[PATCH v2 4/4] KVM: x86/mmu: Store the address space ID in the TDP iterator

From: Ben Gardon <bgardon@google.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Sean Christopherson <seanjc@google.com>,
	Peter Shier <pshier@google.com>,
	Jim Mattson <jmattson@google.com>,
	Ben Gardon <bgardon@google.com>,
	kernel test robot <lkp@intel.com>
Subject: [PATCH v2 4/4] KVM: x86/mmu: Store the address space ID in the TDP iterator
Date: Mon, 15 Mar 2021 11:26:43 -0700	[thread overview]
Message-ID: <20210315182643.2437374-5-bgardon@google.com> (raw)
In-Reply-To: <20210315182643.2437374-1-bgardon@google.com>

Store the address space ID in the TDP iterator so that it can be
retrieved without having to bounce through the root shadow page.  This
streamlines the code and fixes a Sparse warning about not properly using
rcu_dereference() when grabbing the ID from the root on the fly.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
---
 arch/x86/kvm/mmu/mmu_internal.h |  5 +++++
 arch/x86/kvm/mmu/tdp_iter.c     |  6 +-----
 arch/x86/kvm/mmu/tdp_iter.h     |  3 ++-
 arch/x86/kvm/mmu/tdp_mmu.c      | 23 +++++------------------
 4 files changed, 13 insertions(+), 24 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index ec4fc28b325a..1f6f98c76bdf 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -78,6 +78,11 @@ static inline struct kvm_mmu_page *sptep_to_sp(u64 *sptep)
 	return to_shadow_page(__pa(sptep));
 }
 
+static inline int kvm_mmu_page_as_id(struct kvm_mmu_page *sp)
+{
+	return sp->role.smm ? 1 : 0;
+}
+
 static inline bool kvm_vcpu_ad_need_write_protect(struct kvm_vcpu *vcpu)
 {
 	/*
diff --git a/arch/x86/kvm/mmu/tdp_iter.c b/arch/x86/kvm/mmu/tdp_iter.c
index f7f94ea65243..b3ed302c1a35 100644
--- a/arch/x86/kvm/mmu/tdp_iter.c
+++ b/arch/x86/kvm/mmu/tdp_iter.c
@@ -49,6 +49,7 @@ void tdp_iter_start(struct tdp_iter *iter, u64 *root_pt, int root_level,
 	iter->root_level = root_level;
 	iter->min_level = min_level;
 	iter->pt_path[iter->root_level - 1] = (tdp_ptep_t)root_pt;
+	iter->as_id = kvm_mmu_page_as_id(sptep_to_sp(root_pt));
 
 	tdp_iter_restart(iter);
 }
@@ -169,8 +170,3 @@ void tdp_iter_next(struct tdp_iter *iter)
 	iter->valid = false;
 }
 
-tdp_ptep_t tdp_iter_root_pt(struct tdp_iter *iter)
-{
-	return iter->pt_path[iter->root_level - 1];
-}
-
diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h
index 8eb424d17c91..b1748b988d3a 100644
--- a/arch/x86/kvm/mmu/tdp_iter.h
+++ b/arch/x86/kvm/mmu/tdp_iter.h
@@ -36,6 +36,8 @@ struct tdp_iter {
 	int min_level;
 	/* The iterator's current level within the paging structure */
 	int level;
+	/* The address space ID, i.e. SMM vs. regular. */
+	int as_id;
 	/* A snapshot of the value at sptep */
 	u64 old_spte;
 	/*
@@ -62,7 +64,6 @@ tdp_ptep_t spte_to_child_pt(u64 pte, int level);
 void tdp_iter_start(struct tdp_iter *iter, u64 *root_pt, int root_level,
 		    int min_level, gfn_t next_last_level_gfn);
 void tdp_iter_next(struct tdp_iter *iter);
-tdp_ptep_t tdp_iter_root_pt(struct tdp_iter *iter);
 void tdp_iter_restart(struct tdp_iter *iter);
 
 #endif /* __KVM_X86_MMU_TDP_ITER_H */
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 38b6b6936171..462b1f71c77f 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -203,11 +203,6 @@ static void handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
 				u64 old_spte, u64 new_spte, int level,
 				bool shared);
 
-static int kvm_mmu_page_as_id(struct kvm_mmu_page *sp)
-{
-	return sp->role.smm ? 1 : 0;
-}
-
 static void handle_changed_spte_acc_track(u64 old_spte, u64 new_spte, int level)
 {
 	bool pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte);
@@ -497,10 +492,6 @@ static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm,
 					   struct tdp_iter *iter,
 					   u64 new_spte)
 {
-	u64 *root_pt = tdp_iter_root_pt(iter);
-	struct kvm_mmu_page *root = sptep_to_sp(root_pt);
-	int as_id = kvm_mmu_page_as_id(root);
-
 	lockdep_assert_held_read(&kvm->mmu_lock);
 
 	/*
@@ -514,8 +505,8 @@ static inline bool tdp_mmu_set_spte_atomic(struct kvm *kvm,
 		      new_spte) != iter->old_spte)
 		return false;
 
-	handle_changed_spte(kvm, as_id, iter->gfn, iter->old_spte, new_spte,
-			    iter->level, true);
+	handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte,
+			    new_spte, iter->level, true);
 
 	return true;
 }
@@ -569,10 +560,6 @@ static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter,
 				      u64 new_spte, bool record_acc_track,
 				      bool record_dirty_log)
 {
-	tdp_ptep_t root_pt = tdp_iter_root_pt(iter);
-	struct kvm_mmu_page *root = sptep_to_sp(root_pt);
-	int as_id = kvm_mmu_page_as_id(root);
-
 	lockdep_assert_held_write(&kvm->mmu_lock);
 
 	/*
@@ -586,13 +573,13 @@ static inline void __tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter,
 
 	WRITE_ONCE(*rcu_dereference(iter->sptep), new_spte);
 
-	__handle_changed_spte(kvm, as_id, iter->gfn, iter->old_spte, new_spte,
-			      iter->level, false);
+	__handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte,
+			      new_spte, iter->level, false);
 	if (record_acc_track)
 		handle_changed_spte_acc_track(iter->old_spte, new_spte,
 					      iter->level);
 	if (record_dirty_log)
-		handle_changed_spte_dirty_log(kvm, as_id, iter->gfn,
+		handle_changed_spte_dirty_log(kvm, iter->as_id, iter->gfn,
 					      iter->old_spte, new_spte,
 					      iter->level);
 }
-- 
2.31.0.rc2.261.g7f71774620-goog

