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KVM: x86: Use macros for x86_emulate_ops to avoid future mistakes
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The return values from x86_emulate_ops are defined
in kvm_emulate.h as macros X86EMUL_*.

But in emulate.c, we are comparing the return values
from these ops with 0 to check if they're X86EMUL_CONTINUE
or not: X86EMUL_CONTINUE is defined as 0 now.

To avoid possible mistakes in the future, this patch
substitutes "X86EMUL_CONTINUE" for "0" that are being
compared with the return values from x86_emulate_ops.

  We think that there are more places we should use these
  macros, but the meanings of rc values in x86_emulate_insn()
  were not so clear at a glance. If we use proper macros in
  this function, we would be able to follow the flow of each
  emulation more easily and, maybe, more securely.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
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Takuya Yoshikawa authored and Marcelo Tosatti committed Mar 1, 2010
1 parent 6474920 commit b60d513
Showing 1 changed file with 36 additions and 29 deletions.
65 changes: 36 additions & 29 deletions arch/x86/kvm/emulate.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1196,7 +1196,7 @@ static int emulate_pop(struct x86_emulate_ctxt *ctxt,
rc = ops->read_emulated(register_address(c, ss_base(ctxt),
c->regs[VCPU_REGS_RSP]),
dest, len, ctxt->vcpu);
if (rc != 0)
if (rc != X86EMUL_CONTINUE)
return rc;

register_address_increment(c, &c->regs[VCPU_REGS_RSP], len);
Expand Down Expand Up @@ -1370,7 +1370,7 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
int rc;

rc = ops->read_emulated(memop, &old, 8, ctxt->vcpu);
if (rc != 0)
if (rc != X86EMUL_CONTINUE)
return rc;

if (((u32) (old >> 0) != (u32) c->regs[VCPU_REGS_RAX]) ||
Expand All @@ -1385,7 +1385,7 @@ static inline int emulate_grp9(struct x86_emulate_ctxt *ctxt,
(u32) c->regs[VCPU_REGS_RBX];

rc = ops->cmpxchg_emulated(memop, &old, &new, 8, ctxt->vcpu);
if (rc != 0)
if (rc != X86EMUL_CONTINUE)
return rc;
ctxt->eflags |= EFLG_ZF;
}
Expand Down Expand Up @@ -1451,7 +1451,7 @@ static inline int writeback(struct x86_emulate_ctxt *ctxt,
&c->dst.val,
c->dst.bytes,
ctxt->vcpu);
if (rc != 0)
if (rc != X86EMUL_CONTINUE)
return rc;
break;
case OP_NONE:
Expand Down Expand Up @@ -1749,7 +1749,7 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
&c->src.val,
c->src.bytes,
ctxt->vcpu);
if (rc != 0)
if (rc != X86EMUL_CONTINUE)
goto done;
c->src.orig_val = c->src.val;
}
Expand All @@ -1768,12 +1768,15 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
c->dst.ptr = (void *)c->dst.ptr +
(c->src.val & mask) / 8;
}
if (!(c->d & Mov) &&
/* optimisation - avoid slow emulated read */
((rc = ops->read_emulated((unsigned long)c->dst.ptr,
&c->dst.val,
c->dst.bytes, ctxt->vcpu)) != 0))
goto done;
if (!(c->d & Mov)) {
/* optimisation - avoid slow emulated read */
rc = ops->read_emulated((unsigned long)c->dst.ptr,
&c->dst.val,
c->dst.bytes,
ctxt->vcpu);
if (rc != X86EMUL_CONTINUE)
goto done;
}
}
c->dst.orig_val = c->dst.val;

Expand Down Expand Up @@ -2039,11 +2042,12 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
c->dst.ptr = (unsigned long *)register_address(c,
es_base(ctxt),
c->regs[VCPU_REGS_RDI]);
if ((rc = ops->read_emulated(register_address(c,
seg_override_base(ctxt, c),
c->regs[VCPU_REGS_RSI]),
rc = ops->read_emulated(register_address(c,
seg_override_base(ctxt, c),
c->regs[VCPU_REGS_RSI]),
&c->dst.val,
c->dst.bytes, ctxt->vcpu)) != 0)
c->dst.bytes, ctxt->vcpu);
if (rc != X86EMUL_CONTINUE)
goto done;
register_address_increment(c, &c->regs[VCPU_REGS_RSI],
(ctxt->eflags & EFLG_DF) ? -c->dst.bytes
Expand All @@ -2058,21 +2062,23 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
c->src.ptr = (unsigned long *)register_address(c,
seg_override_base(ctxt, c),
c->regs[VCPU_REGS_RSI]);
if ((rc = ops->read_emulated((unsigned long)c->src.ptr,
&c->src.val,
c->src.bytes,
ctxt->vcpu)) != 0)
rc = ops->read_emulated((unsigned long)c->src.ptr,
&c->src.val,
c->src.bytes,
ctxt->vcpu);
if (rc != X86EMUL_CONTINUE)
goto done;

c->dst.type = OP_NONE; /* Disable writeback. */
c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
c->dst.ptr = (unsigned long *)register_address(c,
es_base(ctxt),
c->regs[VCPU_REGS_RDI]);
if ((rc = ops->read_emulated((unsigned long)c->dst.ptr,
&c->dst.val,
c->dst.bytes,
ctxt->vcpu)) != 0)
rc = ops->read_emulated((unsigned long)c->dst.ptr,
&c->dst.val,
c->dst.bytes,
ctxt->vcpu);
if (rc != X86EMUL_CONTINUE)
goto done;

DPRINTF("cmps: mem1=0x%p mem2=0x%p\n", c->src.ptr, c->dst.ptr);
Expand Down Expand Up @@ -2102,12 +2108,13 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
c->dst.type = OP_REG;
c->dst.bytes = (c->d & ByteOp) ? 1 : c->op_bytes;
c->dst.ptr = (unsigned long *)&c->regs[VCPU_REGS_RAX];
if ((rc = ops->read_emulated(register_address(c,
seg_override_base(ctxt, c),
c->regs[VCPU_REGS_RSI]),
&c->dst.val,
c->dst.bytes,
ctxt->vcpu)) != 0)
rc = ops->read_emulated(register_address(c,
seg_override_base(ctxt, c),
c->regs[VCPU_REGS_RSI]),
&c->dst.val,
c->dst.bytes,
ctxt->vcpu);
if (rc != X86EMUL_CONTINUE)
goto done;
register_address_increment(c, &c->regs[VCPU_REGS_RSI],
(ctxt->eflags & EFLG_DF) ? -c->dst.bytes
Expand Down

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