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[209.51.188.17]) by mx.google.com with ESMTPS id v19si2353492uap.204.2021.03.09.07.26.55 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Tue, 09 Mar 2021 07:26:55 -0800 (PST) Received-SPF: pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; dkim=fail header.i=@redhat.com header.s=mimecast20190719 header.b=Y8T3thRb; spf=pass (google.com: domain of qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from localhost ([::1]:59814 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lJeG6-00052q-Iu for alex.bennee@linaro.org; Tue, 09 Mar 2021 10:26:54 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:47588) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lJdc4-0007IB-PD for qemu-devel@nongnu.org; Tue, 09 Mar 2021 09:45:32 -0500 Received: from us-smtp-delivery-124.mimecast.com ([63.128.21.124]:45958) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lJdc1-0005uQ-Rl for qemu-devel@nongnu.org; Tue, 09 Mar 2021 09:45:32 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615301128; 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=KVTw4auZoA1sQ5f6tNBsrZgImX3Q8mIkVMkXXJga3ko=; b=Y8T3thRbJo38s0K7pA9MnEzvHgKl+Fi5VDdaLz2cDhMEZZfmOyz3jint9txTzgnH3Fy7MF xlYaqLH8oLXQMvHi/BOM0SO86/NBU6dUP6ylD3s/V4St4cpOeIDLwgKur5t643P/TIZuY0 02m3Bid5GlaTsWxVqPV+QFuYbFVz4Qo= 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-562-1-DLu99kMwyqQA-IFoMSFA-1; Tue, 09 Mar 2021 09:45:27 -0500 X-MC-Unique: 1-DLu99kMwyqQA-IFoMSFA-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id C1274800D62; Tue, 9 Mar 2021 14:45:25 +0000 (UTC) Received: from thuth.remote.csb (ovpn-112-40.ams2.redhat.com [10.36.112.40]) by smtp.corp.redhat.com (Postfix) with ESMTP id 762AD5C233; Tue, 9 Mar 2021 14:45:14 +0000 (UTC) Subject: Re: [PATCH v2 2/2] accel: kvm: Add aligment assert for kvm_log_clear_one_slot To: Keqian Zhu , Peter Maydell , Paolo Bonzini , "Dr . David Alan Gilbert" , Andrew Jones , Peter Xu , Gerd Hoffmann References: <20201217014941.22872-1-zhukeqian1@huawei.com> <20201217014941.22872-3-zhukeqian1@huawei.com> <65c92236-5212-f725-047a-cb1d231eff25@redhat.com> <759785ef-f29e-f05f-9f2f-357e71ae3680@huawei.com> From: Thomas Huth Message-ID: <11854ebf-ed88-496d-8381-5385ef1b403a@redhat.com> Date: Tue, 9 Mar 2021 15:45:13 +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: <759785ef-f29e-f05f-9f2f-357e71ae3680@huawei.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=thuth@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=63.128.21.124; envelope-from=thuth@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -29 X-Spam_score: -3.0 X-Spam_bar: --- X-Spam_report: (-3.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.251, 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_H4=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: Zenghui Yu , wanghaibin.wang@huawei.com, jiangkunkun@huawei.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org Errors-To: qemu-devel-bounces+alex.bennee=linaro.org@nongnu.org Sender: "Qemu-devel" X-TUID: S5xw6d3nDMZZ On 09/03/2021 15.05, Keqian Zhu wrote: > > > On 2021/3/9 21:48, Thomas Huth wrote: >> On 17/12/2020 02.49, Keqian Zhu wrote: >>> The parameters start and size are transfered from QEMU memory >>> emulation layer. It can promise that they are TARGET_PAGE_SIZE >>> aligned. However, KVM needs they are qemu_real_page_size aligned. >>> >>> Though no caller breaks this aligned requirement currently, we'd >>> better add an explicit assert to avoid future breaking. >>> >>> Signed-off-by: Keqian Zhu >>> --- >>> accel/kvm/kvm-all.c | 7 +++++++ >>> 1 file changed, 7 insertions(+) >>> >>> --- >>> v2 >>> - Address Andrew's commment (Use assert instead of return err). >>> >>> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c >>> index f6b16a8df8..73b195cc41 100644 >>> --- a/accel/kvm/kvm-all.c >>> +++ b/accel/kvm/kvm-all.c >>> @@ -692,6 +692,10 @@ out: >>> #define KVM_CLEAR_LOG_ALIGN (qemu_real_host_page_size << KVM_CLEAR_LOG_SHIFT) >>> #define KVM_CLEAR_LOG_MASK (-KVM_CLEAR_LOG_ALIGN) >>> +/* >>> + * As the granule of kvm dirty log is qemu_real_host_page_size, >>> + * @start and @size are expected and restricted to align to it. >>> + */ >>> static int kvm_log_clear_one_slot(KVMSlot *mem, int as_id, uint64_t start, >>> uint64_t size) >>> { >>> @@ -701,6 +705,9 @@ static int kvm_log_clear_one_slot(KVMSlot *mem, int as_id, uint64_t start, >>> unsigned long *bmap_clear = NULL, psize = qemu_real_host_page_size; >>> int ret; >>> + /* Make sure start and size are qemu_real_host_page_size aligned */ >>> + assert(QEMU_IS_ALIGNED(start | size, psize)); >> >> Sorry, but that was a bad idea: It triggers and kills my Centos 6 VM: >> >> $ qemu-system-x86_64 -accel kvm -hda ~/virt/images/centos6.qcow2 -m 1G >> qemu-system-x86_64: ../../devel/qemu/accel/kvm/kvm-all.c:690: kvm_log_clear_one_slot: Assertion `QEMU_IS_ALIGNED(start | size, psize)' failed. >> Aborted (core dumped) > Hi Thomas, > > I think this patch is ok, maybe it trigger a potential bug? Well, sure, there is either a bug somewhere else or in this new code. But it's certainly not normal that the assert() triggers, is it? FWIW, here's a backtrace: #0 0x00007ffff2c1584f in raise () at /lib64/libc.so.6 #1 0x00007ffff2bffc45 in abort () at /lib64/libc.so.6 #2 0x00007ffff2bffb19 in _nl_load_domain.cold.0 () at /lib64/libc.so.6 #3 0x00007ffff2c0de36 in .annobin_assert.c_end () at /lib64/libc.so.6 #4 0x0000555555ba25f3 in kvm_log_clear_one_slot (size=6910080, start=0, as_id=0, mem=0x555556e1ee00) at ../../devel/qemu/accel/kvm/kvm-all.c:691 #5 0x0000555555ba25f3 in kvm_physical_log_clear (section=0x7fffffffd0b0, section=0x7fffffffd0b0, kml=0x555556dbaac0) at ../../devel/qemu/accel/kvm/kvm-all.c:843 #6 0x0000555555ba25f3 in kvm_log_clear (listener=0x555556dbaac0, section=0x7fffffffd0b0) at ../../devel/qemu/accel/kvm/kvm-all.c:1253 #7 0x0000555555b023d8 in memory_region_clear_dirty_bitmap (mr=mr@entry=0x5555573394c0, start=start@entry=0, len=len@entry=6910080) at ../../devel/qemu/softmmu/memory.c:2132 #8 0x0000555555b313d9 in cpu_physical_memory_snapshot_and_clear_dirty (mr=mr@entry=0x5555573394c0, offset=offset@entry=0, length=length@entry=6910080, client=client@entry=0) at ../../devel/qemu/softmmu/physmem.c:1109 #9 0x0000555555b02483 in memory_region_snapshot_and_clear_dirty (mr=mr@entry=0x5555573394c0, addr=addr@entry=0, size=size@entry=6910080, client=client@entry=0) at ../../devel/qemu/softmmu/memory.c:2146 #10 0x0000555555babe99 in vga_draw_graphic (full_update=0, s=0x5555573394b0) at ../../devel/qemu/hw/display/vga.c:1661 #11 0x0000555555babe99 in vga_update_display (opaque=0x5555573394b0) at ../../devel/qemu/hw/display/vga.c:1784 #12 0x0000555555babe99 in vga_update_display (opaque=0x5555573394b0) at ../../devel/qemu/hw/display/vga.c:1757 #13 0x00005555558ddd32 in graphic_hw_update (con=0x555556a11800) at ../../devel/qemu/ui/console.c:279 #14 0x00005555558dccd2 in dpy_refresh (s=0x555556c17da0) at ../../devel/qemu/ui/console.c:1742 #15 0x00005555558dccd2 in gui_update (opaque=opaque@entry=0x555556c17da0) at ../../devel/qemu/ui/console.c:209 #16 0x0000555555dbd520 in timerlist_run_timers (timer_list=0x555556937c50) at ../../devel/qemu/util/qemu-timer.c:574 #17 0x0000555555dbd520 in timerlist_run_timers (timer_list=0x555556937c50) at ../../devel/qemu/util/qemu-timer.c:499 #18 0x0000555555dbd74a in qemu_clock_run_timers (type=) at ../../devel/qemu/util/qemu-timer.c:670 #19 0x0000555555dbd74a in qemu_clock_run_all_timers () at ../../devel/qemu/util/qemu-timer.c:670 Looks like something in the vga code calls this with size=6910080 and thus triggers the alignment assertion? Thomas