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xen: regression fixes for 4.0-rc6

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- Fix two regressions in the balloon driver's use of memory hotplug
   when used in a PV guest.
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Merge tag 'stable/for-linus-4.0-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip

Pull xen regression fixes from David Vrabel:
 "Fix two regressions in the balloon driver's use of memory hotplug when
  used in a PV guest"

* tag 'stable/for-linus-4.0-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/xen/tip:
  xen/balloon: before adding hotplugged memory, set frames to invalid
  x86/xen: prepare p2m list for memory hotplug
This commit is contained in:
Linus Torvalds 2015-04-02 13:53:53 -07:00
commit b0838b1501
3 changed files with 49 additions and 1 deletions
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10
arch/x86/xen/p2m.c
View File

@ -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);

17
drivers/xen/Kconfig
View File

@ -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

23
drivers/xen/balloon.c
View File

@ -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) {