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authorIan Campbell <Ian.Campbell@citrix.com>2011-12-14 12:16:08 +0000
committerGreg Kroah-Hartman <gregkh@suse.de>2011-12-21 12:57:42 -0800
commit37e8c2c97ab911f99cb75c0b5596150a34e06023 (patch)
treef4fd3be237f7b80019b76fe495c1a394aaa2500f
parentd8091fda7895ed0624d1641089f4080164e75a35 (diff)
xen: only limit memory map to maximum reservation for domain 0.
commit d3db728125c4470a2d061ac10fa7395e18237263 upstream. d312ae878b6a "xen: use maximum reservation to limit amount of usable RAM" clamped the total amount of RAM to the current maximum reservation. This is correct for dom0 but is not correct for guest domains. In order to boot a guest "pre-ballooned" (e.g. with memory=1G but maxmem=2G) in order to allow for future memory expansion the guest must derive max_pfn from the e820 provided by the toolstack and not the current maximum reservation (which can reflect only the current maximum, not the guest lifetime max). The existing algorithm already behaves this correctly if we do not artificially limit the maximum number of pages for the guest case. For a guest booted with maxmem=512, memory=128 this results in: [ 0.000000] BIOS-provided physical RAM map: [ 0.000000] Xen: 0000000000000000 - 00000000000a0000 (usable) [ 0.000000] Xen: 00000000000a0000 - 0000000000100000 (reserved) -[ 0.000000] Xen: 0000000000100000 - 0000000008100000 (usable) -[ 0.000000] Xen: 0000000008100000 - 0000000020800000 (unusable) +[ 0.000000] Xen: 0000000000100000 - 0000000020800000 (usable) ... [ 0.000000] NX (Execute Disable) protection: active [ 0.000000] DMI not present or invalid. [ 0.000000] e820 update range: 0000000000000000 - 0000000000010000 (usable) ==> (reserved) [ 0.000000] e820 remove range: 00000000000a0000 - 0000000000100000 (usable) -[ 0.000000] last_pfn = 0x8100 max_arch_pfn = 0x1000000 +[ 0.000000] last_pfn = 0x20800 max_arch_pfn = 0x1000000 [ 0.000000] initial memory mapped : 0 - 027ff000 [ 0.000000] Base memory trampoline at [c009f000] 9f000 size 4096 -[ 0.000000] init_memory_mapping: 0000000000000000-0000000008100000 -[ 0.000000] 0000000000 - 0008100000 page 4k -[ 0.000000] kernel direct mapping tables up to 8100000 @ 27bb000-27ff000 +[ 0.000000] init_memory_mapping: 0000000000000000-0000000020800000 +[ 0.000000] 0000000000 - 0020800000 page 4k +[ 0.000000] kernel direct mapping tables up to 20800000 @ 26f8000-27ff000 [ 0.000000] xen: setting RW the range 27e8000 - 27ff000 [ 0.000000] 0MB HIGHMEM available. -[ 0.000000] 129MB LOWMEM available. -[ 0.000000] mapped low ram: 0 - 08100000 -[ 0.000000] low ram: 0 - 08100000 +[ 0.000000] 520MB LOWMEM available. +[ 0.000000] mapped low ram: 0 - 20800000 +[ 0.000000] low ram: 0 - 20800000 With this change "xl mem-set <domain> 512M" will successfully increase the guest RAM (by reducing the balloon). There is no change for dom0. Reported-and-Tested-by: George Shuklin <george.shuklin@gmail.com> Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Reviewed-by: David Vrabel <david.vrabel@citrix.com> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--arch/x86/xen/setup.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index acea42ee4eed..f8dcda493146 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -192,9 +192,21 @@ static unsigned long __init xen_get_max_pages(void)
domid_t domid = DOMID_SELF;
int ret;
- ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
- if (ret > 0)
- max_pages = ret;
+ /*
+ * For the initial domain we use the maximum reservation as
+ * the maximum page.
+ *
+ * For guest domains the current maximum reservation reflects
+ * the current maximum rather than the static maximum. In this
+ * case the e820 map provided to us will cover the static
+ * maximum region.
+ */
+ if (xen_initial_domain()) {
+ ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
+ if (ret > 0)
+ max_pages = ret;
+ }
+
return min(max_pages, MAX_DOMAIN_PAGES);
}