linux-kernel - [PATCH v2 4/6] powerpc/smp: Disable MC domain for shared processor

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Message-ID: <20231018163751.2423181-5-srikar@linux.vnet.ibm.com>
Date:   Wed, 18 Oct 2023 22:07:44 +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>,
        Christophe Leroy <christophe.leroy@...roup.eu>,
        Nicholas Piggin <npiggin@...il.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Rohan McLure <rmclure@...ux.ibm.com>,
        Valentin Schneider <vschneid@...hat.com>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/6] 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 498c2d51fc20..29da9262cb17 100644
--- a/arch/powerpc/kernel/smp.c
+++ b/arch/powerpc/kernel/smp.c
@@ -1046,6 +1046,10 @@ 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;
 }
 
-- 
2.31.1