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KVM: direct mmio pfn check

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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>
This commit is contained in:
Ben-Ami Yassour 2008-07-28 19:26:24 +03:00 committed by Avi Kivity
parent 0293615f3f
commit cbff90a7ca
1 changed files with 15 additions and 7 deletions
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22
virt/kvm/kvm_main.c
View file

@ -76,6 +76,14 @@ static inline int valid_vcpu(int n)
return likely(n >= 0 && n < KVM_MAX_VCPUS); 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() * Switches to specified vcpu, until a matching vcpu_put()
*/ */
@ -740,7 +748,7 @@ pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn)
} }
pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; pfn = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
BUG_ON(pfn_valid(pfn)); BUG_ON(!is_mmio_pfn(pfn));
} else } else
pfn = page_to_pfn(page[0]); pfn = page_to_pfn(page[0]);
@ -754,10 +762,10 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
pfn_t pfn; pfn_t pfn;
pfn = gfn_to_pfn(kvm, gfn); pfn = gfn_to_pfn(kvm, gfn);
if (pfn_valid(pfn)) if (!is_mmio_pfn(pfn))
return pfn_to_page(pfn); return pfn_to_page(pfn);
WARN_ON(!pfn_valid(pfn)); WARN_ON(is_mmio_pfn(pfn));
get_page(bad_page); get_page(bad_page);
return bad_page; return bad_page;
@ -773,7 +781,7 @@ EXPORT_SYMBOL_GPL(kvm_release_page_clean);
void kvm_release_pfn_clean(pfn_t pfn) void kvm_release_pfn_clean(pfn_t pfn)
{ {
if (pfn_valid(pfn)) if (!is_mmio_pfn(pfn))
put_page(pfn_to_page(pfn)); put_page(pfn_to_page(pfn));
} }
EXPORT_SYMBOL_GPL(kvm_release_pfn_clean); EXPORT_SYMBOL_GPL(kvm_release_pfn_clean);
@ -799,7 +807,7 @@ EXPORT_SYMBOL_GPL(kvm_set_page_dirty);
void kvm_set_pfn_dirty(pfn_t pfn) void kvm_set_pfn_dirty(pfn_t pfn)
{ {
if (pfn_valid(pfn)) { if (!is_mmio_pfn(pfn)) {
struct page *page = pfn_to_page(pfn); struct page *page = pfn_to_page(pfn);
if (!PageReserved(page)) if (!PageReserved(page))
SetPageDirty(page); SetPageDirty(page);
@ -809,14 +817,14 @@ EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty);
void kvm_set_pfn_accessed(pfn_t pfn) void kvm_set_pfn_accessed(pfn_t pfn)
{ {
if (pfn_valid(pfn)) if (!is_mmio_pfn(pfn))
mark_page_accessed(pfn_to_page(pfn)); mark_page_accessed(pfn_to_page(pfn));
} }
EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed); EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);
void kvm_get_pfn(pfn_t pfn) void kvm_get_pfn(pfn_t pfn)
{ {
if (pfn_valid(pfn)) if (!is_mmio_pfn(pfn))
get_page(pfn_to_page(pfn)); get_page(pfn_to_page(pfn));
} }
EXPORT_SYMBOL_GPL(kvm_get_pfn); EXPORT_SYMBOL_GPL(kvm_get_pfn);