[PATCH] KVM: x86/tdp_mmu: Sprinkle __must_check

[Paolo Bonzini <pbonzini@xxxxxxxxxx>]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

The TDP MMU function __tdp_mmu_set_spte_atomic uses a cmpxchg64 to replace
the SPTE value and returns -EBUSY on failure.  The caller must check the
return value and retry.  Add __must_check to it, as well as to two more
functions that forward the return value of __tdp_mmu_set_spte_atomic to
their caller.

Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
Reviewed-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>
Message-Id: <8f7d5a1b241bf5351eaab828d1a1efe5c17699ca.1705965635.git.isaku.yamahata@xxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 36539c1b36cd..effb70f7dcba 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -530,7 +530,8 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
 		kvm_set_pfn_accessed(spte_to_pfn(old_spte));
 }
 
-static inline int __tdp_mmu_set_spte_atomic(struct tdp_iter *iter, u64 new_spte)
+static inline int __must_check __tdp_mmu_set_spte_atomic(struct tdp_iter *iter,
+							 u64 new_spte)
 {
 	u64 *sptep = rcu_dereference(iter->sptep);
 
@@ -572,9 +573,9 @@ static inline int __tdp_mmu_set_spte_atomic(struct tdp_iter *iter, u64 new_spte)
  *            no side-effects other than setting iter->old_spte to the last
  *            known value of the spte.
  */
-static inline int tdp_mmu_set_spte_atomic(struct kvm *kvm,
-					  struct tdp_iter *iter,
-					  u64 new_spte)
+static inline int __must_check tdp_mmu_set_spte_atomic(struct kvm *kvm,
+						       struct tdp_iter *iter,
+						       u64 new_spte)
 {
 	int ret;
 
@@ -590,8 +591,8 @@ static inline int tdp_mmu_set_spte_atomic(struct kvm *kvm,
 	return 0;
 }
 
-static inline int tdp_mmu_zap_spte_atomic(struct kvm *kvm,
-					  struct tdp_iter *iter)
+static inline int __must_check tdp_mmu_zap_spte_atomic(struct kvm *kvm,
+						       struct tdp_iter *iter)
 {
 	int ret;
 
-- 
2.43.0