[PATCH] KVM: x86/mmu: Properly dereference rcu-protected TDP MMU sptep iterator

[Sean Christopherson <seanjc@xxxxxxxxxx>]

Wrap the read of iter->sptep in tdp_mmu_map_handle_target_level() with
rcu_dereference().  Shadow pages in the TDP MMU, and thus their SPTEs,
are protected by rcu.

This fixes a Sparse warning at tdp_mmu.c:900:51:
  warning: incorrect type in argument 1 (different address spaces)
  expected unsigned long long [usertype] *sptep
  got unsigned long long [noderef] [usertype] __rcu *[usertype] sptep

Fixes: 7158bee4b475 ("KVM: MMU: pass kvm_mmu_page struct to make_spte")
Cc: Ben Gardon <bgardon@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 7c5dd83e52de..a54c3491af42 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -897,7 +897,7 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
 					  struct kvm_page_fault *fault,
 					  struct tdp_iter *iter)
 {
-	struct kvm_mmu_page *sp = sptep_to_sp(iter->sptep);
+	struct kvm_mmu_page *sp = sptep_to_sp(rcu_dereference(iter->sptep));
 	u64 new_spte;
 	int ret = RET_PF_FIXED;
 	bool wrprot = false;
-- 
2.33.1.1089.g2158813163f-goog