From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 50E0B3A1E86; Thu, 15 Jan 2026 17:15:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768497356; cv=none; b=h3LtiV/C2iYYz+2Z5oNzQOnmtomFOdTmfkL43jyb27XMhQGdGrb49ITlFBWx9fkw4WYNivAFaST581o02DIdAVCmBhae6YA3PeFFt9oMKl08nys8MsCRzpgtHbgvoBACLdtdf6VPo5u1fR0RsF3iljJ+5Y+NvInHc0aLtGV3KNQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768497356; c=relaxed/simple; bh=0q2AknPaMMTOQLZGrCcadY88WjzcwYrsFOsOFQZdFaA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tT1qBxAwuP3i8BLqYGWDm9IL+pqxhdj4ICFQNCq3PLwYljOSX7LksbS6e3vtJFuAN+9BlhVbBhFqz6nTCFoY1ivjk3nYgCtHmBfWuPHqyq/sLxZ48WGdfGjgW3bQJPrzix1hX5jAAX5+5gJCKnf79OgFZE4psoVRtn2cnHlr1Hg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LGYqOXVZ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="LGYqOXVZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C84F4C116D0; Thu, 15 Jan 2026 17:15:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1768497356; bh=0q2AknPaMMTOQLZGrCcadY88WjzcwYrsFOsOFQZdFaA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LGYqOXVZSoj1SyUi3Tx8y5qKrFjpWk2kq+hXznWc2PbwKOg+yO4odRzHSrXCmpg+T RgwgxktkMvyi1L8VvwmrQ2cT3k+SGV+Tx2tQwUdnc5hN7diCISQSEl5OML12Rjd/Oq fky6/uBFKrjZ7BHGzyaYdWJ1G85re0mc4Ezh7TOs= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alexander Egorenkov , Mete Durlu , Heiko Carstens , Sasha Levin Subject: [PATCH 5.15 052/554] s390/smp: Fix fallback CPU detection Date: Thu, 15 Jan 2026 17:41:58 +0100 Message-ID: <20260115164248.128947265@linuxfoundation.org> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20260115164246.225995385@linuxfoundation.org> References: <20260115164246.225995385@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Heiko Carstens [ Upstream commit 07a75d08cfa1b883a6e1256666e5f0617ee99231 ] In case SCLP CPU detection does not work a fallback mechanism using SIGP is in place. Since a cleanup this does not work correctly anymore: new CPUs are only considered if their type matches the boot CPU. Before the cleanup the information if a CPU type should be considered was also part of a structure generated by the fallback mechanism and indicated that a CPU type should not be considered when adding CPUs. Since the rework a global SCLP state is used instead. If the global SCLP state indicates that the CPU type should be considered and the fallback mechanism is used, there may be a mismatch with CPU types if CPUs are added. This can lead to a system with only a single CPU even tough there are many more CPUs. Address this by simply copying the boot cpu type into the generated data structure from the fallback mechanism. Reported-by: Alexander Egorenkov Fixes: d08d94306e90 ("s390/smp: cleanup core vs. cpu in the SCLP interface") Reviewed-by: Mete Durlu Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin --- arch/s390/kernel/smp.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 5c1fd147591cb..824941e3204d7 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -754,6 +754,7 @@ static void __ref smp_get_core_info(struct sclp_core_info *info, int early) continue; info->core[info->configured].core_id = address >> smp_cpu_mt_shift; + info->core[info->configured].type = boot_core_type; info->configured++; } info->combined = info->configured; -- 2.51.0