linux-kernel - Re: [PATCH 3/3] KVM: x86 emulator: trap and propagate #DE from DIV and IDIV

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Date:	Wed, 25 Aug 2010 18:05:02 -0300
From:	Marcelo Tosatti <mtosatti@...hat.com>
To:	Avi Kivity <avi@...hat.com>
Cc:	x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] KVM: x86 emulator: trap and propagate #DE from DIV
 and IDIV

On Tue, Aug 24, 2010 at 02:10:29PM +0300, Avi Kivity wrote:
> Signed-off-by: Avi Kivity <avi@...hat.com>
> ---
>  arch/x86/kvm/emulate.c |   17 ++++++++++++++---
>  1 files changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
> index f82e43a..a7e26d0 100644
> --- a/arch/x86/kvm/emulate.c
> +++ b/arch/x86/kvm/emulate.c
> @@ -505,6 +505,12 @@ static void emulate_ts(struct x86_emulate_ctxt *ctxt, int err)
>  	emulate_exception(ctxt, TS_VECTOR, err, true);
>  }
>  
> +static int emulate_de(struct x86_emulate_ctxt *ctxt)
> +{
> +	emulate_exception(ctxt, DE_VECTOR, 0, false);
> +	return X86EMUL_PROPAGATE_FAULT;
> +}
> +
>  static int do_fetch_insn_byte(struct x86_emulate_ctxt *ctxt,
>  			      struct x86_emulate_ops *ops,
>  			      unsigned long eip, u8 *dest)
> @@ -1459,6 +1465,7 @@ static inline int emulate_grp3(struct x86_emulate_ctxt *ctxt,
>  	struct decode_cache *c = &ctxt->decode;
>  	unsigned long *rax = &c->regs[VCPU_REGS_RAX];
>  	unsigned long *rdx = &c->regs[VCPU_REGS_RDX];
> +	u8 de = 0;
>  
>  	switch (c->modrm_reg) {
>  	case 0 ... 1:	/* test */
> @@ -1477,14 +1484,18 @@ static inline int emulate_grp3(struct x86_emulate_ctxt *ctxt,
>  		emulate_1op_rax_rdx("imul", c->src, *rax, *rdx, ctxt->eflags);
>  		break;
>  	case 6: /* div */
> -		emulate_1op_rax_rdx("div", c->src, *rax, *rdx, ctxt->eflags);
> +		emulate_1op_rax_rdx_ex("div", c->src, *rax, *rdx,
> +				       ctxt->eflags, de);
>  		break;
>  	case 7: /* idiv */
> -		emulate_1op_rax_rdx("idiv", c->src, *rax, *rdx, ctxt->eflags);
> +		emulate_1op_rax_rdx_ex("idiv", c->src, *rax, *rdx,
> +				       ctxt->eflags, de);
>  		break;
>  	default:
>  		return X86EMUL_UNHANDLEABLE;
>  	}
> +	if (de)
> +		return emulate_de(ctxt);
>  	return X86EMUL_CONTINUE;
>  }
>  
> @@ -3363,7 +3374,7 @@ special_insn:
>  		break;
>  	case 0xf6 ... 0xf7:	/* Grp3 */
>  		if (emulate_grp3(ctxt, ops) != X86EMUL_CONTINUE)
> -			goto cannot_emulate;
> +			goto done;
>  		break;

Must assign rc to emulate_grp3() retval.

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