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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: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
This commit is contained in:
Anthony Liguori 2008-04-30 15:37:07 -05:00 committed by Avi Kivity
parent d2ebb4103f
commit 2e2e3738af
1 changed files with 37 additions and 12 deletions
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49
virt/kvm/kvm_main.c
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@ -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) {
get_page(bad_page);
return page_to_pfn(bad_page);
}
if (unlikely(npages != 1)) {
struct vm_area_struct *vma;
return page_to_pfn(page[0]);
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);
}
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);
@ -569,7 +589,8 @@ EXPORT_SYMBOL_GPL(kvm_release_page_clean);
void kvm_release_pfn_clean(pfn_t pfn)
{
put_page(pfn_to_page(pfn));
if (pfn_valid(pfn))
put_page(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
@ -594,21 +615,25 @@ EXPORT_SYMBOL_GPL(kvm_set_page_dirty);
void kvm_set_pfn_dirty(pfn_t pfn)
{
struct page *page = pfn_to_page(pfn);
if (!PageReserved(page))
SetPageDirty(page);
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)
{
mark_page_accessed(pfn_to_page(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)
{
get_page(pfn_to_page(pfn));
if (pfn_valid(pfn))
get_page(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_get_pfn);