linux-kernel - Re: [PATCH 1/2] IOMMU/AMD: Adding IOMMU PC resource management

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Message-ID: <51924C21.3020906@amd.com>
Date:	Tue, 14 May 2013 09:37:21 -0500
From:	Suravee Suthikulanit <suravee.suthikulpanit@....com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	<steven.kinney@....com>, <linux-kernel@...r.kernel.org>,
	<mingo@...hat.com>, <iommu@...ts.linux-foundation.org>,
	<joro@...tes.org>
Subject: Re: [PATCH 1/2] IOMMU/AMD: Adding IOMMU PC resource management

On 5/14/2013 2:09 AM, Peter Zijlstra wrote:
> On Mon, May 13, 2013 at 04:43:44PM -0500, steven.kinney@....com wrote:
>> +static void init_iommu_perf_ctr(struct amd_iommu *iommu)
>> +{
>> +	u32 val = 0xabcd, val2 = 0;
>> +
>> +	if (!iommu_feature(iommu, FEATURE_PC))
>> +		return;
>> +
>> +	amd_iommu_pc_present = true;
>> +
>> +	/* Check if the performance counters can be written to */
>> +	if ((0 != amd_iommu_pc_get_set_reg_val(0, 0, 0, 0, &val, true)) ||
>> +	    (0 != amd_iommu_pc_get_set_reg_val(0, 0, 0, 0, &val2, false)) ||
>> +	    (val != val2)) {
>> +		pr_err("AMD-Vi: Unable to write to IOMMU perf counter.\n");
> Would it make sense to clear amd_iommu_pc_present here?
Yes, I'll take care of this here.

Thank you,

Surave

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