KVM: x86: Fix wrong masking on relative jump/call

Relative jumps and calls do the masking according to the operand size, and not
according to the address size as the KVM emulator does today.

This patch fixes KVM behavior.

Cc: stable@vger.kernel.org
Signed-off-by: Nadav Amit <namit@cs.technion.ac.il>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index a46207a0583508ad662d179f2db1ede320a7645e..04769897479951b7c2f7157f1a1792340d15f9a4 100644 (file)
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -504,11 +504,6 @@ static void rsp_increment(struct x86_emulate_ctxt *ctxt, int inc)
        masked_increment(reg_rmw(ctxt, VCPU_REGS_RSP), stack_mask(ctxt), inc);
 }
 
-static inline void jmp_rel(struct x86_emulate_ctxt *ctxt, int rel)
-{
-       register_address_increment(ctxt, &ctxt->_eip, rel);
-}
-
 static u32 desc_limit_scaled(struct desc_struct *desc)
 {
        u32 limit = get_desc_limit(desc);
@@ -569,6 +564,28 @@ static int emulate_nm(struct x86_emulate_ctxt *ctxt)
        return emulate_exception(ctxt, NM_VECTOR, 0, false);
 }
 
+static inline void assign_eip_near(struct x86_emulate_ctxt *ctxt, ulong dst)
+{
+       switch (ctxt->op_bytes) {
+       case 2:
+               ctxt->_eip = (u16)dst;
+               break;
+       case 4:
+               ctxt->_eip = (u32)dst;
+               break;
+       case 8:
+               ctxt->_eip = dst;
+               break;
+       default:
+               WARN(1, "unsupported eip assignment size\n");
+       }
+}
+
+static inline void jmp_rel(struct x86_emulate_ctxt *ctxt, int rel)
+{
+       assign_eip_near(ctxt, ctxt->_eip + rel);
+}
+
 static u16 get_segment_selector(struct x86_emulate_ctxt *ctxt, unsigned seg)
 {
        u16 selector;