Re: [PATCH 1/2] xen: prepare p2m list for memory hotplug

Juergen Gross
2015-03-19T17:01:28Z

On 03/19/2015 04:53 PM, Boris Ostrovsky wrote:
> On 03/19/2015 10:31 AM, Juergen Gross wrote:
>> 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 <jgross@suse.com>
>> ---
>> arch/x86/xen/p2m.c | 13 ++++++++++++-
>> drivers/xen/Kconfig | 13 +++++++++++++
>> 2 files changed, 25 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
>> index 9f93af5..30e84ae 100644
>> --- a/arch/x86/xen/p2m.c
>> +++ b/arch/x86/xen/p2m.c
>> @@ -91,6 +91,17 @@ 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
>> +#ifdef CONFIG_X86_32
>> +BUILD_BUG_ON_MSG(CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT > 64)
>
> Will this work in Kconfig instead?
>
> range 0 64 if CONFIG_X86_32

I'll give it a try.

Juergen

>
> -boris
>
>> +#endif
>> +#define P2M_LIMIT max(xen_max_p2m_pfn, \
>> + ((unsigned long)((u64)CONFIG_XEN_BALLOON_MEMORY_HOTPLUG_LIMIT * \
>> + 1024 * 1024 * 1024 / PAGE_SIZE)))
>> +#else
>> +#define P2M_LIMIT xen_max_p2m_pfn
>> +#endif
>> +
>> static DEFINE_SPINLOCK(p2m_update_lock);
>> static unsigned long *p2m_mid_missing_mfn;
>> @@ -387,7 +398,7 @@ void __init xen_vmalloc_p2m_tree(void)
>> static struct vm_struct vm;
>> vm.flags = VM_ALLOC;
>> - vm.size = ALIGN(sizeof(unsigned long) * xen_max_p2m_pfn,
>> + vm.size = ALIGN(sizeof(unsigned long) * 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 b812462..0a61ddf 100644
>> --- a/drivers/xen/Kconfig
>> +++ b/drivers/xen/Kconfig
>> @@ -55,6 +55,19 @@ config XEN_BALLOON_MEMORY_HOTPLUG
>> In that case step 3 should be omitted.
>> +config XEN_BALLOON_MEMORY_HOTPLUG_LIMIT
>> + int
>> + default 512 if X86_64
>> + default 4 if X86_32
>> + depends on XEN_HAVE_PVMMU
>> + depends on XEN_BALLOON_MEMORY_HOTPLUG
>> + help
>> + Upper limit in GBs a pv domain can be expanded to using memory
>> + hotplug.
>> +
>> + 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
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at http://www.tux.org/lkml/
>
>