From patchwork Thu Apr 30 10:29:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 11519799 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id EFE4C14B4 for ; Thu, 30 Apr 2020 10:29:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D87462137B for ; Thu, 30 Apr 2020 10:29:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GRc1AOxP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726859AbgD3K37 (ORCPT ); Thu, 30 Apr 2020 06:29:59 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:40738 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726852AbgD3K35 (ORCPT ); Thu, 30 Apr 2020 06:29:57 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588242596; 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=cBxdneYzv1oFt6rUtmxHP8L8tmn6FMG5Rn0MO+hCbf0=; b=GRc1AOxPVSP5nuHEWrXjyi/msXQ0zbqJmYJrnrUMnBMgWRZeMevzIvGaFLkugFIFcgkVrV QVgvBqje0bXGeEMvcM98GRSr1ODO6I1j6l2GA54ykkDm7wIHNH/tL3iW/6Q7blEJBradq6 erGTZhdH6d8APCUbHXTN2O1RqAEuTzA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-323-ZkDsTUQ-OxW7sjqOoV_anw-1; Thu, 30 Apr 2020 06:29:51 -0400 X-MC-Unique: ZkDsTUQ-OxW7sjqOoV_anw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 920BB45F; Thu, 30 Apr 2020 10:29:49 +0000 (UTC) Received: from t480s.redhat.com (ovpn-113-172.ams2.redhat.com [10.36.113.172]) by smtp.corp.redhat.com (Postfix) with ESMTP id B43035EDEB; Thu, 30 Apr 2020 10:29:40 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-acpi@vger.kernel.org, linux-nvdimm@lists.01.org, linux-hyperv@vger.kernel.org, linux-s390@vger.kernel.org, xen-devel@lists.xenproject.org, Michal Hocko , Andrew Morton , "Michael S . Tsirkin" , David Hildenbrand , Michal Hocko , Pankaj Gupta , Wei Yang , Baoquan He , Eric Biederman Subject: [PATCH v2 2/3] mm/memory_hotplug: Introduce MHP_NO_FIRMWARE_MEMMAP Date: Thu, 30 Apr 2020 12:29:07 +0200 Message-Id: <20200430102908.10107-3-david@redhat.com> In-Reply-To: <20200430102908.10107-1-david@redhat.com> References: <20200430102908.10107-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org Some devices/drivers that add memory via add_memory() and friends (e.g., dax/kmem, but also virtio-mem in the future) don't want to create entries in /sys/firmware/memmap/ - primarily to hinder kexec from adding this memory to the boot memmap of the kexec kernel. In fact, such memory is never exposed via the firmware memmap as System RAM (e.g., e820), so exposing this memory via /sys/firmware/memmap/ is wrong: "kexec needs the raw firmware-provided memory map to setup the parameter segment of the kernel that should be booted with kexec. Also, the raw memory map is useful for debugging. For that reason, /sys/firmware/memmap is an interface that provides the raw memory map to userspace." [1] We don't have to worry about firmware_map_remove() on the removal path. If there is no entry, it will simply return with -EINVAL. [1] https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-firmware-memmap Cc: Andrew Morton Cc: Michal Hocko Cc: Pankaj Gupta Cc: Wei Yang Cc: Baoquan He Cc: Eric Biederman Signed-off-by: David Hildenbrand Nacked-by: "Eric W. Biederman" --- include/linux/memory_hotplug.h | 8 ++++++++ mm/memory_hotplug.c | 3 ++- 2 files changed, 10 insertions(+), 1 deletion(-) diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 0151fb935c09..4ca418a731eb 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -68,6 +68,14 @@ struct mhp_params { pgprot_t pgprot; }; +/* Flags used for add_memory() and friends. */ + +/* + * Don't create entries in /sys/firmware/memmap/. The memory is detected and + * added via a device driver, not via the initial (firmware) memmap. + */ +#define MHP_NO_FIRMWARE_MEMMAP 1 + /* * Zone resizing functions * diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index c01be92693e3..e94ede9cad00 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1062,7 +1062,8 @@ int __ref add_memory_resource(int nid, struct resource *res, BUG_ON(ret); /* create new memmap entry */ - firmware_map_add_hotplug(start, start + size, "System RAM"); + if (!(flags & MHP_NO_FIRMWARE_MEMMAP)) + firmware_map_add_hotplug(start, start + size, "System RAM"); /* device_online() will take the lock when calling online_pages() */ mem_hotplug_done();