KVM: x86 emulator: handle undecoded rex.b with r/m = 5 in certain cases

x86_64 does not decode rex.b in certain cases, where the r/m field = 5.

Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index 28082913919e..3721cfddc973 100644
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -750,6 +750,7 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
 
                         switch (base_reg) {
                         case 5:
+                        case 13:
                                 if (c->modrm_mod != 0)
                                         c->modrm_ea += c->regs[base_reg];
                                 else
@@ -767,6 +768,7 @@ static int decode_modrm(struct x86_emulate_ctxt *ctxt,
                         }
                         break;
                 case 5:
+                case 13:
                         if (c->modrm_mod != 0)
                                 c->modrm_ea += c->regs[c->modrm_rm];
                         else if (ctxt->mode == X86EMUL_MODE_PROT64)