linux-kernel - [PATCH 4/4] powerpc/smp: Disable MC domain for shared processor

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Date:   Wed, 30 Aug 2023 16:22:44 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        Juergen Gross <jgross@...e.com>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Paul E McKenney <paulmck@...nel.org>,
        Valentin Schneider <vschneid@...hat.com>,
        Nathan Lynch <nathanl@...ux.ibm.com>,
        virtualization@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] powerpc/smp: Disable MC domain for shared processor

Like L2-cache info, coregroup information which is used to determine MC
sched domains is only present on dedicated LPARs. i.e PowerVM doesn't
export coregroup information for shared processor LPARs. Hence disable
creating MC domains on shared LPAR Systems.

Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
---
 arch/powerpc/kernel/smp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
index 51403640440c..48b8161179a8 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1036,6 +1036,10 @@ static struct cpumask *cpu_coregroup_mask(int cpu)
 
 static bool has_coregroup_support(void)
 {
+	/* Coregroup identification not available on shared systems */
+	if (is_shared_processor())
+		return 0;
+
 	return coregroup_enabled;
 }
 
-- 
2.41.0