Re: [PATCH V3 4/8] xen: Delay invalidating extra memory

[Juergen Gross]

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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