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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Sudeep Holla <sudeep.holla@arm.com>,
        Wang Qing <wangqing@vivo.com>
Subject: [PATCH 5.15 033/177] arch_topology: Do not set llc_sibling if llc_id is invalid
Date:   Wed,  4 May 2022 18:43:46 +0200
Message-Id: <20220504153055.948533399@linuxfoundation.org>
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From: Wang Qing <wangqing@vivo.com>

commit 1dc9f1a66e1718479e1c4f95514e1750602a3cb9 upstream.

When ACPI is not enabled, cpuid_topo->llc_id = cpu_topo->llc_id = -1, which
will set llc_sibling 0xff(...), this is misleading.

Don't set llc_sibling(default 0) if we don't know the cache topology.

Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Wang Qing <wangqing@vivo.com>
Fixes: 37c3ec2d810f ("arm64: topology: divorce MC scheduling domain from core_siblings")
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/1649644580-54626-1-git-send-email-wangqing@vivo.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/base/arch_topology.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/base/arch_topology.c
+++ b/drivers/base/arch_topology.c
@@ -609,7 +609,7 @@ void update_siblings_masks(unsigned int
 	for_each_online_cpu(cpu) {
 		cpu_topo = &cpu_topology[cpu];
 
-		if (cpuid_topo->llc_id == cpu_topo->llc_id) {
+		if (cpu_topo->llc_id != -1 && cpuid_topo->llc_id == cpu_topo->llc_id) {
 			cpumask_set_cpu(cpu, &cpuid_topo->llc_sibling);
 			cpumask_set_cpu(cpuid, &cpu_topo->llc_sibling);
 		}