From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:58040) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1e4261-0000X1-KG for qemu-devel@nongnu.org; Mon, 16 Oct 2017 05:54:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1e425y-0005Zm-8J for qemu-devel@nongnu.org; Mon, 16 Oct 2017 05:54:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:59894) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1e425y-0005ZY-21 for qemu-devel@nongnu.org; Mon, 16 Oct 2017 05:54:02 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id DA36BC04AC48 for ; Mon, 16 Oct 2017 09:54:00 +0000 (UTC) References: <20171016094121.16455-1-david@redhat.com> From: David Hildenbrand Message-ID: <650c557c-4c1c-181e-75b5-bcb58ddb2746@redhat.com> Date: Mon, 16 Oct 2017 11:53:59 +0200 MIME-Version: 1.0 In-Reply-To: <20171016094121.16455-1-david@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v1] kvm: tolerate non-existing slot for log_start and log_stop List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: thuth@redhat.com, Paolo Bonzini On 16.10.2017 11:41, David Hildenbrand wrote: > log_start might be called by memory.c just before registering the > section. So we can actually get a log_start without a region_add, which > we can silently ignore. > > This makes current KVM code trigger an assertion > ("kvm_section_update_flags: error finding slot"). > > Also, if we want to trap every access to a section, we might not have a > slot. So let's just tolerate if we don't have a slot. > > Fixes: 343562e8fa22 ("kvm: kvm_log_start/stop are only called with known sections") > Reported-by: Thomas Huth > Signed-off-by: David Hildenbrand > --- > accel/kvm/kvm-all.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > index 90c88b517d..64de8461e0 100644 > --- a/accel/kvm/kvm-all.c > +++ b/accel/kvm/kvm-all.c > @@ -394,8 +394,11 @@ static int kvm_section_update_flags(KVMMemoryListener *kml, > > mem = kvm_lookup_matching_slot(kml, start_addr, size); > if (!mem) { > - fprintf(stderr, "%s: error finding slot\n", __func__); > - abort(); > + /* > + * log_start() might be called before region_add(), and sometimes > + * we don't have a slot as we want to trap every access. > + */ > + return 0; > } > > return kvm_slot_update_flags(kml, mem, section->mr); > I'll also send a patch for log_sync(), dropping the same assert. Looks like adding these assertions was counter productive :) -- Thanks, David