From patchwork Tue Nov 19 15:34:55 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Valentin Schneider X-Patchwork-Id: 13880158 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 D9D2E1D0F51 for ; Tue, 19 Nov 2024 15:38:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732030690; cv=none; b=bFW5K7BcL5S2dAZEza1sfzmHxvPiT7DNULLqEfwj62cwwG4AYd4LVuW5tWdsTda5JDYBy2PdPUk52xYkmqRDRvkptURrzqOc6/JPznJuWkF/PePYMwbBjaMBE8nqh5HK8z5NKYmLAk47tydhUvNIGY+reSr97TNrCw78JH+OUp8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732030690; c=relaxed/simple; bh=WcoRXmH8EHSSUkrYncG38ywpgNOrSaCBNAPretltWvc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BIAp+9bxbQbG3j1E9dq0+va/roGvt4pCBm8SuNFHJlitreMAargO8fOGEYGg1roeYQ+mtx+0hdvnkh005ZaZ1ro8Ig3c3AYos2MCpbSF+xHilnxrPJdUvOtY8taASqKXxVIe8WosCkmIck2kBFjWqFSEbslvOEglYhedFi5Epqg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=Ksdh/qUf; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Ksdh/qUf" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1732030688; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=lpSGcS2OHkivSptNEqV1yoUV7L+1Tpt77Idg0XadxAw=; b=Ksdh/qUfMGAu3JF60FBMQQA8j5wcLeTDikdgTdcG/3VfJ7rqNBrEJ3w6b83/WBkylTaf9p GJrpI8XeDKN4Qci7qUdjy2EHfJycO42eIA1roL9NZsOV6FOnAKmEdbSABiOKL/AFzDT5yF EgBcphIs5Mu7KHFkPluWl44QWo8zcnk= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-209-w8WZReDNPhuTuNl53MRXLw-1; Tue, 19 Nov 2024 10:38:05 -0500 X-MC-Unique: w8WZReDNPhuTuNl53MRXLw-1 X-Mimecast-MFC-AGG-ID: w8WZReDNPhuTuNl53MRXLw Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 8F25E1955F41; Tue, 19 Nov 2024 15:37:59 +0000 (UTC) Received: from vschneid-thinkpadt14sgen2i.remote.csb (unknown [10.39.194.94]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 59F3B30001A2; Tue, 19 Nov 2024 15:37:44 +0000 (UTC) From: Valentin Schneider To: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org, linux-mm@kvack.org, bpf@vger.kernel.org, x86@kernel.org, rcu@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: Steven Rostedt , Masami Hiramatsu , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , Paolo Bonzini , Wanpeng Li , Vitaly Kuznetsov , Andy Lutomirski , Peter Zijlstra , Frederic Weisbecker , "Paul E. McKenney" , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , Lorenzo Stoakes , Josh Poimboeuf , Jason Baron , Kees Cook , Sami Tolvanen , Ard Biesheuvel , Nicholas Piggin , Juerg Haefliger , Nicolas Saenz Julienne , "Kirill A. Shutemov" , Nadav Amit , Dan Carpenter , Chuang Wang , Yang Jihong , Petr Mladek , "Jason A. Donenfeld" , Song Liu , Julian Pidancet , Tom Lendacky , Dionna Glaze , =?utf-8?q?Thomas_Wei=C3=9Fschuh?= , Juri Lelli , Marcelo Tosatti , Yair Podemsky , Daniel Wagner , Petr Tesarik Subject: [RFC PATCH v3 08/15] sched/clock, x86: Make __sched_clock_stable forceful Date: Tue, 19 Nov 2024 16:34:55 +0100 Message-ID: <20241119153502.41361-9-vschneid@redhat.com> In-Reply-To: <20241119153502.41361-1-vschneid@redhat.com> References: <20241119153502.41361-1-vschneid@redhat.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Later commits will cause objtool to warn about non __ro_after_init static keys being used in .noinstr sections in order to safely defer instruction patching IPIs targeted at NOHZ_FULL CPUs. __sched_clock_stable is used in .noinstr code, and can be modified at runtime (e.g. KVM module loading). Suppressing the text_poke_sync() IPI has little benefits for this key, as NOHZ_FULL is incompatible with an unstable TSC anyway. Mark it as forceful to let the kernel know to always send the text_poke_sync() IPI for it, and to let objtool know not to warn about it. Signed-off-by: Valentin Schneider --- kernel/sched/clock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c index 200e5568b9894..dc94b3717f5ce 100644 --- a/kernel/sched/clock.c +++ b/kernel/sched/clock.c @@ -76,7 +76,7 @@ static DEFINE_STATIC_KEY_FALSE_RO(sched_clock_running); * Similarly we start with __sched_clock_stable_early, thereby assuming we * will become stable, such that there's only a single 1 -> 0 transition. */ -static DEFINE_STATIC_KEY_FALSE(__sched_clock_stable); +static DEFINE_STATIC_KEY_FALSE_FORCE(__sched_clock_stable); static int __sched_clock_stable_early = 1; /*