[PATCH 0/2] iommu: MSI parent domain conversion

[PATCH 0/2] iommu: MSI parent domain conversion

[Nam Cao]

The initial implementation of PCI/MSI interrupt domains in the hierarchical
interrupt domain model used a shortcut by providing a global PCI/MSI
domain.

This works because the PCI/MSI[X] hardware is standardized and uniform, but
it violates the basic design principle of hierarchical interrupt domains:
Each hardware block involved in the interrupt delivery chain should have a
separate interrupt domain.

For PCI/MSI[X], the interrupt controller is per PCI device and not a global
made-up entity.

Unsurprisingly, the shortcut turned out to have downsides as it does not
allow dynamic allocation of interrupt vectors after initialization and it
prevents supporting IMS on PCI. For further details, see:

https://lore.kernel.org/lkml/20221111120501.026511281@linutronix.de/

The solution is implementing per device MSI domains, this means the
entities which provide global PCI/MSI domain so far have to implement MSI
parent domain functionality instead.

This series convert the IOMMU drivers to implement MSI parent domain.

 drivers/iommu/Kconfig               |  1 +
 drivers/iommu/amd/Kconfig           |  1 +
 drivers/iommu/amd/iommu.c           | 26 ++++++++++++++------------
 drivers/iommu/intel/irq_remapping.c | 28 ++++++++++++++--------------
 4 files changed, 30 insertions(+), 26 deletions(-)

-- 
2.39.5

[PATCH 1/2] iommu/amd: Convert to msi_create_parent_irq_domain() helper

[Nam Cao]

From: Marc Zyngier <maz@kernel.org>

Now that we have a concise helper to create an MSI parent domain,
switch the AMD IOMMU remapping over to that.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Nam Cao <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241204124549.607054-9-maz@kernel.org
---
 drivers/iommu/amd/Kconfig |  1 +
 drivers/iommu/amd/iommu.c | 26 ++++++++++++++------------
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/drivers/iommu/amd/Kconfig b/drivers/iommu/amd/Kconfig
index 994063e5586f0..ecef69c11144d 100644
--- a/drivers/iommu/amd/Kconfig
+++ b/drivers/iommu/amd/Kconfig
@@ -7,6 +7,7 @@ config AMD_IOMMU
 	select PCI_ATS
 	select PCI_PRI
 	select PCI_PASID
+	select IRQ_MSI_LIB
 	select MMU_NOTIFIER
 	select IOMMU_API
 	select IOMMU_IOVA
diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c
index 3117d99cf83d0..0cb7c077d388f 100644
--- a/drivers/iommu/amd/iommu.c
+++ b/drivers/iommu/amd/iommu.c
@@ -25,6 +25,7 @@
 #include <linux/notifier.h>
 #include <linux/export.h>
 #include <linux/irq.h>
+#include <linux/irqchip/irq-msi-lib.h>
 #include <linux/msi.h>
 #include <linux/irqdomain.h>
 #include <linux/percpu.h>
@@ -3970,29 +3971,30 @@ static struct irq_chip amd_ir_chip = {
 
 static const struct msi_parent_ops amdvi_msi_parent_ops = {
 	.supported_flags	= X86_VECTOR_MSI_FLAGS_SUPPORTED | MSI_FLAG_MULTI_PCI_MSI,
+	.bus_select_token	= DOMAIN_BUS_AMDVI,
+	.bus_select_mask	= MATCH_PCI_MSI,
 	.prefix			= "IR-",
 	.init_dev_msi_info	= msi_parent_init_dev_msi_info,
 };
 
 int amd_iommu_create_irq_domain(struct amd_iommu *iommu)
 {
-	struct fwnode_handle *fn;
+	struct irq_domain_info info = {
+		.fwnode		= irq_domain_alloc_named_id_fwnode("AMD-IR", iommu->index),
+		.ops		= &amd_ir_domain_ops,
+		.domain_flags	= IRQ_DOMAIN_FLAG_ISOLATED_MSI,
+		.host_data	= iommu,
+		.parent		= arch_get_ir_parent_domain(),
+	};
 
-	fn = irq_domain_alloc_named_id_fwnode("AMD-IR", iommu->index);
-	if (!fn)
+	if (!info.fwnode)
 		return -ENOMEM;
-	iommu->ir_domain = irq_domain_create_hierarchy(arch_get_ir_parent_domain(), 0, 0,
-						       fn, &amd_ir_domain_ops, iommu);
+
+	iommu->ir_domain = msi_create_parent_irq_domain(&info, &amdvi_msi_parent_ops);
 	if (!iommu->ir_domain) {
-		irq_domain_free_fwnode(fn);
+		irq_domain_free_fwnode(info.fwnode);
 		return -ENOMEM;
 	}
-
-	irq_domain_update_bus_token(iommu->ir_domain,  DOMAIN_BUS_AMDVI);
-	iommu->ir_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT |
-				   IRQ_DOMAIN_FLAG_ISOLATED_MSI;
-	iommu->ir_domain->msi_parent_ops = &amdvi_msi_parent_ops;
-
 	return 0;
 }
 
-- 
2.39.5

[PATCH 2/2] iommu/intel: Convert to msi_create_parent_irq_domain() helper

[Nam Cao]

From: Marc Zyngier <maz@kernel.org>

Now that we have a concise helper to create an MSI parent domain,
switch the Intel IOMMU remapping over to that.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Nam Cao <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241204124549.607054-10-maz@kernel.org
---
 drivers/iommu/Kconfig               |  1 +
 drivers/iommu/intel/irq_remapping.c | 28 ++++++++++++++--------------
 2 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
index 0a33d995d15dd..c5ce712a37b9f 100644
--- a/drivers/iommu/Kconfig
+++ b/drivers/iommu/Kconfig
@@ -200,6 +200,7 @@ source "drivers/iommu/riscv/Kconfig"
 config IRQ_REMAP
 	bool "Support for Interrupt Remapping"
 	depends on X86_64 && X86_IO_APIC && PCI_MSI && ACPI
+	select IRQ_MSI_LIB
 	help
 	  Supports Interrupt remapping for IO-APIC and MSI devices.
 	  To use x2apic mode in the CPU's which support x2APIC enhancements or
diff --git a/drivers/iommu/intel/irq_remapping.c b/drivers/iommu/intel/irq_remapping.c
index cf7b6882ec755..2ef71ba696b1f 100644
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -10,6 +10,7 @@
 #include <linux/hpet.h>
 #include <linux/pci.h>
 #include <linux/irq.h>
+#include <linux/irqchip/irq-msi-lib.h>
 #include <linux/acpi.h>
 #include <linux/irqdomain.h>
 #include <linux/crash_dump.h>
@@ -518,8 +519,14 @@ static void iommu_enable_irq_remapping(struct intel_iommu *iommu)
 
 static int intel_setup_irq_remapping(struct intel_iommu *iommu)
 {
+	struct irq_domain_info info = {
+		.ops		= &intel_ir_domain_ops,
+		.parent		= arch_get_ir_parent_domain(),
+		.domain_flags	= IRQ_DOMAIN_FLAG_ISOLATED_MSI,
+		.size		= INTR_REMAP_TABLE_ENTRIES,
+		.host_data	= iommu,
+	};
 	struct ir_table *ir_table;
-	struct fwnode_handle *fn;
 	unsigned long *bitmap;
 	void *ir_table_base;
 
@@ -544,25 +551,16 @@ static int intel_setup_irq_remapping(struct intel_iommu *iommu)
 		goto out_free_pages;
 	}
 
-	fn = irq_domain_alloc_named_id_fwnode("INTEL-IR", iommu->seq_id);
-	if (!fn)
+	info.fwnode = irq_domain_alloc_named_id_fwnode("INTEL-IR", iommu->seq_id);
+	if (!info.fwnode)
 		goto out_free_bitmap;
 
-	iommu->ir_domain =
-		irq_domain_create_hierarchy(arch_get_ir_parent_domain(),
-					    0, INTR_REMAP_TABLE_ENTRIES,
-					    fn, &intel_ir_domain_ops,
-					    iommu);
+	iommu->ir_domain = msi_create_parent_irq_domain(&info, &dmar_msi_parent_ops);
 	if (!iommu->ir_domain) {
 		pr_err("IR%d: failed to allocate irqdomain\n", iommu->seq_id);
 		goto out_free_fwnode;
 	}
 
-	irq_domain_update_bus_token(iommu->ir_domain,  DOMAIN_BUS_DMAR);
-	iommu->ir_domain->flags |= IRQ_DOMAIN_FLAG_MSI_PARENT |
-				   IRQ_DOMAIN_FLAG_ISOLATED_MSI;
-	iommu->ir_domain->msi_parent_ops = &dmar_msi_parent_ops;
-
 	ir_table->base = ir_table_base;
 	ir_table->bitmap = bitmap;
 	iommu->ir_table = ir_table;
@@ -608,7 +606,7 @@ static int intel_setup_irq_remapping(struct intel_iommu *iommu)
 	irq_domain_remove(iommu->ir_domain);
 	iommu->ir_domain = NULL;
 out_free_fwnode:
-	irq_domain_free_fwnode(fn);
+	irq_domain_free_fwnode(info.fwnode);
 out_free_bitmap:
 	bitmap_free(bitmap);
 out_free_pages:
@@ -1530,6 +1528,8 @@ static const struct irq_domain_ops intel_ir_domain_ops = {
 
 static const struct msi_parent_ops dmar_msi_parent_ops = {
 	.supported_flags	= X86_VECTOR_MSI_FLAGS_SUPPORTED | MSI_FLAG_MULTI_PCI_MSI,
+	.bus_select_token	= DOMAIN_BUS_DMAR,
+	.bus_select_mask	= MATCH_PCI_MSI,
 	.prefix			= "IR-",
 	.init_dev_msi_info	= msi_parent_init_dev_msi_info,
 };
-- 
2.39.5