KVM: direct mmio pfn check
Userspace may specify memory slots that are backed by mmio pages rather than
normal RAM. In some cases it is not enough to identify these mmio pages
by pfn_valid(). This patch adds checking the PageReserved as well.
Signed-off-by: Ben-Ami Yassour <benami@il.ibm.com>
Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7dd9b0b..5eb96c7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -76,6 +76,14 @@
return likely(n >= 0 && n < KVM_MAX_VCPUS);
}
+static inline int is_mmio_pfn(pfn_t pfn)
+{
+ if (pfn_valid(pfn))
+ return PageReserved(pfn_to_page(pfn));
+
+ return true;
+}
+
/*
* Switches to specified vcpu, until a matching vcpu_put()
*/
@@ -740,7 +748,7 @@
}
pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
- BUG_ON(pfn_valid(pfn));
+ BUG_ON(!is_mmio_pfn(pfn));
} else
pfn = page_to_pfn(page[0]);
@@ -754,10 +762,10 @@
pfn_t pfn;
pfn = gfn_to_pfn(kvm, gfn);
- if (pfn_valid(pfn))
+ if (!is_mmio_pfn(pfn))
return pfn_to_page(pfn);
- WARN_ON(!pfn_valid(pfn));
+ WARN_ON(is_mmio_pfn(pfn));
get_page(bad_page);
return bad_page;
@@ -773,7 +781,7 @@
void kvm_release_pfn_clean(pfn_t pfn)
{
- if (pfn_valid(pfn))
+ if (!is_mmio_pfn(pfn))
put_page(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
@@ -799,7 +807,7 @@
void kvm_set_pfn_dirty(pfn_t pfn)
{
- if (pfn_valid(pfn)) {
+ if (!is_mmio_pfn(pfn)) {
struct page *page = pfn_to_page(pfn);
if (!PageReserved(page))
SetPageDirty(page);
@@ -809,14 +817,14 @@
void kvm_set_pfn_accessed(pfn_t pfn)
{
- if (pfn_valid(pfn))
+ if (!is_mmio_pfn(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))
+ if (!is_mmio_pfn(pfn))
get_page(pfn_to_page(pfn));
}
EXPORT_SYMBOL_GPL(kvm_get_pfn);