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Commit 633d6f17 authored by Juergen Gross's avatar Juergen Gross Committed by David Vrabel
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x86/xen: prepare p2m list for memory hotplug 



Commit 054954eb ("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: default avatarJuergen Gross <jgross@suse.com>
Cc: <stable@vger.kernel.org> # 3.19+
Reviewed-by: default avatarDaniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
parent af6fc858

arch/x86/xen/p2m.c

+9 −1
Original line number Diff line number Diff line
@@ -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);

drivers/xen/Kconfig

+17 −0
Original line number Diff line number Diff line
@@ -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