From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 0CF23C38A2D for ; Wed, 26 Oct 2022 20:35:38 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1onn6N-0001gu-SR; Wed, 26 Oct 2022 16:34:15 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1onn6I-0001RB-2E for qemu-devel@nongnu.org; Wed, 26 Oct 2022 16:34:11 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1onn6F-0006Fq-Nf for qemu-devel@nongnu.org; Wed, 26 Oct 2022 16:34:09 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1666816445; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=xDK9SpcJnRkQ5dTXycF8Cb/E18YCPCYXacs1p51bQak=; b=DQ6qhewk/puugCbMHvlIBYwcCPdkM0chdR48mQiaWI9asVsbeAx9T8M0V4sxuy25bFfYiA Uih5yIXAUG6Wlo95ZeUeTUltE+do4sw8tHy0LXb0KbrU4b+j6VKIqGsAkkKz6zIdKd1GgE WedD5gfib29R4bm1gC5lydoxGfsiv5c= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-138-fTr-LPzoNoedp8DA8_FbaQ-1; Wed, 26 Oct 2022 16:34:04 -0400 X-MC-Unique: fTr-LPzoNoedp8DA8_FbaQ-1 Received: by mail-wm1-f71.google.com with SMTP id v125-20020a1cac83000000b003bd44dc5242so1593555wme.7 for ; Wed, 26 Oct 2022 13:34:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=xDK9SpcJnRkQ5dTXycF8Cb/E18YCPCYXacs1p51bQak=; b=dec13gYtYDzTz26GrdM4XmRjwrLqJGdc4QZUNMsuB2xkt2Urh5PDaw9Od6OLtBZzBI jtv6bJM/eAyeSARqYcOYSBx/gHqoFj5zTyvX/wmd0KWMusF4pJySaH0HlUQmvXzvdy7y wl9Jd6LQO4XwNNGMt4LvZzrasHJJVPhCdoFglrDG4vHCo8wUIN4fIshmTWsAWoTdjpNi YPQrMdTTa8I9b+nXvpxfSeDRcIKF3PTf1TcKqsJWvxEMEs/96ic+yxKe6nrKAr6V9rKD uQBxGOIV1mmzf1EGYK12u//SRLETlIzUfov7+moqRoVyzFRtvlKURI4jzJFCy6SpvxFd Pd3Q== X-Gm-Message-State: ACrzQf1VagQRhLd85boZZaTEJVXnbOhtWpBa6O/63i2SulUBg+jd4fcB 5wQxdav9foA0crbjawr8JIPVuhXzaacuXJZZUyhq2+NZ6XAkO0cCkNChLWhDJURc8k/GAfTGWyB on/yt5y5QitymtpA= X-Received: by 2002:a5d:6887:0:b0:236:8ead:47ab with SMTP id h7-20020a5d6887000000b002368ead47abmr2753412wru.372.1666816440703; Wed, 26 Oct 2022 13:34:00 -0700 (PDT) X-Google-Smtp-Source: AMsMyM5GmenqTPA7iRI0ZDrJomr1ijVzSUIu6/rEK7vvw1vz1m3nBfwuc2A/W2Cg6xK15egWeXwPrQ== X-Received: by 2002:a5d:6887:0:b0:236:8ead:47ab with SMTP id h7-20020a5d6887000000b002368ead47abmr2753389wru.372.1666816440453; Wed, 26 Oct 2022 13:34:00 -0700 (PDT) Received: from redhat.com ([2.52.15.7]) by smtp.gmail.com with ESMTPSA id bi15-20020a05600c3d8f00b003b497138093sm2589298wmb.47.2022.10.26.13.33.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Oct 2022 13:33:59 -0700 (PDT) Date: Wed, 26 Oct 2022 16:33:56 -0400 From: "Michael S. Tsirkin" To: Gregory Price Cc: qemu-devel@nongnu.org, jonathan.cameron@huawei.com, linux-cxl@vger.kernel.org, marcel.apfelbaum@gmail.com, imammedo@redhat.com, ani@anisinha.ca, alison.schofield@intel.com, dave@stgolabs.net, a.manzanares@samsung.com, bwidawsk@kernel.org, gregory.price@memverge.com, hchkuo@avery-design.com.tw, cbrowy@avery-design.com, ira.weiny@intel.com Subject: Re: [PATCH 1/4] hw/i386/pc.c: CXL Fixed Memory Window should not reserve e820 in bios Message-ID: <20221026163336-mutt-send-email-mst@kernel.org> References: <20221026004737.3646-1-gregory.price@memverge.com> <20221026004737.3646-2-gregory.price@memverge.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221026004737.3646-2-gregory.price@memverge.com> Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -25 X-Spam_score: -2.6 X-Spam_bar: -- X-Spam_report: (-2.6 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.515, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Qemu-devel" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Oct 25, 2022 at 08:47:34PM -0400, Gregory Price wrote: > Early-boot e820 records will be inserted by the bios/efi/early boot > software and be reported to the kernel via insert_resource. Later, when > CXL drivers iterate through the regions again, they will insert another > resource and make the RESERVED memory area a child. > > This RESERVED memory area causes the memory region to become unusable, > and as a result attempting to create memory regions with > > `cxl create-region ...` > > Will fail due to the RESERVED area intersecting with the CXL window. > > During boot the following traceback is observed: > > 0xffffffff81101650 in insert_resource_expand_to_fit () > 0xffffffff83d964c5 in e820__reserve_resources_late () > 0xffffffff83e03210 in pcibios_resource_survey () > 0xffffffff83e04f4a in pcibios_init () > > Which produces a call to reserve the CFMWS area: > > (gdb) p *new > $54 = {start = 0x290000000, end = 0x2cfffffff, name = "Reserved", > flags = 0x200, desc = 0x7, parent = 0x0, sibling = 0x0, > child = 0x0} > > Later the Kernel parses ACPI tables and reserves the exact same area as > the CXL Fixed Memory Window: > > 0xffffffff811016a4 in insert_resource_conflict () > insert_resource () > 0xffffffff81a81389 in cxl_parse_cfmws () > 0xffffffff818c4a81 in call_handler () > acpi_parse_entries_array () > > (gdb) p/x *new > $59 = {start = 0x290000000, end = 0x2cfffffff, name = "CXL Window 0", > flags = 0x200, desc = 0x0, parent = 0x0, sibling = 0x0, > child = 0x0} > > This produces the following output in /proc/iomem: > > 590000000-68fffffff : CXL Window 0 > 590000000-68fffffff : Reserved > > This reserved area causes `get_free_mem_region()` to fail due to a check > against `__region_intersects()`. Due to this reserved area, the > intersect check will only ever return REGION_INTERSECTS, which causes > `cxl create-region` to always fail. > > Signed-off-by: Gregory Price Do we want this as a bugfix, separate from the rest of the patchset? > --- > hw/i386/pc.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index 768982ae9a..203c90fedb 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -1062,7 +1062,6 @@ void pc_memory_init(PCMachineState *pcms, > hwaddr cxl_size = MiB; > > cxl_base = pc_get_cxl_range_start(pcms); > - e820_add_entry(cxl_base, cxl_size, E820_RESERVED); > memory_region_init(mr, OBJECT(machine), "cxl_host_reg", cxl_size); > memory_region_add_subregion(system_memory, cxl_base, mr); > cxl_resv_end = cxl_base + cxl_size; > @@ -1078,7 +1077,6 @@ void pc_memory_init(PCMachineState *pcms, > memory_region_init_io(&fw->mr, OBJECT(machine), &cfmws_ops, fw, > "cxl-fixed-memory-region", fw->size); > memory_region_add_subregion(system_memory, fw->base, &fw->mr); > - e820_add_entry(fw->base, fw->size, E820_RESERVED); > cxl_fmw_base += fw->size; > cxl_resv_end = cxl_fmw_base; > } > -- > 2.37.3