linux-kernel - [RFC PATCH v5 046/104] KVM: x86/tdp_mmu: refactor kvm_tdp_mmu

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Message-Id: <8ac26dfbe645aa3e9a9f39c844dfec9c0ac841ec.1646422845.git.isaku.yamahata@intel.com>
Date:   Fri,  4 Mar 2022 11:49:02 -0800
From:   isaku.yamahata@...el.com
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: [RFC PATCH v5 046/104] KVM: x86/tdp_mmu: refactor kvm_tdp_mmu_map()

From: Isaku Yamahata <isaku.yamahata@...el.com>

Factor out non-leaf SPTE population logic from kvm_tdp_mmu_map().  MapGPA
hypercall needs to populate non-leaf SPTE to record which GPA, private or
shared, is allowed in the leaf EPT entry.

Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 arch/x86/kvm/mmu/tdp_mmu.c | 48 ++++++++++++++++++++++++--------------
 1 file changed, 30 insertions(+), 18 deletions(-)

diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index b6ec2f112c26..8db262440d5c 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -955,6 +955,31 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
 	return ret;
 }
 
+static bool tdp_mmu_populate_nonleaf(
+	struct kvm_vcpu *vcpu, struct tdp_iter *iter, bool account_nx)
+{
+	struct kvm_mmu_page *sp;
+	u64 *child_pt;
+	u64 new_spte;
+
+	WARN_ON(is_shadow_present_pte(iter->old_spte));
+	WARN_ON(is_removed_spte(iter->old_spte));
+
+	sp = alloc_tdp_mmu_page(vcpu, iter->gfn, iter->level - 1);
+	child_pt = sp->spt;
+
+	new_spte = make_nonleaf_spte(child_pt, !shadow_accessed_mask);
+
+	if (!tdp_mmu_set_spte_atomic(vcpu->kvm, iter, new_spte)) {
+		tdp_mmu_free_sp(sp);
+		return false;
+	}
+
+	tdp_mmu_link_page(vcpu->kvm, sp, account_nx);
+	trace_kvm_mmu_get_page(sp, true);
+	return true;
+}
+
 /*
  * Handle a TDP page fault (NPT/EPT violation/misconfiguration) by installing
  * page tables and SPTEs to translate the faulting guest physical address.
@@ -963,9 +988,6 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 {
 	struct kvm_mmu *mmu = vcpu->arch.mmu;
 	struct tdp_iter iter;
-	struct kvm_mmu_page *sp;
-	u64 *child_pt;
-	u64 new_spte;
 	int ret;
 
 	kvm_mmu_hugepage_adjust(vcpu, fault);
@@ -1000,6 +1022,8 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 		}
 
 		if (!is_shadow_present_pte(iter.old_spte)) {
+			bool account_nx;
+
 			/*
 			 * If SPTE has been frozen by another thread, just
 			 * give up and retry, avoiding unnecessary page table
@@ -1008,22 +1032,10 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
 			if (is_removed_spte(iter.old_spte))
 				break;
 
-			sp = alloc_tdp_mmu_page(vcpu, iter.gfn, iter.level - 1);
-			child_pt = sp->spt;
-
-			new_spte = make_nonleaf_spte(child_pt,
-						     !shadow_accessed_mask);
-
-			if (tdp_mmu_set_spte_atomic(vcpu->kvm, &iter, new_spte)) {
-				tdp_mmu_link_page(vcpu->kvm, sp,
-						  fault->huge_page_disallowed &&
-						  fault->req_level >= iter.level);
-
-				trace_kvm_mmu_get_page(sp, true);
-			} else {
-				tdp_mmu_free_sp(sp);
+			account_nx = fault->huge_page_disallowed &&
+				fault->req_level >= iter.level;
+			if (!tdp_mmu_populate_nonleaf(vcpu, &iter, account_nx))
 				break;
-			}
 		}
 	}
 
-- 
2.25.1