linux-kernel - [PATCH 5.19 099/101] x86/cacheinfo: Add a cpu_llc_shared

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Date:   Mon,  3 Oct 2022 09:11:35 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Saurabh Sengar <ssengar@...ux.microsoft.com>,
        Borislav Petkov <bp@...e.de>
Subject: [PATCH 5.19 099/101] x86/cacheinfo: Add a cpu_llc_shared_mask() UP variant

From: Borislav Petkov <bp@...e.de>

commit df5b035b5683d6a25f077af889fb88e09827f8bc upstream.

On a CONFIG_SMP=n kernel, the LLC shared mask is 0, which prevents
__cache_amd_cpumap_setup() from doing the L3 masks setup, and more
specifically from setting up the shared_cpu_map and shared_cpu_list
files in sysfs, leading to lscpu from util-linux getting confused and
segfaulting.

Add a cpu_llc_shared_mask() UP variant which returns a mask with a
single bit set, i.e., for CPU0.

Fixes: 2b83809a5e6d ("x86/cpu/amd: Derive L3 shared_cpu_map from cpu_llc_shared_mask")
Reported-by: Saurabh Sengar <ssengar@...ux.microsoft.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Cc: <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/1660148115-302-1-git-send-email-ssengar@linux.microsoft.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/include/asm/smp.h |   25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -21,16 +21,6 @@ DECLARE_PER_CPU_READ_MOSTLY(u16, cpu_llc
 DECLARE_PER_CPU_READ_MOSTLY(u16, cpu_l2c_id);
 DECLARE_PER_CPU_READ_MOSTLY(int, cpu_number);
 
-static inline struct cpumask *cpu_llc_shared_mask(int cpu)
-{
-	return per_cpu(cpu_llc_shared_map, cpu);
-}
-
-static inline struct cpumask *cpu_l2c_shared_mask(int cpu)
-{
-	return per_cpu(cpu_l2c_shared_map, cpu);
-}
-
 DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_cpu_to_apicid);
 DECLARE_EARLY_PER_CPU_READ_MOSTLY(u32, x86_cpu_to_acpiid);
 DECLARE_EARLY_PER_CPU_READ_MOSTLY(u16, x86_bios_cpu_apicid);
@@ -172,6 +162,16 @@ extern int safe_smp_processor_id(void);
 # define safe_smp_processor_id()	smp_processor_id()
 #endif
 
+static inline struct cpumask *cpu_llc_shared_mask(int cpu)
+{
+	return per_cpu(cpu_llc_shared_map, cpu);
+}
+
+static inline struct cpumask *cpu_l2c_shared_mask(int cpu)
+{
+	return per_cpu(cpu_l2c_shared_map, cpu);
+}
+
 #else /* !CONFIG_SMP */
 #define wbinvd_on_cpu(cpu)     wbinvd()
 static inline int wbinvd_on_all_cpus(void)
@@ -179,6 +179,11 @@ static inline int wbinvd_on_all_cpus(voi
 	wbinvd();
 	return 0;
 }
+
+static inline struct cpumask *cpu_llc_shared_mask(int cpu)
+{
+	return (struct cpumask *)cpumask_of(0);
+}
 #endif /* CONFIG_SMP */
 
 extern unsigned disabled_cpus;