+static int check_dr7_gd(struct x86_emulate_ctxt *ctxt)
+{
+ unsigned long dr7;
+
+ ctxt->ops->get_dr(7, &dr7, ctxt->vcpu);
+
+ /* Check if DR7.Global_Enable is set */
+ return dr7 & (1 << 13);
+}
+
+static int check_dr_read(struct x86_emulate_ctxt *ctxt)
+{
+ struct decode_cache *c = &ctxt->decode;
+ int dr = c->modrm_reg;
+ u64 cr4;
+
+ if (dr > 7)
+ return emulate_ud(ctxt);
+
+ cr4 = ctxt->ops->get_cr(4, ctxt->vcpu);
+ if ((cr4 & X86_CR4_DE) && (dr == 4 || dr == 5))
+ return emulate_ud(ctxt);
+
+ if (check_dr7_gd(ctxt))
+ return emulate_db(ctxt);
+
+ return X86EMUL_CONTINUE;
+}
+
+static int check_dr_write(struct x86_emulate_ctxt *ctxt)
+{
+ struct decode_cache *c = &ctxt->decode;
+ u64 new_val = c->src.val64;
+ int dr = c->modrm_reg;
+
+ if ((dr == 6 || dr == 7) && (new_val & 0xffffffff00000000ULL))
+ return emulate_gp(ctxt, 0);
+
+ return check_dr_read(ctxt);
+}
+