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xen p2m: transparently change the p2m mappings in the m2p override
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> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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@ -407,8 +407,11 @@ static unsigned long mfn_hash(unsigned long mfn)
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void m2p_add_override(unsigned long mfn, struct page *page)
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void m2p_add_override(unsigned long mfn, struct page *page)
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{
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{
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unsigned long flags;
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unsigned long flags;
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unsigned long pfn = page_to_pfn(page);
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page->private = mfn;
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page->private = mfn;
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page->index = pfn_to_mfn(pfn);
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__set_phys_to_machine(pfn, FOREIGN_FRAME(mfn));
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spin_lock_irqsave(&m2p_override_lock, flags);
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spin_lock_irqsave(&m2p_override_lock, flags);
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list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
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list_add(&page->lru, &m2p_overrides[mfn_hash(mfn)]);
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spin_unlock_irqrestore(&m2p_override_lock, flags);
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spin_unlock_irqrestore(&m2p_override_lock, flags);
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@ -417,9 +420,18 @@ void m2p_add_override(unsigned long mfn, struct page *page)
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void m2p_remove_override(struct page *page)
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void m2p_remove_override(struct page *page)
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{
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{
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unsigned long flags;
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unsigned long flags;
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unsigned long mfn;
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unsigned long pfn;
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pfn = page_to_pfn(page);
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mfn = get_phys_to_machine(pfn);
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if (mfn == INVALID_P2M_ENTRY || !(mfn & FOREIGN_FRAME_BIT))
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return;
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spin_lock_irqsave(&m2p_override_lock, flags);
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spin_lock_irqsave(&m2p_override_lock, flags);
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list_del(&page->lru);
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list_del(&page->lru);
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spin_unlock_irqrestore(&m2p_override_lock, flags);
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spin_unlock_irqrestore(&m2p_override_lock, flags);
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__set_phys_to_machine(pfn, page->index);
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}
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}
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struct page *m2p_find_override(unsigned long mfn)
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struct page *m2p_find_override(unsigned long mfn)
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