KVM: MMU: Introduce kvm_init_shadow_mmu helper function

Some logic of the init_kvm_softmmu function is required to
build the Nested Nested Paging context. So factor the
required logic into a seperate function and export it.
Also make the whole init path suitable for more than one mmu
context.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/kvm/mmu.c

@@ -2532,10 +2532,9 @@ static void nonpaging_free(struct kvm_vcpu *vcpu)
 	mmu_free_roots(vcpu);
 }
 
-static int nonpaging_init_context(struct kvm_vcpu *vcpu)
+static int nonpaging_init_context(struct kvm_vcpu *vcpu,
+				  struct kvm_mmu *context)
 {
-	struct kvm_mmu *context = &vcpu->arch.mmu;
-
 	context->new_cr3 = nonpaging_new_cr3;
 	context->page_fault = nonpaging_page_fault;
 	context->gva_to_gpa = nonpaging_gva_to_gpa;
@@ -2595,9 +2594,10 @@ static bool is_rsvd_bits_set(struct kvm_vcpu *vcpu, u64 gpte, int level)
 #include "paging_tmpl.h"
 #undef PTTYPE
 
-static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu, int level)
+static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu,
+				  struct kvm_mmu *context,
+				  int level)
 {
-	struct kvm_mmu *context = &vcpu->arch.mmu;
 	int maxphyaddr = cpuid_maxphyaddr(vcpu);
 	u64 exb_bit_rsvd = 0;
 
@@ -2656,9 +2656,11 @@ static void reset_rsvds_bits_mask(struct kvm_vcpu *vcpu, int level)
 	}
 }
 
-static int paging64_init_context_common(struct kvm_vcpu *vcpu, int level)
+static int paging64_init_context_common(struct kvm_vcpu *vcpu,
+					struct kvm_mmu *context,
+					int level)
 {
-	struct kvm_mmu *context = &vcpu->arch.mmu;
+	reset_rsvds_bits_mask(vcpu, context, level);
 
 	ASSERT(is_pae(vcpu));
 	context->new_cr3 = paging_new_cr3;
@@ -2675,17 +2677,17 @@ static int paging64_init_context_common(struct kvm_vcpu *vcpu, int level)
 	return 0;
 }
 
-static int paging64_init_context(struct kvm_vcpu *vcpu)
+static int paging64_init_context(struct kvm_vcpu *vcpu,
+				 struct kvm_mmu *context)
 {
-	reset_rsvds_bits_mask(vcpu, PT64_ROOT_LEVEL);
-	return paging64_init_context_common(vcpu, PT64_ROOT_LEVEL);
+	return paging64_init_context_common(vcpu, context, PT64_ROOT_LEVEL);
 }
 
-static int paging32_init_context(struct kvm_vcpu *vcpu)
+static int paging32_init_context(struct kvm_vcpu *vcpu,
+				 struct kvm_mmu *context)
 {
-	struct kvm_mmu *context = &vcpu->arch.mmu;
+	reset_rsvds_bits_mask(vcpu, context, PT32_ROOT_LEVEL);
 
-	reset_rsvds_bits_mask(vcpu, PT32_ROOT_LEVEL);
 	context->new_cr3 = paging_new_cr3;
 	context->page_fault = paging32_page_fault;
 	context->gva_to_gpa = paging32_gva_to_gpa;
@@ -2700,10 +2702,10 @@ static int paging32_init_context(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
-static int paging32E_init_context(struct kvm_vcpu *vcpu)
+static int paging32E_init_context(struct kvm_vcpu *vcpu,
+				  struct kvm_mmu *context)
 {
-	reset_rsvds_bits_mask(vcpu, PT32E_ROOT_LEVEL);
-	return paging64_init_context_common(vcpu, PT32E_ROOT_LEVEL);
+	return paging64_init_context_common(vcpu, context, PT32E_ROOT_LEVEL);
 }
 
 static int init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
@@ -2727,15 +2729,15 @@ static int init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
 		context->gva_to_gpa = nonpaging_gva_to_gpa;
 		context->root_level = 0;
 	} else if (is_long_mode(vcpu)) {
-		reset_rsvds_bits_mask(vcpu, PT64_ROOT_LEVEL);
+		reset_rsvds_bits_mask(vcpu, context, PT64_ROOT_LEVEL);
 		context->gva_to_gpa = paging64_gva_to_gpa;
 		context->root_level = PT64_ROOT_LEVEL;
 	} else if (is_pae(vcpu)) {
-		reset_rsvds_bits_mask(vcpu, PT32E_ROOT_LEVEL);
+		reset_rsvds_bits_mask(vcpu, context, PT32E_ROOT_LEVEL);
 		context->gva_to_gpa = paging64_gva_to_gpa;
 		context->root_level = PT32E_ROOT_LEVEL;
 	} else {
-		reset_rsvds_bits_mask(vcpu, PT32_ROOT_LEVEL);
+		reset_rsvds_bits_mask(vcpu, context, PT32_ROOT_LEVEL);
 		context->gva_to_gpa = paging32_gva_to_gpa;
 		context->root_level = PT32_ROOT_LEVEL;
 	}
@@ -2743,24 +2745,32 @@ static int init_kvm_tdp_mmu(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
-static int init_kvm_softmmu(struct kvm_vcpu *vcpu)
+int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context)
 {
 	int r;
-
 	ASSERT(vcpu);
 	ASSERT(!VALID_PAGE(vcpu->arch.mmu.root_hpa));
 
 	if (!is_paging(vcpu))
-		r = nonpaging_init_context(vcpu);
+		r = nonpaging_init_context(vcpu, context);
 	else if (is_long_mode(vcpu))
-		r = paging64_init_context(vcpu);
+		r = paging64_init_context(vcpu, context);
 	else if (is_pae(vcpu))
-		r = paging32E_init_context(vcpu);
+		r = paging32E_init_context(vcpu, context);
 	else
-		r = paging32_init_context(vcpu);
+		r = paging32_init_context(vcpu, context);
 
 	vcpu->arch.mmu.base_role.cr4_pae = !!is_pae(vcpu);
 	vcpu->arch.mmu.base_role.cr0_wp  = is_write_protection(vcpu);
+
+	return r;
+}
+EXPORT_SYMBOL_GPL(kvm_init_shadow_mmu);
+
+static int init_kvm_softmmu(struct kvm_vcpu *vcpu)
+{
+	int r = kvm_init_shadow_mmu(vcpu, &vcpu->arch.mmu);
+
 	vcpu->arch.mmu.set_cr3           = kvm_x86_ops->set_cr3;
 	vcpu->arch.mmu.get_cr3           = get_cr3;
 	vcpu->arch.mmu.inject_page_fault = kvm_inject_page_fault;

arch/x86/kvm/mmu.h

@@ -49,6 +49,7 @@
 #define PFERR_FETCH_MASK (1U << 4)
 
 int kvm_mmu_get_spte_hierarchy(struct kvm_vcpu *vcpu, u64 addr, u64 sptes[4]);
+int kvm_init_shadow_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *context);
 
 static inline unsigned int kvm_mmu_available_pages(struct kvm *kvm)
 {