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Message-ID: <a7d4929b-f7ff-4ce5-800e-79df3816d9d6@amd.com>
Date: Thu, 1 May 2025 15:36:03 +0530
From: Vasant Hegde <vasant.hegde@....com>
To: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@....com>,
joro@...tes.org, suravee.suthikulpanit@....com, will@...nel.org,
robin.murphy@....com, linux-kernel@...r.kernel.org, iommu@...ts.linux.dev
Subject: Re: [PATCH v5 7/8] iommu/amd: Add debugfs support to dump IRT Table
On 4/7/2025 11:04 PM, Dheeraj Kumar Srivastava wrote:
> In cases where we have an issue in the device interrupt path with IOMMU
> interrupt remapping enabled, dumping valid IRT table entries for the device
> is very useful and good input for debugging the issue.
>
> eg.
> -> To dump irte entries for a particular device
> #echo "c4:00.0" > /sys/kernel/debug/iommu/amd/devid
> #cat /sys/kernel/debug/iommu/amd/irqtbl | less
>
> or
>
> #echo "0000:c4:00.0" > /sys/kernel/debug/iommu/amd/devid
> #cat /sys/kernel/debug/iommu/amd/irqtbl | less
>
> Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@....com>
> ---
> drivers/iommu/amd/debugfs.c | 106 ++++++++++++++++++++++++++++++++++++
> 1 file changed, 106 insertions(+)
>
> diff --git a/drivers/iommu/amd/debugfs.c b/drivers/iommu/amd/debugfs.c
> index c6ff47561afb..28fe546e0bc0 100644
> --- a/drivers/iommu/amd/debugfs.c
> +++ b/drivers/iommu/amd/debugfs.c
> @@ -11,6 +11,7 @@
> #include <linux/pci.h>
>
> #include "amd_iommu.h"
> +#include "../irq_remapping.h"
>
> static struct dentry *amd_iommu_debugfs;
>
> @@ -254,6 +255,109 @@ static int iommu_devtbl_show(struct seq_file *m, void *unused)
> }
> DEFINE_SHOW_ATTRIBUTE(iommu_devtbl);
>
> +static void dump_128_irte(struct seq_file *m, struct irq_remap_table *table, u16 int_tab_len)
> +{
> + struct irte_ga *ptr, *irte;
> + int index;
> +
> + for (index = 0; index < int_tab_len; index++) {
> + ptr = (struct irte_ga *)table->table;
> + irte = &ptr[index];
> +
> + if (AMD_IOMMU_GUEST_IR_VAPIC(amd_iommu_guest_ir) &&
> + !irte->lo.fields_vapic.valid)
> + continue;
> + else if (!irte->lo.fields_remap.valid)
> + continue;
> + seq_printf(m, "IRT[%04d] %016llx %016llx\n", index, irte->hi.val, irte->lo.val);
> + }
> +}
> +
> +static void dump_32_irte(struct seq_file *m, struct irq_remap_table *table, u16 int_tab_len)
> +{
> + union irte *ptr, *irte;
> + int index;
> +
> + for (index = 0; index < int_tab_len; index++) {
> + ptr = (union irte *)table->table;
> + irte = &ptr[index];
> +
> + if (!irte->fields.valid)
> + continue;
> + seq_printf(m, "IRT[%04d] %08x\n", index, irte->val);
> + }
> +}
> +
> +static void dump_irte(struct seq_file *m, u16 devid, struct amd_iommu_pci_seg *pci_seg)
> +{
> + struct dev_table_entry *dev_table;
> + struct irq_remap_table *table;
> + struct amd_iommu *iommu;
> + unsigned long flags;
> + u16 int_tab_len;
> +
> + table = pci_seg->irq_lookup_table[devid];
> + if (!table) {
> + seq_printf(m, "IRQ lookup table not set for %04x:%02x:%02x:%x\n",
> + pci_seg->id, PCI_BUS_NUM(devid), PCI_SLOT(devid), PCI_FUNC(devid));
> + return;
> + }
> +
> + iommu = pci_seg->rlookup_table[devid];
> + if (!iommu)
> + return;
> +
> + dev_table = get_dev_table(iommu);
> + if (!dev_table) {
> + seq_puts(m, "Device table not found");
> + return;
> + }
> +
> + int_tab_len = 1 << ((dev_table[devid].data[2] >> 1) & 0xfULL);
This is hard to read. Please use the macros like FIELD_GET
> + if (int_tab_len > 2048)
s/2048/MAX_IRQS_PER_TABLE_2K/
-Vasant
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