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Commit 2e2e3738 authored by Anthony Liguori's avatar Anthony Liguori Committed by Avi Kivity
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KVM: Handle vma regions with no backing page 



This patch allows VMAs that contain no backing page to be used for guest
memory.  This is useful for assigning mmio regions to a guest.

Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent d2ebb410

virt/kvm/kvm_main.c

+37 −12
Original line number Diff line number Diff line
@@ -532,6 +532,7 @@ pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn) 
	struct page *page[1];

	unsigned long addr;

	int npages;

	pfn_t pfn;



	might_sleep();
@@ -544,19 +545,38 @@ pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn) 
	npages = get_user_pages(current, current->mm, addr, 1, 1, 1, page,

				NULL);



	if (npages != 1) {

	if (unlikely(npages != 1)) {

		struct vm_area_struct *vma;



		vma = find_vma(current->mm, addr);

		if (vma == NULL || addr < vma->vm_start ||

		    !(vma->vm_flags & VM_PFNMAP)) {

			get_page(bad_page);

			return page_to_pfn(bad_page);

		}



	return page_to_pfn(page[0]);

		pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;

		BUG_ON(pfn_valid(pfn));

	} else

		pfn = page_to_pfn(page[0]);



	return pfn;

}



EXPORT_SYMBOL_GPL(gfn_to_pfn);



struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)

{

	return pfn_to_page(gfn_to_pfn(kvm, gfn));

	pfn_t pfn;



	pfn = gfn_to_pfn(kvm, gfn);

	if (pfn_valid(pfn))

		return pfn_to_page(pfn);



	WARN_ON(!pfn_valid(pfn));



	get_page(bad_page);

	return bad_page;

}



EXPORT_SYMBOL_GPL(gfn_to_page);
@@ -569,6 +589,7 @@ EXPORT_SYMBOL_GPL(kvm_release_page_clean); 


void kvm_release_pfn_clean(pfn_t pfn)

{

	if (pfn_valid(pfn))

		put_page(pfn_to_page(pfn));

}

EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
@@ -594,20 +615,24 @@ EXPORT_SYMBOL_GPL(kvm_set_page_dirty); 


void kvm_set_pfn_dirty(pfn_t pfn)

{

	if (pfn_valid(pfn)) {

		struct page *page = pfn_to_page(pfn);

		if (!PageReserved(page))

			SetPageDirty(page);

	}

}

EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);



void kvm_set_pfn_accessed(pfn_t pfn)

{

	if (pfn_valid(pfn))

		mark_page_accessed(pfn_to_page(pfn));

}

EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);



void kvm_get_pfn(pfn_t pfn)

{

	if (pfn_valid(pfn))

		get_page(pfn_to_page(pfn));

}

EXPORT_SYMBOL_GPL(kvm_get_pfn);