From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56825) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c6ae9-0001jy-IH for qemu-devel@nongnu.org; Tue, 15 Nov 2016 05:07:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c6ae6-0002f2-Au for qemu-devel@nongnu.org; Tue, 15 Nov 2016 05:07:21 -0500 Received: from mx1.redhat.com ([209.132.183.28]:39998) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1c6ae6-0002eu-3L for qemu-devel@nongnu.org; Tue, 15 Nov 2016 05:07:18 -0500 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (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 37AEDC05678C for ; Tue, 15 Nov 2016 10:07:17 +0000 (UTC) From: Juan Quintela In-Reply-To: <20161115095403.GD2038@work-vm> (David Alan Gilbert's message of "Tue, 15 Nov 2016 09:54:03 +0000") References: <1479156950-2517-1-git-send-email-quintela@redhat.com> <1479156950-2517-3-git-send-email-quintela@redhat.com> <20161115095403.GD2038@work-vm> Reply-To: quintela@redhat.com Date: Tue, 15 Nov 2016 11:07:13 +0100 Message-ID: <87shqtcazy.fsf@emacs.mitica> MIME-Version: 1.0 Content-Type: text/plain 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: "Dr. David Alan Gilbert" Cc: qemu-devel@nongnu.org, amit.shah@redhat.com "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? 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