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Message-ID: <1db4686f-557c-6e24-f991-c59f337bd136@intel.com>
Date:   Wed, 2 Mar 2022 17:34:10 -0800
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Subject: Re: [RFC 01/10] x86/microcode/intel: expose collect_cpu_info_early()
 for IFS
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To:     Borislav Petkov <bp@alien8.de>
CC:     <hdegoede@redhat.com>, <markgross@kernel.org>,
        <tglx@linutronix.de>, <mingo@redhat.com>,
        <dave.hansen@linux.intel.com>, <x86@kernel.org>, <hpa@zytor.com>,
        <corbet@lwn.net>, <gregkh@linuxfoundation.org>,
        <andriy.shevchenko@linux.intel.com>, <ashok.raj@intel.com>,
        <tony.luck@intel.com>, <rostedt@goodmis.org>,
        <linux-kernel@vger.kernel.org>, <linux-doc@vger.kernel.org>,
        <platform-driver-x86@vger.kernel.org>, <patches@lists.linux.dev>,
        <ravi.v.shankar@intel.com>
References: <20220301195457.21152-1-jithu.joseph@intel.com>
 <20220301195457.21152-2-jithu.joseph@intel.com>
 <Yh9HKhESkcUIYzSr@nazgul.tnic>
From:   "Joseph, Jithu" <jithu.joseph@intel.com>
In-Reply-To: <Yh9HKhESkcUIYzSr@nazgul.tnic>
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On 3/2/2022 2:30 AM, Borislav Petkov wrote:
> On Tue, Mar 01, 2022 at 11:54:48AM -0800, Jithu Joseph wrote:
>> @@ -58,6 +58,7 @@ static inline bool cpu_signatures_match(unsigned int s1, unsigned int p1,
>>  	/* ... or they intersect. */
>>  	return p1 & p2;
>>  }
>> +EXPORT_SYMBOL_GPL(cpu_signatures_match);
...
> 
> Hell, even your function signatures don't match.
> 
> And then, with that fixed it would build but then one would wonder a
> long time why that ifs thing doesn't work. Well:
> 
> # CONFIG_MICROCODE is not set

Thanks for reviewing the patch and pointing out the mistakes of not setting the module build dependency(on CONFIG_MICROCODE) and that of signature mismatch

> 
> So the proper thing to do is to extract the generic functionality for
> comparing microcode patch signatures and for gathering the information
> collect_cpu_info_early() collects, into intel-generic functions, like
> I've done with intel_get_microcode_revision(), move that functionality
> to arch/x86/kernel/cpu/intel.c and then use it *both* in the microcode
> loader *and* your driver.
> 

Will move these two function definitions from arch/x86/kernel/cpu/microcode/intel.c to arch/x86/kernel/cpu/intel.c in the next revision as you suggest above.
Need to find an appropriate header for these moved functions too.


Jithu