linux-kernel - RE: [PATCH v10 11/15] platform/x86: dell-smbios-smm: test for WSMT

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Date:   Thu, 19 Oct 2017 18:12:09 +0000
From:   <Mario.Limonciello@...l.com>
To:     <pali.rohar@...il.com>
CC:     <dvhart@...radead.org>, <andy.shevchenko@...il.com>,
        <linux-kernel@...r.kernel.org>,
        <platform-driver-x86@...r.kernel.org>, <luto@...nel.org>,
        <quasisec@...gle.com>, <rjw@...ysocki.net>, <mjg59@...gle.com>,
        <hch@....de>, <greg@...ah.com>, <gnomes@...rguk.ukuu.org.uk>
Subject: RE: [PATCH v10 11/15] platform/x86: dell-smbios-smm: test for WSMT

> -----Original Message-----
> From: Pali Rohár [mailto:pali.rohar@...il.com]
> Sent: Thursday, October 19, 2017 1:09 PM
> To: Limonciello, Mario <Mario_Limonciello@...l.com>
> Cc: dvhart@...radead.org; Andy Shevchenko <andy.shevchenko@...il.com>;
> LKML <linux-kernel@...r.kernel.org>; platform-driver-x86@...r.kernel.org; Andy
> Lutomirski <luto@...nel.org>; quasisec@...gle.com; rjw@...ysocki.net;
> mjg59@...gle.com; hch@....de; Greg KH <greg@...ah.com>; Alan Cox
> <gnomes@...rguk.ukuu.org.uk>
> Subject: Re: [PATCH v10 11/15] platform/x86: dell-smbios-smm: test for WSMT
> 
> On Thursday 19 October 2017 12:50:14 Mario Limonciello wrote:
> > +/* When enabled this indicates that SMM won't work */
> > +static bool test_wsmt_enabled(void)
> > +{
> > +	struct calling_interface_token *token;
> > +
> > +	/* if token doesn't exist, SMM will work */
> > +	token = dell_smbios_find_token(WSMT_EN_TOKEN);
> > +	if (!token)
> > +		return false;
> > +
> > +	/* if token exists, try to access over SMM */
> > +	buffer->class = CLASS_TOKEN_READ;
> > +	buffer->select = SELECT_TOKEN_STD;
> > +	memset(buffer, 0, sizeof(struct calling_interface_buffer));
> > +	buffer->input[0] = token->location;
> > +	dell_smbios_smm_call(buffer);
> > +
> > +	/* if lookup failed, we know WSMT was enabled */
> > +	if (buffer->output[0] != 0)
> > +		return true;
> > +
> > +	/* query token status if it didn't fail */
> > +	return (buffer->output[1] == token->value);
> > +}
> > +
> >  static int __init dell_smbios_smm_init(void)
> >  {
> >  	int ret;
> > @@ -115,6 +140,13 @@ static int __init dell_smbios_smm_init(void)
> >
> >  	dmi_walk(find_cmd_address, NULL);
> >
> > +	ret = test_wsmt_enabled();
> 
> ret is int, but test_wsmt_enabled() returns bool.

Yes, ret is re-used within this method.
0, 1 enum is a subset of int, so this seemed like a logical thing to me to do.