Re: KVM: x86: use proper port value when checking io instruction permission (v2)

[Avi Kivity <avi@redhat.com>]

On 05/25/2011 09:18 PM, Marcelo Tosatti wrote:
> Commit fa4491a6b667304 moved the permission check for io instructions
> to the ->check_perm callback. It failed to copy the port value from RDX
> register for string and "in,out ax,dx" instructions.
>
> Fix it by reading RDX register at decode stage when appropriate.
>
> Fixes FC8.32 installation.
>
> +#define Sse         (1<<18)     /* SSE Vector instruction */

19/20 are still available, no need to go 64-bit just yet.

>   /* Misc flags */
> -#define Prot        (1<<21) /* instruction generates #UD if not in prot-mode */
>
> +	case SrcDX:
> +		c->src.type = OP_REG;
> +		c->src.bytes = c->op_bytes;

Needs to be 2.  Otherwise we'll see extra bits from edx, or lose bits 
from dx if it's a 1-byte instruction.

> +		c->src.addr.reg =&c->regs[VCPU_REGS_RDX];
> +		fetch_register_operand(&c->src);
> +		break;
>   	}
>
>   	if (rc != X86EMUL_CONTINUE)
> @@ -3649,6 +3657,12 @@ done_prefixes:
>   		c->dst.addr.mem.seg = VCPU_SREG_ES;
>   		c->dst.val = 0;
>   		break;
> +	case DstDX:
> +		c->dst.type = OP_REG;
> +		c->dst.bytes = c->op_bytes;

2 again.

> +		c->dst.addr.reg =&c->regs[VCPU_REGS_RDX];
> +		fetch_register_operand(&c->dst);
> +		break;
>   	case ImplicitOps:
>   		/* Special instructions do their own operand decoding. */
>   	default:

We also need to unify Src/Dst decode eventually.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.