When PAE is in use, the root_hpa will not have a shadow page assoicated
with it. In this case the kernel will crash with a NULL pointer
dereference. Add checks to ensure is_tdp_mmu_root works as intended even
when using PAE.
Tested: compiles
Fixes: 02c00b3a2f7e ("kvm: x86/mmu: Allocate and free TDP MMU roots")
Reported-by: Zdenek Kaspar <zkaspar82@xxxxxxxxx>
Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
---
arch/x86/kvm/mmu/tdp_mmu.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 27e381c9da6c..13013f4d98ad 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -49,8 +49,18 @@ bool is_tdp_mmu_root(struct kvm *kvm, hpa_t hpa)
{
struct kvm_mmu_page *sp;
+ if (WARN_ON(!VALID_PAGE(hpa)))
+ return false;
+
sp = to_shadow_page(hpa);
+ /*
+ * If this VM is being run with PAE, the TDP MMU will not be enabled
+ * and the root HPA will not have a shadow page associated with it.
+ */
+ if (!sp)
+ return false;
+
return sp->tdp_mmu_page && sp->root_count;
}
--
2.29.2.222.g5d2a92d10f8-goog
