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spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:42632 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lJeTO-0004sw-Nr for qemu-devel@archiver.kernel.org; Tue, 09 Mar 2021 10:40:38 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:50238) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lJdoL-0005R7-Mg for qemu-devel@nongnu.org; Tue, 09 Mar 2021 09:58:15 -0500 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:50172) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1lJdoH-0002lP-DO for qemu-devel@nongnu.org; Tue, 09 Mar 2021 09:58:13 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615301887; 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=rAQA3tcvp0tq3g1EHejBPjwgLMcXkHYaMzRqzot0XC4=; b=hzTXG4tu0W1gJpwFGGFYsArC9CUAAR+1a5zf+R2bihi8lTLhN1XSHMs/n6JObd6D51hEVo fgi7tKn+f0a6ssJsoQiIpEb0jZXKs7u7VacdXGYQqBvYIOk5WboDMjkYfYwvzSN5LmDb7J w7KGHSm4BwkNf9CASD6uu34+9KOpTUQ= 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-501-FnZ1EWRkM0irL7hFlHwJrw-1; Tue, 09 Mar 2021 09:58:06 -0500 X-MC-Unique: FnZ1EWRkM0irL7hFlHwJrw-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 87E2E108BD08; Tue, 9 Mar 2021 14:58:04 +0000 (UTC) Received: from work-vm (ovpn-112-63.ams2.redhat.com [10.36.112.63]) by smtp.corp.redhat.com (Postfix) with ESMTPS id A7D3B5C233; Tue, 9 Mar 2021 14:57:55 +0000 (UTC) Date: Tue, 9 Mar 2021 14:57:53 +0000 From: "Dr. David Alan Gilbert" To: Thomas Huth Subject: Re: [PATCH v2 2/2] accel: kvm: Add aligment assert for kvm_log_clear_one_slot Message-ID: 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> <11854ebf-ed88-496d-8381-5385ef1b403a@redhat.com> MIME-Version: 1.0 In-Reply-To: <11854ebf-ed88-496d-8381-5385ef1b403a@redhat.com> User-Agent: Mutt/2.0.5 (2021-01-21) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Received-SPF: pass client-ip=216.205.24.124; envelope-from=dgilbert@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, 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 , Andrew Jones , jiangkunkun@huawei.com, qemu-devel@nongnu.org, Peter Xu , qemu-arm@nongnu.org, Gerd Hoffmann , wanghaibin.wang@huawei.com, Zenghui Yu , Paolo Bonzini , Keqian Zhu Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Thomas Huth (thuth@redhat.com) wrote: > 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 Could you please figure out which memory region this is? WTH is that size? Is that really the problem that the size is just crazy? Dave > #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 -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK