linux-kernel - [Patch V2 2/2] xen: before ballooning hotplugged memory, set frames to invalid

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Date:	Fri, 20 Mar 2015 13:55:39 +0100
From:	Juergen Gross <jgross@...e.com>
To:	linux-kernel@...r.kernel.org, xen-devel@...ts.xensource.com,
	konrad.wilk@...cle.com, david.vrabel@...rix.com,
	boris.ostrovsky@...cle.com, daniel.kiper@...cle.com,
	pebolle@...cali.nl
Cc:	Juergen Gross <jgross@...e.com>
Subject: [Patch V2 2/2] xen: before ballooning hotplugged memory, set frames to invalid

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@...rix.com>
Signed-off-by: Juergen Gross <jgross@...e.com>
---
 drivers/xen/balloon.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index 0b52d92..65fedb8 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -229,6 +229,19 @@ static enum bp_state reserve_additional_memory(long credit)
 	balloon_hotplug = round_up(balloon_hotplug, PAGES_PER_SECTION);
 	nid = memory_add_physaddr_to_nid(hotplug_start_paddr);
 
+#ifdef CONFIG_XEN_HAVE_PVMMU
+	if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+		unsigned long pfn, i;
+
+		pfn = PFN_DOWN(hotplug_start_paddr);
+		for (i = 0; i < balloon_hotplug; i++)
+			if (!set_phys_to_machine(pfn + i, INVALID_P2M_ENTRY)) {
+				pr_warn("set_phys_to_machine() failed, no memory added\n");
+				return BP_ECANCELED;
+			}
+	}
+#endif
+
 	rc = add_memory(nid, hotplug_start_paddr, balloon_hotplug << PAGE_SHIFT);
 
 	if (rc) {
-- 
2.1.4

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