KVM: x86 emulator: fix writes to registers with modrm encodings
A register destination encoded with a mod=3 encoding left dst.ptr NULL.
Normally we don't trap writes to registers, but in the case of smsw, we do.
Fix by pointing dst.ptr at the destination register.
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/x86_emulate.c b/arch/x86/kvm/x86_emulate.c
index f2a696d..8a96320 100644
--- a/arch/x86/kvm/x86_emulate.c
+++ b/arch/x86/kvm/x86_emulate.c
@@ -677,8 +677,9 @@
c->use_modrm_ea = 1;
if (c->modrm_mod == 3) {
- c->modrm_val = *(unsigned long *)
- decode_register(c->modrm_rm, c->regs, c->d & ByteOp);
+ c->modrm_ptr = decode_register(c->modrm_rm,
+ c->regs, c->d & ByteOp);
+ c->modrm_val = *(unsigned long *)c->modrm_ptr;
return rc;
}
@@ -1005,6 +1006,7 @@
if ((c->d & ModRM) && c->modrm_mod == 3) {
c->src.type = OP_REG;
c->src.val = c->modrm_val;
+ c->src.ptr = c->modrm_ptr;
break;
}
c->src.type = OP_MEM;
@@ -1049,6 +1051,7 @@
if ((c->d & ModRM) && c->modrm_mod == 3) {
c->dst.type = OP_REG;
c->dst.val = c->dst.orig_val = c->modrm_val;
+ c->dst.ptr = c->modrm_ptr;
break;
}
c->dst.type = OP_MEM;