linux-kernel - [PATCH 43/43] KVM: x86: Drop pointless @reset_roots from kvm_init

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Date:   Fri, 23 Apr 2021 17:46:45 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 43/43] KVM: x86: Drop pointless @reset_roots from kvm_init_mmu()

Remove the @reset_roots param from kvm_init_mmu(), the one user,
kvm_mmu_reset_context() has already unloaded the MMU and thus freed and
invalidated all roots.  This also happens to be why the reset_roots=true
paths doesn't leak roots; they're already invalid.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu.h        |  2 +-
 arch/x86/kvm/mmu/mmu.c    | 13 ++-----------
 arch/x86/kvm/svm/nested.c |  2 +-
 arch/x86/kvm/vmx/nested.c |  2 +-
 4 files changed, 5 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/mmu.h b/arch/x86/kvm/mmu.h
index 88d0ed5225a4..63b49725fb24 100644
--- a/arch/x86/kvm/mmu.h
+++ b/arch/x86/kvm/mmu.h
@@ -65,7 +65,7 @@ void kvm_mmu_set_ept_masks(bool has_ad_bits, bool has_exec_only);
 void
 reset_shadow_zero_bits_mask(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
 
-void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots);
+void kvm_init_mmu(struct kvm_vcpu *vcpu);
 void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4, u32 efer,
 			     gpa_t nested_cr3);
 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 930ac8a7e7c9..ff3e200b32dd 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4793,17 +4793,8 @@ static void init_kvm_nested_mmu(struct kvm_vcpu *vcpu)
 	update_last_nonleaf_level(vcpu, g_context);
 }
 
-void kvm_init_mmu(struct kvm_vcpu *vcpu, bool reset_roots)
+void kvm_init_mmu(struct kvm_vcpu *vcpu)
 {
-	if (reset_roots) {
-		uint i;
-
-		vcpu->arch.mmu->root_hpa = INVALID_PAGE;
-
-		for (i = 0; i < KVM_MMU_NUM_PREV_ROOTS; i++)
-			vcpu->arch.mmu->prev_roots[i] = KVM_MMU_ROOT_INFO_INVALID;
-	}
-
 	if (mmu_is_nested(vcpu))
 		init_kvm_nested_mmu(vcpu);
 	else if (tdp_enabled)
@@ -4829,7 +4820,7 @@ kvm_mmu_calc_root_page_role(struct kvm_vcpu *vcpu)
 void kvm_mmu_reset_context(struct kvm_vcpu *vcpu)
 {
 	kvm_mmu_unload(vcpu);
-	kvm_init_mmu(vcpu, true);
+	kvm_init_mmu(vcpu);
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_reset_context);
 
diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
index 540d43ba2cf4..a0b48a8f32ed 100644
--- a/arch/x86/kvm/svm/nested.c
+++ b/arch/x86/kvm/svm/nested.c
@@ -406,7 +406,7 @@ static int nested_svm_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3,
 	vcpu->arch.cr3 = cr3;
 	kvm_register_mark_available(vcpu, VCPU_EXREG_CR3);
 
-	kvm_init_mmu(vcpu, false);
+	kvm_init_mmu(vcpu);
 
 	return 0;
 }
diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index 9dcdf158a405..3a5b86932a5e 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -1137,7 +1137,7 @@ static int nested_vmx_load_cr3(struct kvm_vcpu *vcpu, unsigned long cr3, bool ne
 	vcpu->arch.cr3 = cr3;
 	kvm_register_mark_available(vcpu, VCPU_EXREG_CR3);
 
-	kvm_init_mmu(vcpu, false);
+	kvm_init_mmu(vcpu);
 
 	return 0;
 }
-- 
2.31.1.498.g6c1eba8ee3d-goog