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>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 136088f..7e4a45c 100644 (file)
--- 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);
 }