KVM: Handle partial pae pdptr

Some guests (Solaris) do not set up all four pdptrs, but leave some invalid.
kvm incorrectly treated these as valid page directories, pinning the
wrong pages and causing general confusion.

Fix by checking the valid bit of a pae pdpte.  This closes sourceforge bug
1698922.

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

1 files changed, 12 insertions, 6 deletions

diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 8bdb9ca1811c..9ff74805c7d1 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -806,10 +806,12 @@ static void mmu_free_roots(struct kvm_vcpu *vcpu)
         for (i = 0; i < 4; ++i) {
                 hpa_t root = vcpu->mmu.pae_root[i];
 
-                ASSERT(VALID_PAGE(root));
-                root &= PT64_BASE_ADDR_MASK;
-                page = page_header(root);
-                --page->root_count;
+                if (root) {
+                        ASSERT(VALID_PAGE(root));
+                        root &= PT64_BASE_ADDR_MASK;
+                        page = page_header(root);
+                        --page->root_count;
+                }
                 vcpu->mmu.pae_root[i] = INVALID_PAGE;
         }
         vcpu->mmu.root_hpa = INVALID_PAGE;
@@ -840,9 +842,13 @@ static void mmu_alloc_roots(struct kvm_vcpu *vcpu)
                 hpa_t root = vcpu->mmu.pae_root[i];
 
                 ASSERT(!VALID_PAGE(root));
-                if (vcpu->mmu.root_level == PT32E_ROOT_LEVEL)
+                if (vcpu->mmu.root_level == PT32E_ROOT_LEVEL) {
+                        if (!is_present_pte(vcpu->pdptrs[i])) {
+                                vcpu->mmu.pae_root[i] = 0;
+                                continue;
+                        }
                         root_gfn = vcpu->pdptrs[i] >> PAGE_SHIFT;
-                else if (vcpu->mmu.root_level == 0)
+                } else if (vcpu->mmu.root_level == 0)
                         root_gfn = 0;
                 page = kvm_mmu_get_page(vcpu, root_gfn, i << 30,
                                         PT32_ROOT_LEVEL, !is_paging(vcpu),