linux-kernel - Re: [PATCH 2/2] apic, x86: Use BIOS settings for IBS and MCE threshold interrupt LVT offsets

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Message-ID: <20101008092452.GE13563@erda.amd.com>
Date:	Fri, 8 Oct 2010 11:24:52 +0200
From:	Robert Richter <robert.richter@....com>
To:	Cyrill Gorcunov <gorcunov@...il.com>
CC:	Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] apic, x86: Use BIOS settings for IBS and MCE
 threshold interrupt LVT offsets

On 06.10.10 15:41:50, Cyrill Gorcunov wrote:
> On Wed, Oct 06, 2010 at 12:27:54PM +0200, Robert Richter wrote:
> > We want the BIOS to setup the EILVT APIC registers. The offsets were
> > hardcoded and BIOS settings were overwritten by the OS. Now, the
> > subsystems for MCE threshold and IBS determine the LVT offset from the
> > registers the BIOS has setup. If the BIOS setup is buggy on a family
> > 10h system, a workaround enables IBS. If the OS determines an invalid
> > register setup, a "[Firmware Bug]: " error message is reported.
> > 
> > We need this change also for upcomming cpu families.
> > 
> > Signed-off-by: Robert Richter <robert.richter@....com>
> > ---
> 
> Hi Robert, a few comments
> 
> ...  
> >  /*
> >   * Program the next event, relative to now
> > diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> > index 5e97529..e13d4bd 100644
> > --- a/arch/x86/kernel/cpu/mcheck/mce_amd.c
> > +++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c
> > @@ -131,7 +131,8 @@ void mce_amd_feature_init(struct cpuinfo_x86 *c)
> >  	u32 low = 0, high = 0, address = 0;
> >  	unsigned int bank, block;
> >  	struct thresh_restart tr;
> > -	u8 lvt_off;
> > +	int lvt_off = -1;
> > +	u8 offset;
> >  
> >  	for (bank = 0; bank < NR_BANKS; ++bank) {
> >  		for (block = 0; block < NR_BLOCKS; ++block) {
> > @@ -165,8 +166,28 @@ void mce_amd_feature_init(struct cpuinfo_x86 *c)
> >  			if (shared_bank[bank] && c->cpu_core_id)
> >  				break;
> >  #endif
> > -			lvt_off = setup_APIC_eilvt_mce(THRESHOLD_APIC_VECTOR,
> > -						       APIC_EILVT_MSG_FIX, 0);
> > +			offset = (high & MASK_LVTOFF_HI) >> 20;
> > +			if (lvt_off < 0) {
> > +				if (setup_APIC_eilvt(offset,
> > +						     THRESHOLD_APIC_VECTOR,
> > +						     APIC_EILVT_MSG_FIX, 0)) {
> > +					pr_err(FW_BUG "cpu %d, failed to "
> > +					       "setup threshold interrupt "
> > +					       "for bank %d, block %d "
> > +					       "(MSR%08X=0x%x%08x)",
> > +					       smp_processor_id(), bank, block,
> > +					       address, high, low);
> > +					continue;
> > +				}
> > +				lvt_off = offset;
> > +			} else if (lvt_off != offset) {
> 
> Could we put explicit type specificator here? For better readbility.
> ...

Cyrill,

Do you mean an explicit type cast here, or something else?

> 
> > +static int force_ibs_eilvt_setup(void)
> > +{
> > +	int i;
> > +	int ret;
> > +
> > +	/* find the next free available EILVT entry */
> > +	for (i = 1; i < 4; i++) {
> 
> APIC_EILVT_NR_MAX here, no?

Yes, will update this if a -v2 patch set will be necessary.

Thanks for review,

-Robert

> 
> > +		if (!eilvt_is_available(i))
> > +			continue;
> > +		ret = setup_ibs_ctl(i);
> > +		if (ret)
> > +			return ret;
> > +		return 0;
> >  	}
> >  
>  
>   Cyrill
> 

-- 
Advanced Micro Devices, Inc.
Operating System Research Center

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