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SubjectRe: [PATCH V3 4/8] xen: Delay invalidating extra memory
On 11/12/2014 11:10 PM, Konrad Rzeszutek Wilk wrote:
>> @@ -376,12 +374,14 @@ void __init xen_build_dynamic_phys_to_machine(void)
>> unsigned long max_pfn;
>> unsigned long pfn;
>>
>> - if (xen_feature(XENFEAT_auto_translated_physmap))
>> + if (xen_feature(XENFEAT_auto_translated_physmap))
>
> Spurious change.

I'll remove it.

>
> .. snip..
>> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
>> index 0e5f9b6..8d5985b 100644
>> --- a/arch/x86/xen/setup.c
>> +++ b/arch/x86/xen/setup.c
>> @@ -75,7 +75,6 @@ static unsigned long xen_remap_mfn __initdata = INVALID_P2M_ENTRY;
>>
>> static void __init xen_add_extra_mem(u64 start, u64 size)
>> {
>> - unsigned long pfn;
>> int i;
>>
>> for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
>> @@ -95,17 +94,74 @@ static void __init xen_add_extra_mem(u64 start, u64 size)
>> printk(KERN_WARNING "Warning: not enough extra memory regions\n");
>>
>> memblock_reserve(start, size);
>> +}
>>
>> - xen_max_p2m_pfn = PFN_DOWN(start + size);
>> - for (pfn = PFN_DOWN(start); pfn < xen_max_p2m_pfn; pfn++) {
>> - unsigned long mfn = pfn_to_mfn(pfn);
>> +static void __init xen_del_extra_mem(u64 start, u64 size)
>> +{
>> + int i;
>> + u64 start_r, size_r;
>>
>> - if (WARN_ONCE(mfn == pfn, "Trying to over-write 1-1 mapping (pfn: %lx)\n", pfn))
>> - continue;
>> - WARN_ONCE(mfn != INVALID_P2M_ENTRY, "Trying to remove %lx which has %lx mfn!\n",
>> - pfn, mfn);
>> + for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
>> + start_r = xen_extra_mem[i].start;
>> + size_r = xen_extra_mem[i].size;
>> +
>> + /* Start of region. */
>> + if (start_r == start) {
>> + BUG_ON(size > size_r);
>> + xen_extra_mem[i].start += size;
>> + xen_extra_mem[i].size -= size;
>> + break;
>> + }
>> + /* End of region. */
>> + if (start_r + size_r == start + size) {
>> + BUG_ON(size > size_r);
>> + xen_extra_mem[i].size -= size;
>> + break;
>> + }
>> + /* Mid of region. */
>> + if (start > start_r && start < start_r + size_r) {
>> + BUG_ON(start + size > start_r + size_r);
>> + xen_extra_mem[i].size = start - start_r;
>> + xen_add_extra_mem(start + size, start_r + size_r -
>> + (start + size));
>
> Which ends up calling 'memblock_reserve' for an region it already has
> reserved. Should we call memblock_free(start_r, size_r - size) before calling this?
>
> Or is that not neccessary as memblock_* is pretty smart about this sort of thing?

Regions marked via memblock_reserve() are allowed to overlap. I can add
a comment.


Juergen



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