Move away from the legacy MSI domain setup, switch to use
msi_create_parent_irq_domain().

While doing the conversion, I noticed that hv_irq_compose_msi_msg() is
doing more than it is supposed to (composing message content). The
interrupt allocation bits should be moved into hv_msi_domain_alloc().
However, I have no hardware to test this change, therefore I leave a TODO
note.

Signed-off-by: Nam Cao <nam...@linutronix.de>
---
 arch/x86/hyperv/irqdomain.c | 111 ++++++++++++++++++++++++------------
 drivers/hv/Kconfig          |   1 +
 2 files changed, 77 insertions(+), 35 deletions(-)

diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index 090f5ac9f492..c3ba12b1bc07 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -11,6 +11,7 @@
 #include <linux/pci.h>
 #include <linux/irq.h>
 #include <linux/export.h>
+#include <linux/irqchip/irq-msi-lib.h>
 #include <asm/mshyperv.h>
 
 static int hv_map_interrupt(union hv_device_id device_id, bool level,
@@ -289,59 +290,99 @@ static void hv_teardown_msi_irq(struct pci_dev *dev, 
struct irq_data *irqd)
        (void)hv_unmap_msi_interrupt(dev, &old_entry);
 }
 
-static void hv_msi_free_irq(struct irq_domain *domain,
-                           struct msi_domain_info *info, unsigned int virq)
-{
-       struct irq_data *irqd = irq_get_irq_data(virq);
-       struct msi_desc *desc;
-
-       if (!irqd)
-               return;
-
-       desc = irq_data_get_msi_desc(irqd);
-       if (!desc || !desc->irq || WARN_ON_ONCE(!dev_is_pci(desc->dev)))
-               return;
-
-       hv_teardown_msi_irq(to_pci_dev(desc->dev), irqd);
-}
-
 /*
  * IRQ Chip for MSI PCI/PCI-X/PCI-Express Devices,
  * which implement the MSI or MSI-X Capability Structure.
  */
 static struct irq_chip hv_pci_msi_controller = {
        .name                   = "HV-PCI-MSI",
-       .irq_unmask             = pci_msi_unmask_irq,
-       .irq_mask               = pci_msi_mask_irq,
        .irq_ack                = irq_chip_ack_parent,
-       .irq_retrigger          = irq_chip_retrigger_hierarchy,
        .irq_compose_msi_msg    = hv_irq_compose_msi_msg,
-       .irq_set_affinity       = msi_domain_set_affinity,
-       .flags                  = IRQCHIP_SKIP_SET_WAKE | IRQCHIP_MOVE_DEFERRED,
+       .irq_set_affinity       = irq_chip_set_affinity_parent,
 };
 
-static struct msi_domain_ops pci_msi_domain_ops = {
-       .msi_free               = hv_msi_free_irq,
-       .msi_prepare            = pci_msi_prepare,
+static bool hv_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
+                                struct irq_domain *real_parent, struct 
msi_domain_info *info)
+{
+       struct irq_chip *chip = info->chip;
+
+       if (!msi_lib_init_dev_msi_info(dev, domain, real_parent, info))
+               return false;
+
+       chip->flags |= IRQCHIP_SKIP_SET_WAKE | IRQCHIP_MOVE_DEFERRED;
+
+       info->ops->msi_prepare = pci_msi_prepare;
+
+       return true;
+}
+
+#define HV_MSI_FLAGS_SUPPORTED (MSI_GENERIC_FLAGS_MASK | MSI_FLAG_PCI_MSIX)
+#define HV_MSI_FLAGS_REQUIRED  (MSI_FLAG_USE_DEF_DOM_OPS | 
MSI_FLAG_USE_DEF_CHIP_OPS)
+
+static struct msi_parent_ops hv_msi_parent_ops = {
+       .supported_flags        = HV_MSI_FLAGS_SUPPORTED,
+       .required_flags         = HV_MSI_FLAGS_REQUIRED,
+       .bus_select_token       = DOMAIN_BUS_NEXUS,
+       .bus_select_mask        = MATCH_PCI_MSI,
+       .chip_flags             = MSI_CHIP_FLAG_SET_ACK,
+       .prefix                 = "HV-",
+       .init_dev_msi_info      = hv_init_dev_msi_info,
 };
 
-static struct msi_domain_info hv_pci_msi_domain_info = {
-       .flags          = MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
-                         MSI_FLAG_PCI_MSIX,
-       .ops            = &pci_msi_domain_ops,
-       .chip           = &hv_pci_msi_controller,
-       .handler        = handle_edge_irq,
-       .handler_name   = "edge",
+static int hv_msi_domain_alloc(struct irq_domain *d, unsigned int virq, 
unsigned int nr_irqs,
+                              void *arg)
+{
+       /*
+        * TODO: The allocation bits of hv_irq_compose_msi_msg(), i.e. 
everything except
+        * entry_to_msi_msg() should be in here.
+        */
+
+       int ret;
+
+       ret = irq_domain_alloc_irqs_parent(d, virq, nr_irqs, arg);
+       if (ret)
+               return ret;
+
+       for (int i = 0; i < nr_irqs; ++i) {
+               irq_domain_set_info(d, virq + i, 0, &hv_pci_msi_controller, 
NULL,
+                                   handle_edge_irq, NULL, "edge");
+       }
+       return 0;
+}
+
+static void hv_msi_domain_free(struct irq_domain *d, unsigned int virq, 
unsigned int nr_irqs)
+{
+       for (int i = 0; i < nr_irqs; ++i) {
+               struct irq_data *irqd = irq_domain_get_irq_data(d, virq);
+               struct msi_desc *desc;
+
+               desc = irq_data_get_msi_desc(irqd);
+               if (!desc || !desc->irq || WARN_ON_ONCE(!dev_is_pci(desc->dev)))
+                       continue;
+
+               hv_teardown_msi_irq(to_pci_dev(desc->dev), irqd);
+       }
+       irq_domain_free_irqs_top(d, virq, nr_irqs);
+}
+
+static const struct irq_domain_ops hv_msi_domain_ops = {
+       .select = msi_lib_irq_domain_select,
+       .alloc  = hv_msi_domain_alloc,
+       .free   = hv_msi_domain_free,
 };
 
 struct irq_domain * __init hv_create_pci_msi_domain(void)
 {
        struct irq_domain *d = NULL;
-       struct fwnode_handle *fn;
 
-       fn = irq_domain_alloc_named_fwnode("HV-PCI-MSI");
-       if (fn)
-               d = pci_msi_create_irq_domain(fn, &hv_pci_msi_domain_info, 
x86_vector_domain);
+       struct irq_domain_info info = {
+               .fwnode         = irq_domain_alloc_named_fwnode("HV-PCI-MSI"),
+               .ops            = &hv_msi_domain_ops,
+               .parent         = x86_vector_domain,
+       };
+
+       if (info.fwnode)
+               d = msi_create_parent_irq_domain(&info, &hv_msi_parent_ops);
 
        /* No point in going further if we can't get an irq domain */
        BUG_ON(!d);
diff --git a/drivers/hv/Kconfig b/drivers/hv/Kconfig
index 57623ca7f350..9afffedce290 100644
--- a/drivers/hv/Kconfig
+++ b/drivers/hv/Kconfig
@@ -10,6 +10,7 @@ config HYPERV
        select X86_HV_CALLBACK_VECTOR if X86
        select OF_EARLY_FLATTREE if OF
        select SYSFB if EFI && !HYPERV_VTL_MODE
+       select IRQ_MSI_LIB if X86
        help
          Select this option to run Linux as a Hyper-V client operating
          system.
-- 
2.49.0


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