From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: Re: [PATCH] xl, e820_host, PV passthrough: Fix guests crashing when memory == maxmem Date: Fri, 24 May 2013 10:51:31 -0400 Message-ID: <20130524145131.GG4404@phenom.dumpdata.com> References: <1369402576-2958-1-git-send-email-konrad.wilk@oracle.com> <1369403904.17830.201.camel@zakaz.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <1369403904.17830.201.camel@zakaz.uk.xensource.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell , george.dunlap@eu.citrix.com Cc: Konrad Rzeszutek Wilk , xen-devel@lists.xensource.com, david.vrabel@citrix.com, christian@holpert.de List-Id: xen-devel@lists.xenproject.org On Fri, May 24, 2013 at 02:58:24PM +0100, Ian Campbell wrote: > On Fri, 2013-05-24 at 09:36 -0400, Konrad Rzeszutek Wilk wrote: > > The code had an obvious bug where it would assume that the balloon > > amount would always be _something_ and add an E820_RAM entry at the > > end of the E820 array. The added E820_RAM would contain the balloon amount > > plus the delta of memory that had to be subtracted b/c of the various > > E820 entries. That assumption is certainly true when maxmem != mem, > > but if guest config has maxmem = memory that is incorrect (as balloon > > value is zero). The end result is that the E820 that is constructed > > is missing a swath of "delta" memory and in most cases ends up with > > only one E820_RAM entry that is of 512MB size on many Intel systems. > > > > Reported-by: Christian Holpert > > Signed-off-by: Konrad Rzeszutek Wilk > > Acked-by: Ian Campbell George, Would you be OK putting this in Xen 4.3? It is only exposed if a user 1) launches a PV guest 2). Has in the guest config: pci=['blabla']\ne820_host=1 3). Is not that freq used as only a couple of people seem to use it > > > --- > > tools/libxl/libxl_x86.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/tools/libxl/libxl_x86.c b/tools/libxl/libxl_x86.c > > index a17f6ae..a78c91d 100644 > > --- a/tools/libxl/libxl_x86.c > > +++ b/tools/libxl/libxl_x86.c > > @@ -182,7 +182,7 @@ static int e820_sanitize(libxl_ctx *ctx, struct e820entry src[], > > idx++; > > } > > /* At this point we have the mapped RAM + E820 entries from src. */ > > - if (balloon_kb) { > > + if (balloon_kb || delta_kb) { > > /* and if we truncated the RAM region, then add it to the end. */ > > e820[idx].type = E820_RAM; > > e820[idx].addr = (uint64_t)(1ULL << 32) > last ? > >