linux-kernel - [PATCH v4 2/9] KVM: MMU: stop dereferencing vcpu->arch.mmu to get the context for MMU init

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Date:   Fri, 10 Jul 2020 16:11:50 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 2/9] KVM: MMU: stop dereferencing vcpu->arch.mmu to get the context for MMU init

From: Paolo Bonzini <pbonzini@...hat.com>

kvm_init_shadow_mmu() was actually the only function that could be called
with different vcpu->arch.mmu values.  Now that kvm_init_shadow_npt_mmu()
is separated from kvm_init_shadow_mmu(), we always know the MMU context
we need to use and there is no need to dereference vcpu->arch.mmu pointer.

Based on a patch by Vitaly Kuznetsov <vkuznets@...hat.com>.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/mmu/mmu.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 93f18e5fa8b5..3a306ab1a9c9 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4884,7 +4884,7 @@ kvm_calc_tdp_mmu_root_page_role(struct kvm_vcpu *vcpu, bool base_only)
 
 static void init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
 {
-	struct kvm_mmu *context = vcpu->arch.mmu;
+	struct kvm_mmu *context = &vcpu->arch.root_mmu;
 	union kvm_mmu_role new_role =
 		kvm_calc_tdp_mmu_root_page_role(vcpu, false);
 
@@ -4952,11 +4952,10 @@ kvm_calc_shadow_mmu_root_page_role(struct kvm_vcpu *vcpu, bool base_only)
 	return role;
 }
 
-static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4,
-				    u32 efer, union kvm_mmu_role new_role)
+static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, struct kvm_mmu *context,
+				    u32 cr0, u32 cr4, u32 efer,
+				    union kvm_mmu_role new_role)
 {
-	struct kvm_mmu *context = vcpu->arch.mmu;
-
 	if (!(cr0 & X86_CR0_PG))
 		nonpaging_init_context(vcpu, context);
 	else if (efer & EFER_LMA)
@@ -4972,23 +4971,23 @@ static void shadow_mmu_init_context(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4,
 
 static void kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4, u32 efer)
 {
-	struct kvm_mmu *context = vcpu->arch.mmu;
+	struct kvm_mmu *context = &vcpu->arch.root_mmu;
 	union kvm_mmu_role new_role =
 		kvm_calc_shadow_mmu_root_page_role(vcpu, false);
 
 	if (new_role.as_u64 != context->mmu_role.as_u64)
-		shadow_mmu_init_context(vcpu, cr0, cr4, efer, new_role);
+		shadow_mmu_init_context(vcpu, context, cr0, cr4, efer, new_role);
 }
 
 void kvm_init_shadow_npt_mmu(struct kvm_vcpu *vcpu, u32 cr0, u32 cr4, u32 efer,
 			     gpa_t nested_cr3)
 {
-	struct kvm_mmu *context = vcpu->arch.mmu;
+	struct kvm_mmu *context = &vcpu->arch.guest_mmu;
 	union kvm_mmu_role new_role =
 		kvm_calc_shadow_mmu_root_page_role(vcpu, false);
 
 	if (new_role.as_u64 != context->mmu_role.as_u64)
-		shadow_mmu_init_context(vcpu, cr0, cr4, efer, new_role);
+		shadow_mmu_init_context(vcpu, context, cr0, cr4, efer, new_role);
 }
 EXPORT_SYMBOL_GPL(kvm_init_shadow_npt_mmu);
 
@@ -5024,7 +5023,7 @@ kvm_calc_shadow_ept_root_page_role(struct kvm_vcpu *vcpu, bool accessed_dirty,
 void kvm_init_shadow_ept_mmu(struct kvm_vcpu *vcpu, bool execonly,
 			     bool accessed_dirty, gpa_t new_eptp)
 {
-	struct kvm_mmu *context = vcpu->arch.mmu;
+	struct kvm_mmu *context = &vcpu->arch.guest_mmu;
 	u8 level = vmx_eptp_page_walk_level(new_eptp);
 	union kvm_mmu_role new_role =
 		kvm_calc_shadow_ept_root_page_role(vcpu, accessed_dirty,
@@ -5058,7 +5057,7 @@ EXPORT_SYMBOL_GPL(kvm_init_shadow_ept_mmu);
 
 static void init_kvm_softmmu(struct kvm_vcpu *vcpu)
 {
-	struct kvm_mmu *context = vcpu->arch.mmu;
+	struct kvm_mmu *context = &vcpu->arch.root_mmu;
 
 	kvm_init_shadow_mmu(vcpu,
 			    kvm_read_cr0_bits(vcpu, X86_CR0_PG),
-- 
2.25.4