From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35884) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dB2HE-0001Cl-09 for qemu-devel@nongnu.org; Wed, 17 May 2017 12:58:20 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dB2HC-0000F2-0U for qemu-devel@nongnu.org; Wed, 17 May 2017 12:58:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:37674) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dB2HB-0000El-Q6 for qemu-devel@nongnu.org; Wed, 17 May 2017 12:58:17 -0400 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 mx1.redhat.com (Postfix) with ESMTPS id 94B5C369C4 for ; Wed, 17 May 2017 16:58:16 +0000 (UTC) From: "Dr. David Alan Gilbert (git)" Date: Wed, 17 May 2017 17:58:09 +0100 Message-Id: <20170517165810.18164-2-dgilbert@redhat.com> In-Reply-To: <20170517165810.18164-1-dgilbert@redhat.com> References: <20170517165810.18164-1-dgilbert@redhat.com> Subject: [Qemu-devel] [PATCH 1/2] migration: Fix non-multiple of page size migration List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, quintela@redhat.com, peterx@redhat.com, lvivier@redhat.com From: "Dr. David Alan Gilbert" Unfortunately it's legal to create a VM with a RAM size that's not a multiple of the underlying host page or huge page size. Recently I'd changed things to always send host sized pages, and that breaks if we have say a 1025MB guest on 2MB hugepages. Unfortunately we can't just make that illegal since it would break migration from/to existing oddly configured VMs. Symptom: qemu-system-x86_64: Illegal RAM offset 40100000 as it transmits the fraction of the hugepage after the end of the RAMBlock (may also cause a crash on the source - possibly due to clearing bits after the bitmap) Reported-by: Yumei Huang Red Hat bug: https://bugzilla.redhat.com/show_bug.cgi?id=1449037 Signed-off-by: Dr. David Alan Gilbert --- migration/ram.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/migration/ram.c b/migration/ram.c index 293d27ce83..cea8924c02 100644 --- a/migration/ram.c +++ b/migration/ram.c @@ -1305,6 +1305,8 @@ static int ram_save_target_page(RAMState *rs, PageSearchStatus *pss, * a host page in which case the remainder of the hostpage is sent. * Only dirty target pages are sent. Note that the host page size may * be a huge page for this block. + * The saving stops at the boundary of the used_length of the block + * if the RAMBlock isn't a multiple of the host page size. * * Returns the number of pages written or negative on error * @@ -1328,7 +1330,8 @@ static int ram_save_host_page(RAMState *rs, PageSearchStatus *pss, pages += tmppages; pss->page++; - } while (pss->page & (pagesize_bits - 1)); + } while ((pss->page & (pagesize_bits - 1)) && + offset_in_ramblock(pss->block, pss->page << TARGET_PAGE_BITS)); /* The offset we leave with is the last one we looked at */ pss->page--; -- 2.13.0