@@ -15,6 +15,7 @@
#include <linux/mutex.h>
#include <linux/pci.h>
#include <linux/slab.h>
+#include <linux/seq_file.h>
#include <linux/sysfs.h>
#include <linux/types.h>
#include <linux/xarray.h>
@@ -756,12 +757,30 @@ static int msi_domain_translate(struct irq_domain *domain, struct irq_fwspec *fw
return info->ops->msi_translate(domain, fwspec, hwirq, type);
}
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+static void msi_domain_debug_show(struct seq_file *m, struct irq_domain *d,
+ struct irq_data *irqd, int ind)
+{
+ struct msi_desc *desc = irq_get_msi_desc(irqd->irq);
+
+ if (!desc)
+ return;
+
+ seq_printf(m, "\n%*saddress_hi: 0x%08x", ind + 1, "", desc->msg.address_hi);
+ seq_printf(m, "\n%*saddress_lo: 0x%08x", ind + 1, "", desc->msg.address_lo);
+ seq_printf(m, "\n%*smsg_data: 0x%08x\n", ind + 1, "", desc->msg.data);
+}
+#endif
+
static const struct irq_domain_ops msi_domain_ops = {
.alloc = msi_domain_alloc,
.free = msi_domain_free,
.activate = msi_domain_activate,
.deactivate = msi_domain_deactivate,
.translate = msi_domain_translate,
+#ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+ .debug_show = msi_domain_debug_show,
+#endif
};
static irq_hw_number_t msi_domain_ops_get_hwirq(struct msi_domain_info *info,
The debug_show() callback function is implemented in the MSI core code. And assign it to the domain ops::debug_show() creation. When debugging MSI-related hardware issues (e.g., interrupt delivery failures), developers currently need to either: 1. Recompile kernel with dynamic debug for tracing msi_desc. 2. Manually read device registers through low-level tools. Both approaches become challenging in production environments where dynamic debugging is often disabled. This patch proposes to expose MSI address_hi/address_lo and msg_data in `/sys/kernel/debug/irq/irqs/<msi_irq_num>`. These fields are critical to: - Verify if MSI configuration matches hardware programming - Diagnose interrupt routing errors (e.g., mismatched destination ID) - Validate remapping behavior in virtualized environments The information is already maintained in msi_desc and irq_data structures. By surfacing it through debugfs: - We create a unified place for runtime IRQ diagnostics - Enable debugging without kernel rebuilds or special tools - Align with existing exposure of IRQ chip/type/affinity data Sample output: address_hi: 0x00000000 address_lo: 0xfe670040 msg_data: 0x00000001 Signed-off-by: Hans Zhang <18255117159@163.com> --- Changes since v2-v3: https://lore.kernel.org/linux-pci/20250301123953.291675-1-18255117159@163.com/ https://lore.kernel.org/linux-pci/20250302020328.296523-1-18255117159@163.com/ - Fix implicit declaration of function 'seq_printf'. - Fix 'const struct irq_domain_ops' has no member named 'debug_show'. - The patch commit message were modified. - Removes the display that is not currently an MSI/MSIX interrupt. Changes since v1: https://lore.kernel.org/linux-pci/20250227162821.253020-1-18255117159@163.com/ - According to Thomas(tglx), the debug_show() callback should be added to the MSI core code. --- kernel/irq/msi.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) base-commit: 76544811c850a1f4c055aa182b513b7a843868ea