linux-kernel - Re: [PATCH v6 2/5] iommu/vt-d: Add debugfs support to show context internals

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Date:   Wed, 10 Jan 2018 11:02:08 -0600
From:   Gary R Hook <gary.hook@....com>
To:     Sohil Mehta <sohil.mehta@...el.com>,
        Joerg Roedel <joro@...tes.org>,
        Alex Williamson <alex.williamson@...hat.com>
Cc:     Ravi V Shankar <ravi.v.shankar@...el.com>,
        Fenghua Yu <fenghua.yu@...el.com>,
        linux-kernel@...r.kernel.org, iommu@...ts.linux-foundation.org,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Gayatri Kammela <gayatri.kammela@...el.com>
Subject: Re: [PATCH v6 2/5] iommu/vt-d: Add debugfs support to show context
 internals

On 01/09/2018 09:48 PM, Sohil Mehta wrote:
> From: Gayatri Kammela <gayatri.kammela@...el.com>
> 
> IOMMU internals states such as root and context can be exported to the
> userspace.
> 
> Example of such dump in Kabylake:
> 
> root@...-KBLH-01:~# cat
> /sys/kernel/debug/intel_iommu/dmar_translation_struct
> 
> IOMMU dmar0: Extended Root Table Addr:402b9e800
> Extended Root table entries:
> Bus 0 L: 402150001 H: 0
> Lower Context table entries for Bus: 0
> [entry] DID :B :D .F    Low             High
> [80]    0000:00:0a.00   40214fa05       102
> Higher Context table entries for Bus: 0
> [80]    0000:00:0a.00   40260000c       0
> 
> IOMMU dmar1:    Root Table Addr:4558a3000
>   Root tbl entries:
> Bus 0 L: 4558aa001 H: 0
>   Context table entries for Bus: 0
> [entry] DID :B :D .F    Low             High
> [160]   0000:00:14.00   4558a9001       102
> [184]   0000:00:17.00   400eac001       302
> [248]   0000:00:1f.00   4558af001       202
> [251]   0000:00:1f.03   40070e001       502
> [254]   0000:00:1f.06   4467c9001       602
>   Root tbl entries:
> Bus 1 L: 3fc8c2001 H: 0
>   Context table entries for Bus: 1
> [entry] DID :B :D .F    Low             High
> [0]     0000:01:00.00   3fc8c3001       402
> 
> Cc: Sohil Mehta <sohil.mehta@...el.com>
> Cc: Fenghua Yu <fenghua.yu@...el.com>
> Cc: Ashok Raj <ashok.raj@...el.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
> Signed-off-by: Gayatri Kammela <gayatri.kammela@...el.com>
> ---
> 
> v6: Change the order of includes to an alphabetical order
>      Change seq_printf formatting
> 
> v5: Change to a SPDX license tag
>      Fix seq_printf formatting
> 
> v4: Remove the unused function parameter
>      Fix checkpatch.pl warnings
>      Remove error reporting for debugfs_create_file function
>      Fix unnecessary reprogramming of the context entries
>      Simplify and merge the show context and extended context patch into one
>      Remove redundant IOMMU null check under for_each_active_iommu
> 
> v3: Add a macro for seq file operations
>      Change the intel_iommu_ctx file name to dmar_translation_struct
> 
> v2: No change
> 
>   drivers/iommu/Makefile            |   1 +
>   drivers/iommu/intel-iommu-debug.c | 139 ++++++++++++++++++++++++++++++++++++++
>   drivers/iommu/intel-iommu.c       |   4 ++
>   3 files changed, 144 insertions(+)
>   create mode 100644 drivers/iommu/intel-iommu-debug.c
> 
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 1fb6958..fdbaf46 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -15,6 +15,7 @@ obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
>   obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
>   obj-$(CONFIG_DMAR_TABLE) += dmar.o
>   obj-$(CONFIG_INTEL_IOMMU) += intel-iommu.o
> +obj-$(CONFIG_INTEL_IOMMU_DEBUG) += intel-iommu-debug.o
>   obj-$(CONFIG_INTEL_IOMMU_SVM) += intel-svm.o
>   obj-$(CONFIG_IPMMU_VMSA) += ipmmu-vmsa.o
>   obj-$(CONFIG_IRQ_REMAP) += intel_irq_remapping.o irq_remapping.o
> diff --git a/drivers/iommu/intel-iommu-debug.c b/drivers/iommu/intel-iommu-debug.c
> new file mode 100644
> index 0000000..d5b0eea
> --- /dev/null
> +++ b/drivers/iommu/intel-iommu-debug.c
> @@ -0,0 +1,139 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright © 2017 Intel Corporation.
> + *
> + * Authors: Gayatri Kammela <gayatri.kammela@...el.com>
> + *          Jacob Pan <jacob.jun.pan@...ux.intel.com>
> + *
> + */
> +
> +#define pr_fmt(fmt)     "INTEL_IOMMU: " fmt
> +#include <linux/debugfs.h>
> +#include <linux/dmar.h>
> +#include <linux/err.h>
> +#include <linux/intel-iommu.h>
> +#include <linux/intel-svm.h>
> +#include <linux/io.h>
> +#include <linux/iommu.h>
> +#include <linux/pci.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +#include <linux/uaccess.h>
> +
> +#include "irq_remapping.h"
> +
> +#define TOTAL_BUS_NR (256) /* full bus range 256 */
> +#define DEFINE_SHOW_ATTRIBUTE(__name)					\
> +static int __name ## _open(struct inode *inode, struct file *file)	\
> +{									\
> +	return single_open(file, __name ## _show, inode->i_private);	\
> +}									\
> +static const struct file_operations __name ## _fops =			\
> +{									\
> +	.open		= __name ## _open,				\
> +	.read		= seq_read,					\
> +	.llseek		= seq_lseek,					\
> +	.release	= single_release,				\
> +	.owner		= THIS_MODULE,					\
> +}
> +
> +static void ctx_tbl_entry_show(struct seq_file *m, struct intel_iommu *iommu,
> +			       int bus, bool ext, bool new_ext)
> +{
> +	struct context_entry *context;
> +	int ctx;
> +	unsigned long flags;
> +
> +	seq_printf(m, "%s Context table entries for Bus: %d\n",
> +		   ext ? "Lower" : "", bus);
> +	seq_puts(m, "[entry]\tDID :B :D .F\tLow\t\tHigh\n");
> +
> +	spin_lock_irqsave(&iommu->lock, flags);
> +
> +	/* Publish either context entries or extended contenxt entries */

                                                       ^^^^^^^^ typo