KVM: x86 emulator: fix mov dr to inject #UD when needed.

If CR4.DE=1 access to registers DR4/DR5 cause #UD.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 836e97b..5afddcf 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2531,9 +2531,12 @@ twobyte_insn:
                c->dst.type = OP_NONE;  /* no writeback */
                break;
        case 0x21: /* mov from dr to reg */
-               if (emulator_get_dr(ctxt, c->modrm_reg, &c->regs[c->modrm_rm]))
-                       goto cannot_emulate;
-               rc = X86EMUL_CONTINUE;
+               if ((ops->get_cr(4, ctxt->vcpu) & X86_CR4_DE) &&
+                   (c->modrm_reg == 4 || c->modrm_reg == 5)) {
+                       kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                       goto done;
+               }
+               emulator_get_dr(ctxt, c->modrm_reg, &c->regs[c->modrm_rm]);
                c->dst.type = OP_NONE;  /* no writeback */
                break;
        case 0x22: /* mov reg, cr */
@@ -2541,9 +2544,12 @@ twobyte_insn:
                c->dst.type = OP_NONE;
                break;
        case 0x23: /* mov from reg to dr */
-               if (emulator_set_dr(ctxt, c->modrm_reg, c->regs[c->modrm_rm]))
-                       goto cannot_emulate;
-               rc = X86EMUL_CONTINUE;
+               if ((ops->get_cr(4, ctxt->vcpu) & X86_CR4_DE) &&
+                   (c->modrm_reg == 4 || c->modrm_reg == 5)) {
+                       kvm_queue_exception(ctxt->vcpu, UD_VECTOR);
+                       goto done;
+               }
+               emulator_set_dr(ctxt, c->modrm_reg, c->regs[c->modrm_rm]);
                c->dst.type = OP_NONE;  /* no writeback */
                break;
        case 0x30: