[PATCH 09/50] KVM: Handle vma regions with no backing page
- From: Avi Kivity <avi@xxxxxxxxxxxx>
- Date: Thu, 26 Jun 2008 15:27:51 +0300
From: Anthony Liguori <aliguori@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxxxx>
---
virt/kvm/kvm_main.c | 49 +++++++++++++++++++++++++++++++++++++------------
1 files changed, 37 insertions(+), 12 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 764d702..4d30ac5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -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);
--
1.5.6
--
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- References:
- [PATCH 00/50] KVM patches review for the 2.6.27 merge window
- From: Avi Kivity
- [PATCH 00/50] KVM patches review for the 2.6.27 merge window
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