From 633d6f17cd91ad5bf2370265946f716e42d388c6 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Fri, 20 Mar 2015 13:55:38 +0100 Subject: [PATCH 1/2] x86/xen: prepare p2m list for memory hotplug Commit 054954eb051f35e74b75a566a96fe756015352c8 ("xen: switch to linear virtual mapped sparse p2m list") introduced a regression regarding to memory hotplug for a pv-domain: as the virtual space for the p2m list is allocated for the to be expected memory size of the domain only, hotplugged memory above that size will not be usable by the domain. Correct this by using a configurable size for the p2m list in case of memory hotplug enabled (default supported memory size is 512 GB for 64 bit domains and 4 GB for 32 bit domains). Signed-off-by: Juergen Gross Cc: # 3.19+ Reviewed-by: Daniel Kiper Signed-off-by: David Vrabel --- arch/x86/xen/p2m.c | 10 +++++++++- drivers/xen/Kconfig | 17 +++++++++++++++++ 2 files changed, 26 insertions(+), 1 deletion(-) diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 9f93af56a5fc..b47124d4cd67 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -91,6 +91,12 @@ EXPORT_SYMBOL_GPL(xen_p2m_size); unsigned long xen_max_p2m_pfn __read_mostly; EXPORT_SYMBOL_GPL(xen_max_p2m_pfn); +#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT +#define P2M_LIMIT CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT +#else +#define P2M_LIMIT 0 +#endif + static DEFINE_SPINLOCK(p2m_update_lock); static unsigned long *p2m_mid_missing_mfn; @@ -385,9 +391,11 @@ static void __init xen_rebuild_p2m_list(unsigned long *p2m) void __init xen_vmalloc_p2m_tree(void) { static struct vm_struct vm; + unsigned long p2m_limit; + p2m_limit = (phys_addr_t)P2M_LIMIT * 1024 * 1024 * 1024 / PAGE_SIZE; vm.flags = VM_ALLOC; - vm.size = ALIGN(sizeof(unsigned long) * xen_max_p2m_pfn, + vm.size = ALIGN(sizeof(unsigned long) * max(xen_max_p2m_pfn, p2m_limit), PMD_SIZE * PMDS_PER_MID_PAGE); vm_area_register_early(&vm, PMD_SIZE * PMDS_PER_MID_PAGE); pr_notice("p2m virtual area at %p, size is %lx\n", vm.addr, vm.size); diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig index b812462083fc..94d96809e686 100644 --- a/drivers/xen/Kconfig +++ b/drivers/xen/Kconfig @@ -55,6 +55,23 @@ config XEN_BALLOON_MEMORY_HOTPLUG In that case step 3 should be omitted. +config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT + int "Hotplugged memory limit (in GiB) for a PV guest" + default 512 if X86_64 + default 4 if X86_32 + range 0 64 if X86_32 + depends on XEN_HAVE_PVMMU + depends on XEN_BALLOON_MEMORY_HOTPLUG + help + Maxmium amount of memory (in GiB) that a PV guest can be + expanded to when using memory hotplug. + + A PV guest can have more memory than this limit if is + started with a larger maximum. + + This value is used to allocate enough space in internal + tables needed for physical memory administration. + config XEN_SCRUB_PAGES bool "Scrub pages before returning them to system" depends on XEN_BALLOON From 3c56b3a12ce52f361468cbdd2f79b2f3b8da0ea6 Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Fri, 20 Mar 2015 13:55:39 +0100 Subject: [PATCH 2/2] 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 --- drivers/xen/balloon.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) 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) {