linux-kernel - [PATCH 5/5] KVM: x86/mmu: Move kvm_tdp_mmu_map()'s prolog and epilog to its caller

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Date:   Tue, 13 Dec 2022 03:30:30 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Robert Hoo <robert.hu@...ux.intel.com>,
        Greg Thelen <gthelen@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Ben Gardon <bgardon@...gle.com>,
        Mingwei Zhang <mizhang@...gle.com>
Subject: [PATCH 5/5] KVM: x86/mmu: Move kvm_tdp_mmu_map()'s prolog and epilog
 to its caller

Move the hugepage adjust, tracepoint, and RCU (un)lock logic out of
kvm_tdp_mmu_map() and into its sole caller, kvm_tdp_mmu_page_fault(), to
eliminate the gotos used to bounce through rcu_read_unlock() when bailing
from the walk.

Opportunistically mark kvm_mmu_hugepage_adjust() as static as
kvm_tdp_mmu_map() was the only external user.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu/mmu.c          |  9 ++++++++-
 arch/x86/kvm/mmu/mmu_internal.h |  1 -
 arch/x86/kvm/mmu/tdp_mmu.c      | 22 ++++------------------
 3 files changed, 12 insertions(+), 20 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 254bc46234e0..99c40617d325 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3085,7 +3085,8 @@ int kvm_mmu_max_mapping_level(struct kvm *kvm,
 	return min(host_level, max_level);
 }
 
-void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
+static void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu,
+				    struct kvm_page_fault *fault)
 {
 	struct kvm_memory_slot *slot = fault->slot;
 	kvm_pfn_t mask;
@@ -4405,7 +4406,13 @@ static int kvm_tdp_mmu_page_fault(struct kvm_vcpu *vcpu,
 	if (is_page_fault_stale(vcpu, fault))
 		goto out_unlock;
 
+	kvm_mmu_hugepage_adjust(vcpu, fault);
+
+	trace_kvm_mmu_spte_requested(fault);
+
+	rcu_read_lock();
 	r = kvm_tdp_mmu_map(vcpu, fault);
+	rcu_read_unlock();
 
 out_unlock:
 	read_unlock(&vcpu->kvm->mmu_lock);
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index ac00bfbf32f6..66c294d67641 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -317,7 +317,6 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
 int kvm_mmu_max_mapping_level(struct kvm *kvm,
 			      const struct kvm_memory_slot *slot, gfn_t gfn,
 			      int max_level);
-void kvm_mmu_hugepage_adjust(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
 void disallowed_hugepage_adjust(struct kvm_page_fault *fault, u64 spte, int cur_level);
 
 void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index cc1fb9a65620..78f47eb74544 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -1150,13 +1150,6 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	struct kvm *kvm = vcpu->kvm;
 	struct tdp_iter iter;
 	struct kvm_mmu_page *sp;
-	int ret = RET_PF_RETRY;
-
-	kvm_mmu_hugepage_adjust(vcpu, fault);
-
-	trace_kvm_mmu_spte_requested(fault);
-
-	rcu_read_lock();
 
 	tdp_mmu_for_each_pte(iter, mmu, fault->gfn, fault->gfn + 1) {
 		int r;
@@ -1169,10 +1162,10 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 		 * retry, avoiding unnecessary page table allocation and free.
 		 */
 		if (is_removed_spte(iter.old_spte))
-			goto retry;
+			return RET_PF_RETRY;
 
 		if (iter.level == fault->goal_level)
-			goto map_target_level;
+			return tdp_mmu_map_handle_target_level(vcpu, fault, &iter);
 
 		/* Step down into the lower level page table if it exists. */
 		if (is_shadow_present_pte(iter.old_spte) &&
@@ -1199,7 +1192,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 		 */
 		if (r) {
 			tdp_mmu_free_sp(sp);
-			goto retry;
+			return RET_PF_RETRY;
 		}
 
 		if (fault->huge_page_disallowed &&
@@ -1216,14 +1209,7 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 	 * iterator detected an upper level SPTE was frozen during traversal.
 	 */
 	WARN_ON_ONCE(iter.level == fault->goal_level);
-	goto retry;
-
-map_target_level:
-	ret = tdp_mmu_map_handle_target_level(vcpu, fault, &iter);
-
-retry:
-	rcu_read_unlock();
-	return ret;
+	return RET_PF_RETRY;
 }
 
 bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range,
-- 
2.39.0.rc1.256.g54fd8350bd-goog