KVM: x86 emulator: 0f (20|21|22|23) ignore mod bits.

Resent spec says that for 0f (20|21|22|23) the 2 bits in the mod field
are ignored. Interestingly enough older spec says that 11 is only valid
encoding.

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

1 files changed, 0 insertions, 8 deletions

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 7c7debb424d..fa4604e0325 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -2520,28 +2520,20 @@ twobyte_insn:
                 c->dst.type = OP_NONE;
                 break;
         case 0x20: /* mov cr, reg */
-                if (c->modrm_mod != 3)
-                        goto cannot_emulate;
                 c->regs[c->modrm_rm] = ops->get_cr(c->modrm_reg, ctxt->vcpu);
                 c->dst.type = OP_NONE;  /* no writeback */
                 break;
         case 0x21: /* mov from dr to reg */
-                if (c->modrm_mod != 3)
-                        goto cannot_emulate;
                 if (emulator_get_dr(ctxt, c->modrm_reg, &c->regs[c->modrm_rm]))
                         goto cannot_emulate;
                 rc = X86EMUL_CONTINUE;
                 c->dst.type = OP_NONE;  /* no writeback */
                 break;
         case 0x22: /* mov reg, cr */
-                if (c->modrm_mod != 3)
-                        goto cannot_emulate;
                 ops->set_cr(c->modrm_reg, c->modrm_val, ctxt->vcpu);
                 c->dst.type = OP_NONE;
                 break;
         case 0x23: /* mov from reg to dr */
-                if (c->modrm_mod != 3)
-                        goto cannot_emulate;
                 if (emulator_set_dr(ctxt, c->modrm_reg, c->regs[c->modrm_rm]))
                         goto cannot_emulate;
                 rc = X86EMUL_CONTINUE;