KVM: x86: handle invalid root_hpa everywhere

Rom Freiman <rom@stratoscale.com> notes other code paths vulnerable to
bug fixed by 989c6b34f6a9480e397b.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

2 files changed, 17 insertions, 0 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 31a570287fcc..e50425d0f5f7 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2832,6 +2832,9 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
         bool ret = false;
         u64 spte = 0ull;
 
+        if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+                return false;
+
         if (!page_fault_can_be_fast(error_code))
                 return false;
 
@@ -3227,6 +3230,9 @@ static u64 walk_shadow_page_get_mmio_spte(struct kvm_vcpu *vcpu, u64 addr)
         struct kvm_shadow_walk_iterator iterator;
         u64 spte = 0ull;
 
+        if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+                return spte;
+
         walk_shadow_page_lockless_begin(vcpu);
         for_each_shadow_entry_lockless(vcpu, addr, iterator, spte)
                 if (!is_shadow_present_pte(spte))
@@ -4513,6 +4519,9 @@ int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4])
         u64 spte;
         int nr_sptes = 0;
 
+        if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+                return nr_sptes;
+
         walk_shadow_page_lockless_begin(vcpu);
         for_each_shadow_entry_lockless(vcpu, addr, iterator, spte) {
                 sptes[iterator.level-1] = spte;
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index ad75d77999d0..cba218a2f08d 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -569,6 +569,9 @@ static int FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
         if (FNAME(gpte_changed)(vcpu, gw, top_level))
                 goto out_gpte_changed;
 
+        if (!VALID_PAGE(vcpu->arch.mmu.root_hpa))
+                goto out_gpte_changed;
+
         for (shadow_walk_init(&it, vcpu, addr);
              shadow_walk_okay(&it) && it.level > gw->level;
              shadow_walk_next(&it)) {
@@ -820,6 +823,11 @@ static void FNAME(invlpg)(struct kvm_vcpu *vcpu, gva_t gva)
          */
         mmu_topup_memory_caches(vcpu);
 
+        if (!VALID_PAGE(vcpu->arch.mmu.root_hpa)) {
+                WARN_ON(1);
+                return;
+        }
+
         spin_lock(&vcpu->kvm->mmu_lock);
         for_each_shadow_entry(vcpu, gva, iterator) {
                 level = iterator.level;