From nobody Sat Jul 25 01:37:24 2026 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) (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 8066E78F26; Tue, 21 Jul 2026 03:21:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=193.142.43.55 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784604118; cv=none; b=YAi86ULJ05Y9HzqXC7voZdv2GpbrFlaP3eErj5Tvr/kiBEhhpqaJQb+Pkqy5FSqCpXiI69xVrAUV6qvTz7TqxWVnQSmHrro7TCMUTrj16f6FPBHzUDFZ5q9+mCNjMqfoD7tv4IyDPPyM7BxWgnn6SVyWk0R/9mif9AEzQm94Qbo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784604118; c=relaxed/simple; bh=3WGCdkfa2OpyblJ9wkhLisnxVb/ccolRM36TiVOGjCE=; h=Date:From:To:Subject:Cc:In-Reply-To:References:MIME-Version: Message-ID:Content-Type; b=XDMpp2VNAI3hJ+ZjDH83RMhIElB1PDVxzyocVd1LkQPiFvUwLDiw1MCQ4LG//RR7K2Fdrx8EvaWtcOKps7XKA5llWE+Q55zHE535sXl0rSF9A3mn+Tybnur+yAKf3S1cZbzIxvLjqmuXdNWT0f3OKl4JEW/aWtY3pdPshHwCAyw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de; spf=pass smtp.mailfrom=linutronix.de; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=zunq4vmN; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b=dYIdUi+h; arc=none smtp.client-ip=193.142.43.55 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linutronix.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linutronix.de Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="zunq4vmN"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="dYIdUi+h" Date: Tue, 21 Jul 2026 03:21:53 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1784604115; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=83bulp1rlE+OByhKy1bkFa4QcWqRUIA9Mbdym+ZLF7E=; b=zunq4vmNp9cOWAREekCae8I5SkjYvXdsrXuQH+VUoNl8sN45cg5Gg5JsmvUreVyvwwIYf6 tjv8xqe1j61ksTkBz4e3mUacfrdi19a356+lk7M1S2XahZSqVzf/+hyLVWqRq3qNEhwjNw J9xWJ4rcOmJ7VjpDIslvzORvp41lgGHoGe7EpcLcFW9epNG4V5b/sOSD0iy+B/f0yzNDwe A8Yo9sekkfLDwR/9240mhp43FgJQ7rmcSWammAQ5aky6akNcYY42XzRszjawkJrTXA9OT8 M6qkvEiAg28zia8lcb0VtkzMwP1lgLOiWNUYBS8chvBAX1tk19R+tRYxT0/Fug== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1784604115; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=83bulp1rlE+OByhKy1bkFa4QcWqRUIA9Mbdym+ZLF7E=; b=dYIdUi+hcQXcRvmUuqiMhCQhKnZjkl5b89yFBIS6i89EXdIBzQsIOHvjXHxRvs82aLU9Vh DErds/yehuSEI3AQ== From: "tip-bot2 for Tim Wiederhake" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: x86/cleanups] x86/msr: Document the I/O-like write semantics in the msr driver Cc: Tim Wiederhake , "Borislav Petkov (AMD)" , x86@kernel.org, linux-kernel@vger.kernel.org In-Reply-To: <20260629173759.1770596-1-twiederh@redhat.com> References: <20260629173759.1770596-1-twiederh@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-ID: <178460411333.2943223.4295359564100832979.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable The following commit has been merged into the x86/cleanups branch of tip: Commit-ID: b096d79bc1eed9eda57c12ccd76d6797cdba4cf2 Gitweb: https://git.kernel.org/tip/b096d79bc1eed9eda57c12ccd76d6797c= dba4cf2 Author: Tim Wiederhake AuthorDate: Mon, 29 Jun 2026 19:37:59 +02:00 Committer: Borislav Petkov (AMD) CommitterDate: Mon, 20 Jul 2026 19:57:33 -07:00 x86/msr: Document the I/O-like write semantics in the msr driver Explain why msr_write() does not advance the index. [ bp: Massage commit message. ] Signed-off-by: Tim Wiederhake Signed-off-by: Borislav Petkov (AMD) Link: https://patch.msgid.link/20260629173759.1770596-1-twiederh@redhat.com --- arch/x86/kernel/msr.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c index 34bdb75..eb988df 100644 --- a/arch/x86/kernel/msr.c +++ b/arch/x86/kernel/msr.c @@ -13,6 +13,9 @@ * and then read/write in chunks of 8 bytes. A larger size means multiple * reads or writes of the same register. * + * Writing the same register multiple times can be useful for MSRs with + * I/O-like semantics, e.g. a virtual MSR that accepts logging information. + * * This driver uses /dev/cpu/%d/msr where %d is the minor number, and on * an SMP box will direct the access to CPU %d. */