KVM: X86: Add kvm_read_guest_page_mmu function

This patch adds a function which can read from the guests
physical memory or from the guest's guest physical memory.
This will be used in the two-dimensional page table walker.

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

2 files changed, 26 insertions, 0 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 8ec3547c433d..08bc383083ff 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -657,6 +657,9 @@ void kvm_queue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
 void kvm_requeue_exception(struct kvm_vcpu *vcpu, unsigned nr);
 void kvm_requeue_exception_e(struct kvm_vcpu *vcpu, unsigned nr, u32 error_code);
 void kvm_inject_page_fault(struct kvm_vcpu *vcpu);
+int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
+                            gfn_t gfn, void *data, int offset, int len,
+                            u32 access);
 bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl);
 
 int kvm_pic_set_irq(void *opaque, int irq, int level);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4196fc719142..a2efb70f4cc8 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -370,6 +370,29 @@ bool kvm_require_cpl(struct kvm_vcpu *vcpu, int required_cpl)
 EXPORT_SYMBOL_GPL(kvm_require_cpl);
 
 /*
+ * This function will be used to read from the physical memory of the currently
+ * running guest. The difference to kvm_read_guest_page is that this function
+ * can read from guest physical or from the guest's guest physical memory.
+ */
+int kvm_read_guest_page_mmu(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
+                            gfn_t ngfn, void *data, int offset, int len,
+                            u32 access)
+{
+        gfn_t real_gfn;
+        gpa_t ngpa;
+
+        ngpa     = gfn_to_gpa(ngfn);
+        real_gfn = mmu->translate_gpa(vcpu, ngpa, access);
+        if (real_gfn == UNMAPPED_GVA)
+                return -EFAULT;
+
+        real_gfn = gpa_to_gfn(real_gfn);
+
+        return kvm_read_guest_page(vcpu->kvm, real_gfn, data, offset, len);
+}
+EXPORT_SYMBOL_GPL(kvm_read_guest_page_mmu);
+
+/*
  * Load the pae pdptrs.  Return true is they are all valid.
  */
 int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)