From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36914) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c6bBs-0004Q0-Ma for qemu-devel@nongnu.org; Tue, 15 Nov 2016 05:42:13 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c6bBo-0007DP-LR for qemu-devel@nongnu.org; Tue, 15 Nov 2016 05:42:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:58512) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c6bBo-0007DD-DT for qemu-devel@nongnu.org; Tue, 15 Nov 2016 05:42:08 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 768D56196F for ; Tue, 15 Nov 2016 10:42:07 +0000 (UTC) Date: Tue, 15 Nov 2016 10:42:03 +0000 From: "Dr. David Alan Gilbert" Message-ID: <20161115104203.GF2038@work-vm> References: <1479156950-2517-1-git-send-email-quintela@redhat.com> <1479156950-2517-3-git-send-email-quintela@redhat.com> <20161115095403.GD2038@work-vm> <87shqtcazy.fsf@emacs.mitica> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87shqtcazy.fsf@emacs.mitica> Subject: Re: [Qemu-devel] [PATCH 2/3] migration: Test for disabled features on reception List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Juan Quintela Cc: qemu-devel@nongnu.org, amit.shah@redhat.com * Juan Quintela (quintela@redhat.com) wrote: > "Dr. David Alan Gilbert" wrote: > > * Juan Quintela (quintela@redhat.com) wrote: > >> Right now, if we receive a compressed page or a xbzrle page while this > >> features are disabled, Bad Things (TM) can happen. Just add a test for > >> them. > > > > This confuses me; I didn't think until recently we could > > guarantee anything about having the capabilities set on the destination > > side. Until -incoming defer the destination didn't have a way of setting > > capabilities in a known state before starting the reception. > > Ouch. > > So, here we are after further investigation. > > - xbzrle: we don't need anything special on the reception side, we just > decode inplace. So we are good. If we don't use xbzrle, we > don't waste any resources either. > - compression: We create the decompression threads always, with all its > associated configuration. > > > Why do I wanted to do this? For multifd, I don't really want to create > multiple fd's except if configured, because I wait for the fd's to be > "accepted" before continue, so I need a way to know if it is configured > or no. So I need something like this. > > I started doing this for compression because when I was debugging I had > too many threads waiting on qemu_cond_wait(), and I only wanted to look > at the multifd ones. > > I had not througth that we didn't need to set capabilities on > destination. > > Suggestions? It's fine for new features to require it; newer libvirt already does it for postcopy and does: -incoming defer sets the capabilities and parameters migrate_incoming URI However, enforcing it for old features sounds something we can't do. Dave > Later, Juan. > > > > > Dave > > > >> Signed-off-by: Juan Quintela > >> --- > >> migration/ram.c | 23 ++++++++++++++++++++++- > >> 1 file changed, 22 insertions(+), 1 deletion(-) > >> > >> diff --git a/migration/ram.c b/migration/ram.c > >> index fb9252d..4bb707c 100644 > >> --- a/migration/ram.c > >> +++ b/migration/ram.c > >> @@ -2464,7 +2464,7 @@ static int ram_load_postcopy(QEMUFile *f) > >> > >> static int ram_load(QEMUFile *f, void *opaque, int version_id) > >> { > >> - int flags = 0, ret = 0; > >> + int flags = 0, ret = 0, invalid_flags; > >> static uint64_t seq_iter; > >> int len = 0; > >> /* > >> @@ -2479,6 +2479,15 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) > >> ret = -EINVAL; > >> } > >> > >> + invalid_flags = 0; > >> + > >> + if (!migrate_use_xbzrle()) { > >> + invalid_flags |= RAM_SAVE_FLAG_XBZRLE; > >> + } > >> + > >> + if (!migrate_use_compression()) { > >> + invalid_flags |= RAM_SAVE_FLAG_COMPRESS_PAGE; > >> + } > >> /* This RCU critical section can be very long running. > >> * When RCU reclaims in the code start to become numerous, > >> * it will be necessary to reduce the granularity of this > >> @@ -2499,6 +2508,18 @@ static int ram_load(QEMUFile *f, void *opaque, int version_id) > >> flags = addr & ~TARGET_PAGE_MASK; > >> addr &= TARGET_PAGE_MASK; > >> > >> + if (flags & invalid_flags) { > >> + if (flags & invalid_flags & RAM_SAVE_FLAG_XBZRLE) { > >> + error_report("Received an unexpected XBRLE page"); > >> + } > >> + if (flags & invalid_flags & RAM_SAVE_FLAG_COMPRESS_PAGE) { > >> + error_report("Received an unexpected compressed page"); > >> + } > >> + > >> + ret = -EINVAL; > >> + break; > >> + } > >> + > >> if (flags & (RAM_SAVE_FLAG_COMPRESS | RAM_SAVE_FLAG_PAGE | > >> RAM_SAVE_FLAG_COMPRESS_PAGE | RAM_SAVE_FLAG_XBZRLE)) { > >> RAMBlock *block = ram_block_from_stream(f, flags); > >> -- > >> 2.7.4 > >> > > -- > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK