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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 316F9C433E0 for ; Wed, 3 Mar 2021 09:51:17 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 820EE64EE6 for ; Wed, 3 Mar 2021 09:51:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 820EE64EE6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:59158 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lHO9z-0004Te-BH for qemu-devel@archiver.kernel.org; Wed, 03 Mar 2021 04:51:15 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:57524) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lHO8r-000384-Mm for qemu-devel@nongnu.org; Wed, 03 Mar 2021 04:50:05 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:47900) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lHO8p-0001YE-Jh for qemu-devel@nongnu.org; Wed, 03 Mar 2021 04:50:05 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1614765002; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ihElrn+t6ag1ibheZwGJgCKfrfjwAWAnm87G605MEVE=; b=WyqUu2tSV+lLi55d/DJ/U7tjFE5kD/GIV4j5lJEIAmBtYffewdD6CO8SB8qjxCfcBhy5TJ dioidA8W43jBf4KS6ASq7TTMHyQBv9YxwS98k8+T3+MF7HPNpiFStA41d40dl8v/Wf6R6I GVL+Z2YteQ1ZtcaJcIxhsJGHM0IKL4E= 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-587-4QZO-A4aMTePZy8HHLTktw-1; Wed, 03 Mar 2021 04:49:58 -0500 X-MC-Unique: 4QZO-A4aMTePZy8HHLTktw-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B38ADC29F; Wed, 3 Mar 2021 09:49:50 +0000 (UTC) Received: from [10.36.112.28] (ovpn-112-28.ams2.redhat.com [10.36.112.28]) by smtp.corp.redhat.com (Postfix) with ESMTP id 81FC219C48; Wed, 3 Mar 2021 09:49:48 +0000 (UTC) Subject: Re: [PATCH v1] acpi: increase maximum size for "etc/table-loader" blob To: "Michael S. Tsirkin" References: <20210301104833.45580-1-david@redhat.com> <20210302172323.6cac394a@MiWiFi-RA69-srv> <09fbdaa9-2882-2056-a5a2-2ca0da8c12cf@redhat.com> <7d8281a8-0479-ac81-c602-ed87c71ce3e2@redhat.com> <20210303044336-mutt-send-email-mst@kernel.org> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Wed, 3 Mar 2021 10:49:47 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <20210303044336-mutt-send-email-mst@kernel.org> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=david@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=216.205.24.124; envelope-from=david@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , Richard Henderson , qemu-devel@nongnu.org, Alistair Francis , Shannon Zhao , qemu-arm@nongnu.org, Paolo Bonzini , Igor Mammedov , Laszlo Ersek Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 03.03.21 10:43, Michael S. Tsirkin wrote: > On Tue, Mar 02, 2021 at 07:43:40PM +0100, David Hildenbrand wrote: >>>>> The resizeable memory region that is created for the cmd blob has a maximum >>>>> size of ACPI_BUILD_ALIGN_SIZE - 4k. This used to be sufficient, however, >>> >>> The expression "ACPI_BUILD_ALIGN_SIZE - 4k" makes no sense to me. >>> ACPI_BUILD_ALIGN_SIZE is #defined in "hw/i386/acpi-build.c" as 0x1000, >>> so the difference (ACPI_BUILD_ALIGN_SIZE - 4k) is zero. >>> >>> (1) Did you mean "ACPI_BUILD_ALIGN_SIZE -- 4k"? IOW, did you mean to >>> quote the value of the macro? >>> >>> If you mean an em dash, then please use an em dash, not a hyphen (or >>> please use parens). >> >> Yes, or rather use ACPI_BUILD_ALIGN_SIZE (4k). >> >>> >>> >>>>> as we try fitting in additional data (e.g., vmgenid, nvdimm, intel-iommu), >>>>> we require more than 4k and can crash QEMU when trying to resize the >>>>> resizeable memory region beyond its maximum size: >>>>> $ build/qemu-system-x86_64 --enable-kvm \ >>>>> -machine q35,nvdimm=on \ >>>>> -smp 1 \ >>>>> -cpu host \ >>>>> -m size=2G,slots=8,maxmem=4G \ >>>>> -object memory-backend-file,id=mem0,mem-path=/tmp/nvdimm,size=256M \ >>>>> -device nvdimm,label-size=131072,memdev=mem0,id=nvdimm0,slot=1 \ >>>>> -nodefaults \ >>>>> -device vmgenid \ >>>>> -device intel-iommu >>>>> >>>>> Results in: >>>>> Unexpected error in qemu_ram_resize() at ../softmmu/physmem.c:1850: >>>>> qemu-system-x86_64: Size too large: /rom@etc/table-loader: >>>>> 0x2000 > 0x1000: Invalid argument >>>>> >>>>> We try growing the resizeable memory region (resizeable RAMBlock) beyond >>>>> its maximum size. Let's increase the maximum size from 4k to 64k, which >>>>> should be good enough for the near future. >>> >>> The existent code calls acpi_align_size(), for resizing the ACPI blobs >>> (the GArray objects). >>> >>> (Unfortunately, the acpi_align_size() function is duplicated between >>> "hw/i386/acpi-build.c" and "hw/arm/virt-acpi-build.c", which seems >>> unjustified -- but anyway, I digress.) >>> >>> This seems to come from commit 868270f23d8d ("acpi-build: tweak acpi >>> migration limits", 2014-07-29) and commit 451b157041d2 ("acpi: Align the >>> size to 128k", 2020-12-08). >>> >>> (2) Why is the logic added in those commits insufficient? >> >> We are dealing with different blobs here (tables_blob vs. cmd_blob). >> >>> >>> What is the exact call tree that triggers the above error? >> >> [...] >> >> acpi_build_update()->acpi_build_update()->memory_region_ram_resize()->qemu_ram_resize() >> >> A longer calltrace can be found in https://bugzilla.redhat.com/show_bug.cgi?id=1927159. >> >>>>> +++ b/hw/i386/acpi-microvm.c >>>>> @@ -255,7 +255,8 @@ void acpi_setup_microvm(MicrovmMachineState *mms) >>>>> ACPI_BUILD_TABLE_MAX_SIZE); >>>>> acpi_add_rom_blob(acpi_build_no_update, NULL, >>>>> tables.linker->cmd_blob, >>>>> - "etc/table-loader", 0); >>>>> + ACPI_BUILD_LOADER_FILE, >>>>> + ACPI_BUILD_LOADER_MAX_SIZE); >>>>> acpi_add_rom_blob(acpi_build_no_update, NULL, >>>>> tables.rsdp, >>>>> ACPI_BUILD_RSDP_FILE, 0); >>> >>> (3) Why are we using a different "tool" here, from the previous >>> approach? We're no longer setting the GArray sizes; instead, we make the >>> "rom->romsize" fields diverge from -- put differently, grow beyond -- >>> "rom->datasize". Why is that useful? What are the consequences? >> >> See ACPI_BUILD_TABLE_MAX_SIZE handling just in the acpi_add_rom_blob() above. >> >>> >>> Where is it ensured that data between "rom->datasize" and "rom->romsize" >>> reads as zeroes? >> We only expose the current memory_region_size() to our guest, which is >> always multiples of 4k pages. >> >> rom->datasize and rom->romsize will be multiple of 4k AFAIKs. >> >> acpi_align_size()-> g_array_set_size() will take care of zeroing out >> any unused parts within a single 4k page. >> >> So all unused, guest-visible part should always be 0 I think. >> >>> >>> >>>>> diff --git a/include/hw/acpi/aml-build.h b/include/hw/acpi/aml-build.h >>>>> index 380d3e3924..93cdfd4006 100644 >>>>> --- a/include/hw/acpi/aml-build.h >>>>> +++ b/include/hw/acpi/aml-build.h >>>>> @@ -6,6 +6,7 @@ >>>>> >>>>> /* Reserve RAM space for tables: add another order of magnitude. */ >>>>> #define ACPI_BUILD_TABLE_MAX_SIZE 0x200000 >>>>> +#define ACPI_BUILD_LOADER_MAX_SIZE 0x40000 >>>>> >>>>> #define ACPI_BUILD_APPNAME6 "BOCHS " >>>>> #define ACPI_BUILD_APPNAME8 "BXPC " >>>> >>> >>> The commit message says "Let's increase the maximum size from 4k to >>> 64k", and I have two problems with that: >>> >>> (4a) I have no idea where the current "4k" size comes from. (In case the >>> 4k refers to ACPI_BUILD_ALIGN_SIZE, then why are we not changing that >>> macro?) >> >> Changing ACPI_BUILD_ALIGN_SIZE would affect the legacy_table_size in >> acpi_build() - so that can't be right. >> >> What would also work is something like (to be improved) >> >> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c >> index 45ad2f9533..49cfedddc8 100644 >> --- a/hw/i386/acpi-build.c >> +++ b/hw/i386/acpi-build.c >> @@ -81,6 +81,8 @@ >> #define ACPI_BUILD_LEGACY_CPU_AML_SIZE 97 >> #define ACPI_BUILD_ALIGN_SIZE 0x1000 >> +#define ACPI_BUILD_LOADER_ALIGN_SIZE 0x2000 >> + >> #define ACPI_BUILD_TABLE_SIZE 0x20000 >> /* #define DEBUG_ACPI_BUILD */ >> @@ -2613,10 +2615,10 @@ void acpi_build(AcpiBuildTables *tables, MachineState *machine) >> error_printf("Try removing CPUs, NUMA nodes, memory slots" >> " or PCI bridges."); >> } >> - acpi_align_size(tables_blob, ACPI_BUILD_TABLE_SIZE); >> + acpi_align_size(tables_blob, ACPI_BUILD_ALIGN_SIZE); >> } >> - acpi_align_size(tables->linker->cmd_blob, ACPI_BUILD_ALIGN_SIZE); >> + acpi_align_size(tables->linker->cmd_blob, ACPI_BUILD_LOADER_ALIGN_SIZE); >> >> >> At least for hw/i386/acpi-build.c. >> >> We will end up creating the resizeable memory region/RAMBlock always with >> a size=maximum_size=8k. (could also go for 64k here) >> >> The only downside is that we might expose a bigger area to the >> guest than necessary (e.g., 8k instead of 4k) and will e.g., migrate >> 8k instead of 4k (not that we care). >> >> >> On incoming migration from older QEMU versions, we should be able to just >> shrink back from 8k to 4k - so migration from older QEMY versions should >> continue working just fine. > > what about migration to old qemu? We seem to have replied at just the same time. See my other mail :) -- Thanks, David / dhildenb