This patch adds code to initialize the Nested Nested Paging
MMU context when the L1 guest executes a VMRUN instruction
and has nested paging enabled in its VMCB.

Signed-off-by: Joerg Roedel <joerg.roe...@amd.com>
---
 arch/x86/kvm/mmu.c |    1 +
 arch/x86/kvm/svm.c |   56 ++++++++++++++++++++++++++++++++++++++++++---------
 2 files changed, 47 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index ccaf6b1..b929d84 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2573,6 +2573,7 @@ void kvm_mmu_unload(struct kvm_vcpu *vcpu)
 {
        mmu_free_roots(vcpu);
 }
+EXPORT_SYMBOL_GPL(kvm_mmu_unload);
 
 static void mmu_pte_write_zap_pte(struct kvm_vcpu *vcpu,
                                  struct kvm_mmu_page *sp,
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index a6c08e0..bce10fe 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -93,7 +93,6 @@ struct nested_state {
 
        /* Nested Paging related state */
        u64 nested_cr3;
-
 };
 
 #define MSRPM_OFFSETS  16
@@ -282,6 +281,15 @@ static inline void flush_guest_tlb(struct kvm_vcpu *vcpu)
        force_new_asid(vcpu);
 }
 
+static int get_npt_level(void)
+{
+#ifdef CONFIG_X86_64
+       return PT64_ROOT_LEVEL;
+#else
+       return PT32E_ROOT_LEVEL;
+#endif
+}
+
 static void svm_set_efer(struct kvm_vcpu *vcpu, u64 efer)
 {
        if (!npt_enabled && !(efer & EFER_LMA))
@@ -1578,6 +1586,27 @@ static void nested_svm_inject_npf_exit(struct kvm_vcpu 
*vcpu,
        nested_svm_vmexit(svm);
 }
 
+static int nested_svm_init_mmu_context(struct kvm_vcpu *vcpu)
+{
+       int r;
+
+       r = kvm_init_shadow_mmu(vcpu, &vcpu->arch.mmu);
+
+       vcpu->arch.mmu.set_cr3           = nested_svm_set_tdp_cr3;
+       vcpu->arch.mmu.get_cr3           = nested_svm_get_tdp_cr3;
+       vcpu->arch.mmu.inject_page_fault = nested_svm_inject_npf_exit;
+       vcpu->arch.mmu.shadow_root_level = get_npt_level();
+       vcpu->arch.nested_mmu.gva_to_gpa = vcpu->arch.mmu.gva_to_gpa;
+       vcpu->arch.mmu.nested            = true;
+
+       return r;
+}
+
+static void nested_svm_uninit_mmu_context(struct kvm_vcpu *vcpu)
+{
+       vcpu->arch.mmu.nested = false;
+}
+
 static int nested_svm_check_permissions(struct vcpu_svm *svm)
 {
        if (!(svm->vcpu.arch.efer & EFER_SVME)
@@ -1942,6 +1971,8 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
        kvm_clear_exception_queue(&svm->vcpu);
        kvm_clear_interrupt_queue(&svm->vcpu);
 
+       svm->nested.nested_cr3 = 0;
+
        /* Restore selected save entries */
        svm->vmcb->save.es = hsave->save.es;
        svm->vmcb->save.cs = hsave->save.cs;
@@ -1968,6 +1999,7 @@ static int nested_svm_vmexit(struct vcpu_svm *svm)
 
        nested_svm_unmap(page);
 
+       nested_svm_uninit_mmu_context(&svm->vcpu);
        kvm_mmu_reset_context(&svm->vcpu);
        kvm_mmu_load(&svm->vcpu);
 
@@ -2021,6 +2053,13 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
        if (!nested_vmcb)
                return false;
 
+       /* Do check if nested paging is allowed for the guest */
+       if (nested_vmcb->control.nested_ctl && !npt_enabled) {
+               nested_vmcb->control.exit_code = SVM_EXIT_ERR;
+               nested_svm_unmap(page);
+               return false;
+       }
+
        trace_kvm_nested_vmrun(svm->vmcb->save.rip - 3, vmcb_gpa,
                               nested_vmcb->save.rip,
                               nested_vmcb->control.int_ctl,
@@ -2065,6 +2104,12 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm)
        else
                svm->vcpu.arch.hflags &= ~HF_HIF_MASK;
 
+       if (nested_vmcb->control.nested_ctl) {
+               kvm_mmu_unload(&svm->vcpu);
+               svm->nested.nested_cr3 = nested_vmcb->control.nested_cr3;
+               nested_svm_init_mmu_context(&svm->vcpu);
+       }
+
        /* Load the nested guest state */
        svm->vmcb->save.es = nested_vmcb->save.es;
        svm->vmcb->save.cs = nested_vmcb->save.cs;
@@ -3233,15 +3278,6 @@ static bool svm_cpu_has_accelerated_tpr(void)
        return false;
 }
 
-static int get_npt_level(void)
-{
-#ifdef CONFIG_X86_64
-       return PT64_ROOT_LEVEL;
-#else
-       return PT32E_ROOT_LEVEL;
-#endif
-}
-
 static u64 svm_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
 {
        return 0;
-- 
1.7.0


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