[PATCH 2/2] xen: before ballooning hotplugged memory, set frames to invalid

Juergen Gross
2015-03-19T14:31:40Z

Commit 25b884a83d487fd62c3de7ac1ab5549979188482 ("x86/xen: set
regions above the end of RAM as 1:1") introduced a regression.

To be able to add memory pages which were added via memory hotplug to
a pv domain, the pages must be "invalid" instead of "identity" in the
p2m list before they can be added.

Suggested-by: David Vrabel <david.vrabel@citrix.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
drivers/xen/balloon.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 0b52d92..52e331f 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -221,15 +221,24 @@ static bool balloon_is_inflated(void)

static enum bp_state reserve_additional_memory(long credit)
{
- int nid, rc;
+ int nid, rc = 0;
u64 hotplug_start_paddr;
unsigned long balloon_hotplug = credit;
+ unsigned long pfn;

hotplug_start_paddr = PFN_PHYS(SECTION_ALIGN_UP(max_pfn));
balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
nid = memory_add_physaddr_to_nid(hotplug_start_paddr);

- rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug << PAGE_SHIFT);
+ for (pfn = PFN_DOWN(hotplug_start_paddr);
+ !rc && pfn < PFN_DOWN(hotplug_start_paddr) + balloon_hotplug;
+ pfn++)
+ if (!set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
+ rc = 1;
+
+ if (!rc)
+ rc = add_memory(nid, hotplug_start_paddr,
+ balloon_hotplug << PAGE_SHIFT);

if (rc) {
pr_warn("Cannot add additional memory (%i)\n", rc);
--
2.1.4