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[PATCH v5 7/8] iommu/amd: Add debugfs support to dump IRT Table

Dheeraj Kumar Srivastava posted 8 patches 10 months, 1 week ago
There is a newer version of this series
[PATCH v5 7/8] iommu/amd: Add debugfs support to dump IRT Table
Posted by Dheeraj Kumar Srivastava 10 months, 1 week ago 
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@amd.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);
+	if (int_tab_len > 2048)
+		return;
+
+	seq_printf(m, "DeviceId %04x:%02x:%02x:%x\n", pci_seg->id, PCI_BUS_NUM(devid),
+		   PCI_SLOT(devid), PCI_FUNC(devid));
+
+	raw_spin_lock_irqsave(&table->lock, flags);
+	if (AMD_IOMMU_GUEST_IR_GA(amd_iommu_guest_ir))
+		dump_128_irte(m, table, int_tab_len);
+	else
+		dump_32_irte(m, table, int_tab_len);
+	seq_puts(m, "\n");
+	raw_spin_unlock_irqrestore(&table->lock, flags);
+}
+
+static int iommu_irqtbl_show(struct seq_file *m, void *unused)
+{
+	struct amd_iommu_pci_seg *pci_seg;
+	u16 devid, seg;
+
+	if (!irq_remapping_enabled) {
+		seq_puts(m, "Interrupt remapping is disabled\n");
+		return 0;
+	}
+
+	if (sbdf < 0) {
+		seq_puts(m, "Please provide valid device id input\n");
+		return 0;
+	}
+
+	seg = PCI_SBDF_TO_SEGID(sbdf);
+	devid = PCI_SBDF_TO_DEVID(sbdf);
+
+	for_each_pci_segment(pci_seg) {
+		if (pci_seg->id != seg)
+			continue;
+		dump_irte(m, devid, pci_seg);
+		break;
+	}
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(iommu_irqtbl);
+
 void amd_iommu_debugfs_setup(void)
 {
 	struct amd_iommu *iommu;
@@ -280,4 +384,6 @@ void amd_iommu_debugfs_setup(void)
 			    &devid_fops);
 	debugfs_create_file("devtbl", 0444, amd_iommu_debugfs, NULL,
 			    &iommu_devtbl_fops);
+	debugfs_create_file("irqtbl", 0444, amd_iommu_debugfs, NULL,
+			    &iommu_irqtbl_fops);
 }
-- 
2.25.1
Re: [PATCH v5 7/8] iommu/amd: Add debugfs support to dump IRT Table
Posted by Vasant Hegde 9 months, 1 week ago 

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@amd.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
Re: [PATCH v5 7/8] iommu/amd: Add debugfs support to dump IRT Table
Posted by Dheeraj Kumar Srivastava 8 months, 1 week ago 
Hi Vasant,

Thanks for reviewing the patch.

On 5/1/2025 3:36 PM, Vasant Hegde wrote:
> 
> 
> 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@amd.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/

Sure I will use macros to fetch and validate IRT table length from DTE.

Thanks
Dheeraj

> 
> 
> -Vasant
> 
>

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