KVM: MMU: Introduce gfn_to_gpa()

Converting a frame number to an address is tricky since the data type changes
size.  Introduce a function to do it.  This fixes an actual bug when
accessing guest ptes.

Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index 048849d97b3587db825cfcfa95093a730714066a..eda82cded88e6dca4b0310d2719f790c6c5223a1 100644 (file)
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -499,6 +499,10 @@ static inline int memslot_id(struct kvm *kvm, struct kvm_memory_slot *slot)
        return slot - kvm->memslots;
 }
 
+static inline gpa_t gfn_to_gpa(gfn_t gfn)
+{
+       return (gpa_t)gfn << PAGE_SHIFT;
+}
 
 enum kvm_stat_kind {
        KVM_STAT_VM,

diff --git a/drivers/kvm/paging_tmpl.h b/drivers/kvm/paging_tmpl.h
index a3da98bfd6a62561dea5b5217fd2b3ff2da95094..b24bc7c86078423b6ec821355b12493c408de93b 100644 (file)
--- a/drivers/kvm/paging_tmpl.h
+++ b/drivers/kvm/paging_tmpl.h
@@ -110,7 +110,7 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
                index = PT_INDEX(addr, walker->level);
 
                table_gfn = gpte_to_gfn(pte);
-               pte_gpa = table_gfn << PAGE_SHIFT;
+               pte_gpa = gfn_to_gpa(table_gfn);
                pte_gpa += index * sizeof(pt_element_t);
                walker->table_gfn[walker->level - 1] = table_gfn;
                pgprintk("%s: table_gfn[%d] %lx\n", __FUNCTION__,
@@ -442,7 +442,7 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr)
        r = FNAME(walk_addr)(&walker, vcpu, vaddr, 0, 0, 0);
 
        if (r) {
-               gpa = (gpa_t)walker.gfn << PAGE_SHIFT;
+               gpa = gfn_to_gpa(walker.gfn);
                gpa |= vaddr & ~PAGE_MASK;
        }