From 09e5f79b22aa19dd18bc63dd10f03f5ffddc2def Mon Sep 17 00:00:00 2001 From: Keir Fraser Date: Wed, 15 Dec 2010 10:31:59 +0000 Subject: [PATCH] x86/iommu: account for necessary allocations when calculating Dom0's initial allocation size As of c/s 21812:e382656e4dcc, IOMMU related allocations for Dom0 happen only after it got all of its memory allocated, and hence the reserve (mainly for setting up its swiotlb) may get exhausted without accounting for the necessary allocations up front. While not precise, the estimate has been found to be within a couple of pages for the systems it got tested on. For the calculation to be reasonably correct, this depends on the patch titled "x86/iommu: don't map RAM holes above 4G" sent out yesterday. Signed-off-by: Jan Beulich xen-unstable changeset: 22506:618ba64260fa xen-unstable date: Tue Dec 14 09:54:10 2010 +0000 --- xen/arch/x86/domain_build.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c index f9d1513f78..ec2c7a9970 100644 --- a/xen/arch/x86/domain_build.c +++ b/xen/arch/x86/domain_build.c @@ -188,6 +188,15 @@ static unsigned long __init compute_dom0_nr_pages( if ( is_pv_32on64_domain(d) ) avail -= opt_dom0_max_vcpus - 1; + /* Reserve memory for iommu_dom0_init() (rough estimate). */ + if ( iommu_enabled ) + { + unsigned int s; + + for ( s = 9; s < BITS_PER_LONG; s += 9 ) + avail -= max_page >> s; + } + /* * If domain 0 allocation isn't specified, reserve 1/16th of available * memory for things like DMA buffers. This reservation is clamped to