From: Juergen Gross Date: Fri, 20 Mar 2015 12:55:39 +0000 (+0100) Subject: xen/balloon: before adding hotplugged memory, set frames to invalid X-Git-Tag: firefly_0821_release~176^2~2071^2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=3c56b3a12ce52f361468cbdd2f79b2f3b8da0ea6;p=firefly-linux-kernel-4.4.55.git xen/balloon: before adding 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 Signed-off-by: Juergen Gross Cc: # 3.16+ Reviewed-by: Daniel Kiper Signed-off-by: David Vrabel --- diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c index 0b52d92cb2e5..fd933695f232 100644 --- a/drivers/xen/balloon.c +++ b/drivers/xen/balloon.c @@ -229,6 +229,29 @@ 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 + /* + * add_memory() will build page tables for the new memory so + * the p2m must contain invalid entries so the correct + * non-present PTEs will be written. + * + * If a failure occurs, the original (identity) p2m entries + * are not restored since this region is now known not to + * conflict with any devices. + */ + 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) {