RE: [PATCH v4 2/5] iommu/vt-d: debugfs: Add support to show inv queue internals

[Tian, Kevin]

> From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Sent: Thursday, May 7, 2020 8:56 AM
> 
> Export invalidation queue internals of each iommu device through the
> debugfs.
> 
> Example of such dump on a Skylake machine:
> 
> $ sudo cat /sys/kernel/debug/iommu/intel/invalidation_queue
> Invalidation queue on IOMMU: dmar1
>  Base: 0x1672c9000      Head: 80        Tail: 80
> Index           qw0                     qw1                     status
>     0   0000000000000004        0000000000000000        0000000000000000
>     1   0000000200000025        00000001672be804        0000000000000000
>     2   0000000000000011        0000000000000000        0000000000000000
>     3   0000000200000025        00000001672be80c        0000000000000000
>     4   00000000000000d2        0000000000000000        0000000000000000
>     5   0000000200000025        00000001672be814        0000000000000000
>     6   0000000000000014        0000000000000000        0000000000000000
>     7   0000000200000025        00000001672be81c        0000000000000000
>     8   0000000000000014        0000000000000000        0000000000000000
>     9   0000000200000025        00000001672be824        0000000000000000
> 
> Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> ---
>  drivers/iommu/intel-iommu-debugfs.c | 62
> +++++++++++++++++++++++++++++
>  1 file changed, 62 insertions(+)
> 
> diff --git a/drivers/iommu/intel-iommu-debugfs.c b/drivers/iommu/intel-
> iommu-debugfs.c
> index 3eb1fe240fb0..e3089865b8f3 100644
> --- a/drivers/iommu/intel-iommu-debugfs.c
> +++ b/drivers/iommu/intel-iommu-debugfs.c
> @@ -372,6 +372,66 @@ static int domain_translation_struct_show(struct
> seq_file *m, void *unused)
>  }
>  DEFINE_SHOW_ATTRIBUTE(domain_translation_struct);
> 
> +static void invalidation_queue_entry_show(struct seq_file *m,
> +					  struct intel_iommu *iommu)
> +{
> +	int index, shift = qi_shift(iommu);
> +	struct qi_desc *desc;
> +	int offset;
> +
> +	if (ecap_smts(iommu->ecap))
> +		seq_puts(m,
> "Index\t\tqw0\t\t\tqw1\t\t\tqw2\t\t\tqw3\t\t\tstatus\n");
> +	else
> +		seq_puts(m, "Index\t\tqw0\t\t\tqw1\t\t\tstatus\n");
> +
> +	for (index = 0; index < QI_LENGTH; index++) {
> +		offset = index << shift;
> +		desc = iommu->qi->desc + offset;
> +		if (ecap_smts(iommu->ecap))
> +			seq_printf(m,
> "%5d\t%016llx\t%016llx\t%016llx\t%016llx\t%016x\n",
> +				   index, desc->qw0, desc->qw1,
> +				   desc->qw2, desc->qw3,
> +				   iommu->qi->desc_status[index]);
> +		else
> +			seq_printf(m, "%5d\t%016llx\t%016llx\t%016x\n",
> +				   index, desc->qw0, desc->qw1,
> +				   iommu->qi->desc_status[index]);
> +	}
> +}
> +
> +static int invalidation_queue_show(struct seq_file *m, void *unused)
> +{
> +	struct dmar_drhd_unit *drhd;
> +	struct intel_iommu *iommu;
> +	unsigned long flags;
> +	struct q_inval *qi;
> +	int shift;
> +
> +	rcu_read_lock();
> +	for_each_active_iommu(iommu, drhd) {
> +		qi = iommu->qi;
> +		shift = qi_shift(iommu);
> +
> +		if (!qi || !ecap_qis(iommu->ecap))
> +			continue;
> +
> +		seq_printf(m, "Invalidation queue on IOMMU: %s\n",
> iommu->name);
> +
> +		raw_spin_lock_irqsave(&qi->q_lock, flags);
> +		seq_printf(m, " Base: 0x%llx\tHead: %lld\tTail: %lld\n",
> +			   virt_to_phys(qi->desc),
> +			   dmar_readq(iommu->reg + DMAR_IQH_REG) >>
> shift,
> +			   dmar_readq(iommu->reg + DMAR_IQT_REG) >>
> shift);
> +		invalidation_queue_entry_show(m, iommu);
> +		raw_spin_unlock_irqrestore(&qi->q_lock, flags);
> +		seq_putc(m, '\n');
> +	}
> +	rcu_read_unlock();
> +
> +	return 0;
> +}
> +DEFINE_SHOW_ATTRIBUTE(invalidation_queue);
> +
>  #ifdef CONFIG_IRQ_REMAP
>  static void ir_tbl_remap_entry_show(struct seq_file *m,
>  				    struct intel_iommu *iommu)
> @@ -490,6 +550,8 @@ void __init intel_iommu_debugfs_init(void)
>  	debugfs_create_file("domain_translation_struct", 0444,
>  			    intel_iommu_debug, NULL,
>  			    &domain_translation_struct_fops);
> +	debugfs_create_file("invalidation_queue", 0444, intel_iommu_debug,
> +			    NULL, &invalidation_queue_fops);
>  #ifdef CONFIG_IRQ_REMAP
>  	debugfs_create_file("ir_translation_struct", 0444,
> intel_iommu_debug,
>  			    NULL, &ir_translation_struct_fops);
> --
> 2.17.1

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>