Messages in this thread | | | Date | Wed, 15 Dec 2010 15:36:34 -0800 | From | Jeremy Fitzhardinge <> | Subject | Re: [Xen-devel] [PATCH 08/11] xen p2m: transparently change the p2m mappings in the m2p override |
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On 12/15/2010 05:40 AM, stefano.stabellini@eu.citrix.com wrote: > From: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > > In m2p_add_override store the original mfn into page->index and then > change the p2m mapping, setting mfns as FOREIGN_FRAME. > > In m2p_remove_override restore the original mapping. > > Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> > --- > arch/x86/xen/p2m.c | 4 ++++ > 1 files changed, 4 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c > index 8db19d5..7dde8e4 100644 > --- a/arch/x86/xen/p2m.c > +++ b/arch/x86/xen/p2m.c > @@ -407,8 +407,11 @@ static unsigned long mfn_hash(unsigned long mfn) > void m2p_add_override(unsigned long mfn, struct page *page) > { > unsigned long flags; > + unsigned long pfn = page_to_pfn(page); > page->private = mfn; > + page->index = pfn_to_mfn(pfn);
Is there any risk that a page being used for a granted mfn will end up getting xen_create_contiguous_region() applied to it via the DMA API? That would be messy...
J
> > + __set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)); > spin_lock_irqsave(&m2p_override_lock, flags); > list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]); > spin_unlock_irqrestore(&m2p_override_lock, flags); > @@ -420,6 +423,7 @@ void m2p_remove_override(struct page *page) > spin_lock_irqsave(&m2p_override_lock, flags); > list_del(&page->lru); > spin_unlock_irqrestore(&m2p_override_lock, flags); > + __set_phys_to_machine(page_to_pfn(page), page->index); > } > > struct page *m2p_find_override(unsigned long mfn)
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