KVM: MMU: Implement nested gva_to_gpa functions

This patch adds the functions to do a nested l2_gva to
l1_gpa page table walk.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

4 files changed, 54 insertions, 0 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1b3eb8a0a1bc..8ec3547c433d 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -296,6 +296,16 @@ struct kvm_vcpu_arch {
         struct kvm_mmu mmu;
 
         /*
+         * Paging state of an L2 guest (used for nested npt)
+         *
+         * This context will save all necessary information to walk page tables
+         * of the an L2 guest. This context is only initialized for page table
+         * walking and not for faulting since we never handle l2 page faults on
+         * the host.
+         */
+        struct kvm_mmu nested_mmu;
+
+        /*
          * Pointer to the mmu context currently used for
          * gva_to_gpa translations.
          */
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index cb06adac92b1..1e215e8b9377 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2466,6 +2466,14 @@ static gpa_t nonpaging_gva_to_gpa(struct kvm_vcpu *vcpu, gva_t vaddr,
         return vaddr;
 }
 
+static gpa_t nonpaging_gva_to_gpa_nested(struct kvm_vcpu *vcpu, gva_t vaddr,
+                                         u32 access, u32 *error)
+{
+        if (error)
+                *error = 0;
+        return vcpu->arch.nested_mmu.translate_gpa(vcpu, vaddr, access);
+}
+
 static int nonpaging_page_fault(struct kvm_vcpu *vcpu, gva_t gva,
                                 u32 error_code)
 {
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index a704a8130e44..eefe363156b9 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -276,6 +276,16 @@ static int FNAME(walk_addr)(struct guest_walker *walker,
                                         write_fault, user_fault, fetch_fault);
 }
 
+static int FNAME(walk_addr_nested)(struct guest_walker *walker,
+                                   struct kvm_vcpu *vcpu, gva_t addr,
+                                   int write_fault, int user_fault,
+                                   int fetch_fault)
+{
+        return FNAME(walk_addr_generic)(walker, vcpu, &vcpu->arch.nested_mmu,
+                                        addr, write_fault, user_fault,
+                                        fetch_fault);
+}
+
 static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
                               u64 *spte, const void *pte)
 {
@@ -660,6 +670,27 @@ static gpa_t FNAME(gva_to_gpa)(struct kvm_vcpu *vcpu, gva_t vaddr, u32 access,
         return gpa;
 }
 
+static gpa_t FNAME(gva_to_gpa_nested)(struct kvm_vcpu *vcpu, gva_t vaddr,
+                                      u32 access, u32 *error)
+{
+        struct guest_walker walker;
+        gpa_t gpa = UNMAPPED_GVA;
+        int r;
+
+        r = FNAME(walk_addr_nested)(&walker, vcpu, vaddr,
+                                    access & PFERR_WRITE_MASK,
+                                    access & PFERR_USER_MASK,
+                                    access & PFERR_FETCH_MASK);
+
+        if (r) {
+                gpa = gfn_to_gpa(walker.gfn);
+                gpa |= vaddr & ~PAGE_MASK;
+        } else if (error)
+                *error = walker.error_code;
+
+        return gpa;
+}
+
 static void FNAME(prefetch_page)(struct kvm_vcpu *vcpu,
                                  struct kvm_mmu_page *sp)
 {
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 2d6385e44ccf..bf4dc2f40d7f 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -50,6 +50,11 @@ static inline int is_long_mode(struct kvm_vcpu *vcpu)
 #endif
 }
 
+static inline bool mmu_is_nested(struct kvm_vcpu *vcpu)
+{
+        return vcpu->arch.walk_mmu == &vcpu->arch.nested_mmu;
+}
+
 static inline int is_pae(struct kvm_vcpu *vcpu)
 {
         return kvm_read_cr4_bits(vcpu, X86_CR4_PAE);