KVM: x86: Loading segments on 64-bit mode may be wrong

The current emulator implementation ignores the high 32 bits of the base in
long-mode.  During segment load from the LDT, the base of the LDT is calculated
incorrectly and may cause the wrong segment to be loaded.

Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 136088fb038b..7e4a45cab400 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -1358,17 +1358,19 @@ static void get_descriptor_table_ptr(struct x86_emulate_ctxt *ctxt,
                                      u16 selector, struct desc_ptr *dt)
 {
         const struct x86_emulate_ops *ops = ctxt->ops;
+        u32 base3 = 0;
 
         if (selector & 1 << 2) {
                 struct desc_struct desc;
                 u16 sel;
 
                 memset (dt, 0, sizeof *dt);
-                if (!ops->get_segment(ctxt, &sel, &desc, NULL, VCPU_SREG_LDTR))
+                if (!ops->get_segment(ctxt, &sel, &desc, &base3,
+                                      VCPU_SREG_LDTR))
                         return;
 
                 dt->size = desc_limit_scaled(&desc); /* what if limit > 65535? */
-                dt->address = get_desc_base(&desc);
+                dt->address = get_desc_base(&desc) | ((u64)base3 << 32);
         } else
                 ops->get_gdt(ctxt, dt);
 }