linux-kernel - [PATCH v5 2/5] powerpc/smp: Disable MC domain for shared processor

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Message-ID: <20231214180720.310852-3-srikar@linux.vnet.ibm.com>
Date:   Thu, 14 Dec 2023 23:37:12 +0530
From:   Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Nicholas Piggin <npiggin@...il.com>,
        Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        linux-kernel@...r.kernel.org, Mark Rutland <mark.rutland@....com>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Rohan McLure <rmclure@...ux.ibm.com>,
        Valentin Schneider <vschneid@...hat.com>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Aneesh <aneesh.kumar@...nel.org>,
        "ndesaulniers@...gle.com" <ndesaulniers@...gle.com>
Subject: [PATCH v5 2/5] 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 3fc8ad9646a4..2cebc53e97f9 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1055,6 +1055,10 @@ 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;
 }
 
-- 
2.35.3