From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from m16.mail.163.com (m16.mail.163.com [220.197.31.4]) (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 3ACD91B4F1F for ; Sat, 11 Apr 2026 11:18:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=220.197.31.4 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775906327; cv=none; b=WqX3jYC3MvM7Gt73gpqKNbnKjSQYMjmQNkU758Q1Tp6pfysg01Sf7VW7tpJ+1m3V1x9oLgDHwU0gDs5uTyVNfvSnm93/S3HQgvLArWGI76pIG+pZrXPWRqJEX74xY4I0w57Nvi4NU646tIQHxUG2+h9Mp5Umu+qacJq8dBbMGTM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775906327; c=relaxed/simple; bh=cS5Oq2RwIaNoZCIObzP+FnEafURtHU3cUW5wY3svEHk=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=TuGBKM1hczShOpunh7ah1O3pEZyLlomsYMZIxEoxMWEsmZWrcIV+l0R6T+RfBnCyAS1UHXWdUSNOUAON9KMsE6YEUpw9brQXUR8UlydZzvaNgj7BPGlsF109+HF1A91+5Bl+G+03uQsG5PCmFto1fNEggOCoyPWyU4euZy9lfls= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com; spf=pass smtp.mailfrom=163.com; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b=pJ3tSDwZ; arc=none smtp.client-ip=220.197.31.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=163.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=163.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=163.com header.i=@163.com header.b="pJ3tSDwZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=163.com; s=s110527; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=nw +quAlx126idSVAuFnSjo5KYb3zAUCidiHA9hPIOk0=; b=pJ3tSDwZHKu6BRlRTx iZ74JE17UrTJXSZf9j5mSQ6HZWXaL1dkkfrfbPNQYNmFeEEsUoO0uQndCM29pFBO XSfi4GOjsQwYlZF8cbxDHFmaGx+yPR+VKlOv5NoWS+N2h07RkWF2pUMGe9ZKgFVM /44o7ihuPdcANneGhpNrmGoys= Received: from localhost.localdomain (unknown []) by gzga-smtp-mtada-g0-4 (Coremail) with SMTP id _____wCnnqbRLdppAHYpEg--.36044S2; Sat, 11 Apr 2026 19:17:39 +0800 (CST) From: Cao Ruichuang To: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H . Peter Anvin" , linux-kernel@vger.kernel.org Cc: akinzler Subject: [PATCH] x86/itmt: Keep ITMT enabled when debugfs is unavailable Date: Sat, 11 Apr 2026 19:17:31 +0800 Message-Id: <20260411111731.33822-1-create0818@163.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CM-TRANSID:_____wCnnqbRLdppAHYpEg--.36044S2 X-Coremail-Antispam: 1Uf129KBjvJXoWxXF48ur4xCr47Cr4fCFyUWrg_yoW5Gw4rp3 yvgw45Gry8trnxK3y3Ar48XFyrA397ury7Wrnru3yxZw15Jr1rWr10kF4avFZxWa1jkrWS yr1YkasrXr1UtaDanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDUYxBIdaVFxhVjvjDU0xZFpf9x07jYKZXUUUUU= X-CM-SenderInfo: pfuht3jhqyimi6rwjhhfrp/xtbCvxaRymnaLdb62QAA3Z SCHED_MC_PRIO should not depend on DEBUG_FS for its runtime behavior. debugfs_create_file*() intentionally returns -ENODEV when CONFIG_DEBUG_FS is disabled so callers can distinguish "debugfs unavailable" from a real error. sched_set_itmt_support() currently treats that case as fatal and returns an error before enabling ITMT support. As a result, systems built with SCHED_MC_PRIO=y and DEBUG_FS=n silently lose ITMT scheduling support even though the two debugfs files created in itmt.c are only a debug toggle and a debug view of core priorities. Treat -ENODEV from the debugfs helpers as "no debugfs support" and keep going. Continue to fail on real debugfs creation errors. Fixes: d04013a4b21b ("x86/itmt: Move the "sched_itmt_enabled" sysctl to debugfs") Reported-by: akinzler Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220638 Signed-off-by: Cao Ruichuang --- Testing: - latest-tree local compile validation with `CONFIG_DEBUG_FS=n` succeeded (`CC arch/x86/kernel/itmt.o`) Note: - meaningful local runtime validation is not currently possible here because the available host and guest CPUs are older Ivy Bridge parts, not ITMT-capable Intel hybrid systems arch/x86/kernel/itmt.c | 19 +++++++++++++++++-- 1 file changed, 17 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/itmt.c b/arch/x86/kernel/itmt.c index 243a769fdd9..c3e40df7da7 100644 --- a/arch/x86/kernel/itmt.c +++ b/arch/x86/kernel/itmt.c @@ -100,6 +100,8 @@ static struct dentry *dfs_sched_core_prio; */ int sched_set_itmt_support(void) { + int ret; + guard(mutex)(&itmt_update_mutex); if (sched_itmt_capable) @@ -110,16 +112,29 @@ int sched_set_itmt_support(void) arch_debugfs_dir, &sysctl_sched_itmt_enabled, &dfs_sched_itmt_fops); - if (IS_ERR_OR_NULL(dfs_sched_itmt)) { + if (IS_ERR(dfs_sched_itmt)) { + ret = PTR_ERR(dfs_sched_itmt); dfs_sched_itmt = NULL; + if (ret != -ENODEV) + return ret; + } else if (!dfs_sched_itmt) { return -ENOMEM; } dfs_sched_core_prio = debugfs_create_file("sched_core_priority", 0644, arch_debugfs_dir, NULL, &sched_core_priority_fops); - if (IS_ERR_OR_NULL(dfs_sched_core_prio)) { + if (IS_ERR(dfs_sched_core_prio)) { + ret = PTR_ERR(dfs_sched_core_prio); dfs_sched_core_prio = NULL; + if (ret != -ENODEV) { + debugfs_remove(dfs_sched_itmt); + dfs_sched_itmt = NULL; + return ret; + } + } else if (!dfs_sched_core_prio) { + debugfs_remove(dfs_sched_itmt); + dfs_sched_itmt = NULL; return -ENOMEM; } -- 2.39.5 (Apple Git-154)