 arch/x86/kernel/cpu/resctrl/core.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index 19e0681f0435..4084131d391d 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -136,15 +136,16 @@ 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;
+	u32 max_cbm = BIT_MASK(20) - 1;
+	u64 l3_cbm_0;
 
 	if (wrmsr_safe(MSR_IA32_L3_CBM_BASE, max_cbm, 0))
 		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;
-- 
2.41.0