Re: KVM: x86: fix mov immediate emulation for 64-bit operands

[Gleb Natapov <gleb@redhat.com>]

On Thu, Dec 06, 2012 at 09:55:10PM -0200, Marcelo Tosatti wrote:
> 
> From: Nadav Amit <nadav.amit@gmail.com>
> 
> MOV immediate instruction (opcodes 0xB8-0xBF) may take 64-bit operand.
> The previous emulation implementation assumes the operand is no longer than 32.
> Adding OpImm64 for this matter.
> 
> Fixes https://bugzilla.redhat.com/show_bug.cgi?id=881579
> 
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> 
Needs author's sign-off and test case.

> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index 39171cb..6fec09c 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -43,7 +43,7 @@
>  #define OpCL               9ull  /* CL register (for shifts) */
>  #define OpImmByte         10ull  /* 8-bit sign extended immediate */
>  #define OpOne             11ull  /* Implied 1 */
> -#define OpImm             12ull  /* Sign extended immediate */
> +#define OpImm             12ull  /* Sign extended up to 32-bit immediate */
>  #define OpMem16           13ull  /* Memory operand (16-bit). */
>  #define OpMem32           14ull  /* Memory operand (32-bit). */
>  #define OpImmU            15ull  /* Immediate operand, zero extended */
> @@ -58,6 +58,7 @@
>  #define OpFS              24ull  /* FS */
>  #define OpGS              25ull  /* GS */
>  #define OpMem8            26ull  /* 8-bit zero extended memory operand */
> +#define OpImm64           27ull  /* Sign extended 16/32/64-bit immediate */
>  
>  #define OpBits             5  /* Width of operand field */
>  #define OpMask             ((1ull << OpBits) - 1)
> @@ -101,6 +102,7 @@
>  #define SrcMemFAddr (OpMemFAddr << SrcShift)
>  #define SrcAcc      (OpAcc << SrcShift)
>  #define SrcImmU16   (OpImmU16 << SrcShift)
> +#define SrcImm64    (OpImm64 << SrcShift)
>  #define SrcDX       (OpDX << SrcShift)
>  #define SrcMem8     (OpMem8 << SrcShift)
>  #define SrcMask     (OpMask << SrcShift)
> @@ -3786,7 +3788,7 @@ static const struct opcode opcode_table[256] = {
>  	/* 0xB0 - 0xB7 */
>  	X8(I(ByteOp | DstReg | SrcImm | Mov, em_mov)),
>  	/* 0xB8 - 0xBF */
> -	X8(I(DstReg | SrcImm | Mov, em_mov)),
> +	X8(I(DstReg | SrcImm64 | Mov, em_mov)),
>  	/* 0xC0 - 0xC7 */
>  	D2bv(DstMem | SrcImmByte | ModRM),
>  	I(ImplicitOps | Stack | SrcImmU16, em_ret_near_imm),
> @@ -3950,6 +3952,9 @@ static int decode_imm(struct x86_emulate_ctxt *ctxt, struct operand *op,
>  	case 4:
>  		op->val = insn_fetch(s32, ctxt);
>  		break;
> +	case 8:
> +		op->val = insn_fetch(s64, ctxt);
> +		break;
>  	}
>  	if (!sign_extension) {
>  		switch (op->bytes) {
> @@ -4028,6 +4033,9 @@ static int decode_operand(struct x86_emulate_ctxt *ctxt, struct operand *op,
>  	case OpImm:
>  		rc = decode_imm(ctxt, op, imm_size(ctxt), true);
>  		break;
> +	case OpImm64:
> +		rc = decode_imm(ctxt, op, ctxt->op_bytes, true);
> +		break;
>  	case OpMem8:
>  		ctxt->memop.bytes = 1;
>  		goto mem_common;

--
			Gleb.