KVM: x86: use proper port value when checking io instruction permission (v3)

[Marcelo Tosatti <mtosatti@redhat.com>]

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.

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 3bc6b7a..fc3d2d9 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -47,7 +47,7 @@
 #define DstDI       (5<<1)	/* Destination is in ES:(E)DI */
 #define DstMem64    (6<<1)	/* 64bit memory operand */
 #define DstImmUByte (7<<1)	/* 8-bit unsigned immediate operand */
-#define DstMask     (7<<1)
+#define DstMask     ((7<<1) | (1<<18))
 /* Source operand type. */
 #define SrcNone     (0<<4)	/* No source operand. */
 #define SrcReg      (1<<4)	/* Register operand. */
@@ -64,7 +64,7 @@
 #define SrcMemFAddr (0xc<<4)	/* Source is far address in memory */
 #define SrcAcc      (0xd<<4)	/* Source Accumulator */
 #define SrcImmU16   (0xe<<4)    /* Immediate operand, unsigned, 16 bits */
-#define SrcMask     (0xf<<4)
+#define SrcMask     ((0xf<<4) | (1<<19))
 /* Generic ModRM decode. */
 #define ModRM       (1<<8)
 /* Destination is only written; never read. */
@@ -79,6 +79,8 @@
 #define Prefix      (3<<14)     /* Instruction varies with 66/f2/f3 prefix */
 #define RMExt       (4<<14)     /* Opcode extension in ModRM r/m if mod == 3 */
 #define Sse         (1<<17)     /* SSE Vector instruction */
+#define DstDX       (1<<18)	/* Destination is in DX register */
+#define SrcDX       (1<<19)	/* Source is in DX register */
 /* Misc flags */
 #define Prot        (1<<21) /* instruction generates #UD if not in prot-mode */
 #define VendorSpecific (1<<22) /* Vendor specific instruction */
@@ -3124,8 +3126,8 @@ static struct opcode opcode_table[256] = {
 	I(DstReg | SrcMem | ModRM | Src2Imm, em_imul_3op),
 	I(SrcImmByte | Mov | Stack, em_push),
 	I(DstReg | SrcMem | ModRM | Src2ImmByte, em_imul_3op),
-	D2bvIP(DstDI | Mov | String, ins, check_perm_in), /* insb, insw/insd */
-	D2bvIP(SrcSI | ImplicitOps | String, outs, check_perm_out), /* outsb, outsw/outsd */
+	D2bvIP(DstDI | SrcDX | Mov | String, ins, check_perm_in), /* insb, insw/insd */
+	D2bvIP(SrcSI | DstDX | String, outs, check_perm_out), /* outsb, outsw/outsd */
 	/* 0x70 - 0x7F */
 	X16(D(SrcImmByte)),
 	/* 0x80 - 0x87 */
@@ -3182,8 +3184,8 @@ static struct opcode opcode_table[256] = {
 	/* 0xE8 - 0xEF */
 	D(SrcImm | Stack), D(SrcImm | ImplicitOps),
 	D(SrcImmFAddr | No64), D(SrcImmByte | ImplicitOps),
-	D2bvIP(SrcNone | DstAcc,     in,  check_perm_in),
-	D2bvIP(SrcAcc | ImplicitOps, out, check_perm_out),
+	D2bvIP(SrcDX | DstAcc, in,  check_perm_in),
+	D2bvIP(SrcAcc | DstDX, out, check_perm_out),
 	/* 0xF0 - 0xF7 */
 	N, DI(ImplicitOps, icebp), N, N,
 	DI(ImplicitOps | Priv, hlt), D(ImplicitOps),
@@ -3580,6 +3582,12 @@ done_prefixes:
 		memop.bytes = c->op_bytes + 2;
 		goto srcmem_common;
 		break;
+	case SrcDX:
+		c->src.type = OP_REG;
+		c->src.bytes = 2;
+		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 = 2;
+		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:
@@ -3993,7 +4007,6 @@ special_insn:
 		break;
 	case 0xec: /* in al,dx */
 	case 0xed: /* in (e/r)ax,dx */
-		c->src.val = c->regs[VCPU_REGS_RDX];
 	do_io_in:
 		if (!pio_in_emulated(ctxt, c->dst.bytes, c->src.val,
 				     &c->dst.val))
@@ -4001,7 +4014,6 @@ special_insn:
 		break;
 	case 0xee: /* out dx,al */
 	case 0xef: /* out dx,(e/r)ax */
-		c->dst.val = c->regs[VCPU_REGS_RDX];
 	do_io_out:
 		ops->pio_out_emulated(ctxt, c->src.bytes, c->dst.val,
 				      &c->src.val, 1);