On Tue, Nov 10 2020 at 18:50, Thomas Gleixner wrote:
> On Tue, Nov 10 2020 at 16:33, David Woodhouse wrote:
>> If I could get post-5.5 kernels to boot at all with the AMD IOMMU
>> enabled, I'd have a go at throwing that together now...
>
> It can share the dmar domain code. Let me frob something.

Not much to share there and I can't access my AMD machine at the
moment. Something like the untested below should work.

Thanks,

        tglx
---
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -523,7 +523,7 @@ struct msi_msg;
 struct irq_cfg;
 
 extern void __irq_msi_compose_msg(struct irq_cfg *cfg, struct msi_msg *msg,
-                                 bool dmar);
+                                 bool iommu);
 
 extern void ioapic_zap_locks(void);
 
--- a/arch/x86/include/asm/irqdomain.h
+++ b/arch/x86/include/asm/irqdomain.h
@@ -63,4 +63,6 @@ static inline void x86_create_pci_msi_do
 #define x86_pci_msi_default_domain     NULL
 #endif
 
+struct irq_domain *x86_create_iommu_msi_domain(void);
+
 #endif
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -2498,7 +2498,7 @@ int hard_smp_processor_id(void)
 }
 
 void __irq_msi_compose_msg(struct irq_cfg *cfg, struct msi_msg *msg,
-                          bool dmar)
+                          bool iommu)
 {
        memset(msg, 0, sizeof(*msg));
 
@@ -2519,7 +2519,7 @@ void __irq_msi_compose_msg(struct irq_cf
         * some hypervisors allow the extended destination ID field in bits
         * 5-11 to be used, giving support for 15 bits of APIC IDs in total.
         */
-       if (dmar)
+       if (iommu)
                msg->arch_addr_hi.destid_8_31 = cfg->dest_apicid >> 8;
        else if (virt_ext_dest_id && cfg->dest_apicid < 0x8000)
                msg->arch_addr_lo.virt_destid_8_14 = cfg->dest_apicid >> 8;
--- a/arch/x86/kernel/apic/msi.c
+++ b/arch/x86/kernel/apic/msi.c
@@ -184,7 +184,8 @@ static struct msi_domain_info pci_msi_do
        .handler_name   = "edge",
 };
 
-struct irq_domain * __init native_create_pci_msi_domain(void)
+static struct irq_domain *__init
+__create_pci_msi_domain(struct msi_domain_info *info, const char *name)
 {
        struct fwnode_handle *fn;
        struct irq_domain *d;
@@ -192,21 +193,25 @@ struct irq_domain * __init native_create
        if (disable_apic)
                return NULL;
 
-       fn = irq_domain_alloc_named_fwnode("PCI-MSI");
+       fn = irq_domain_alloc_named_fwnode(name);
        if (!fn)
                return NULL;
 
-       d = pci_msi_create_irq_domain(fn, &pci_msi_domain_info,
-                                     x86_vector_domain);
+       d = pci_msi_create_irq_domain(fn, info, x86_vector_domain);
        if (!d) {
                irq_domain_free_fwnode(fn);
-               pr_warn("Failed to initialize PCI-MSI irqdomain.\n");
+               pr_warn("Failed to initialize %s irqdomain.\n", name);
        } else {
                d->flags |= IRQ_DOMAIN_MSI_NOMASK_QUIRK;
        }
        return d;
 }
 
+struct irq_domain * __init native_create_pci_msi_domain(void)
+{
+       return __create_pci_msi_domain(&pci_msi_domain_info, "PCI-MSI");
+}
+
 void __init x86_create_pci_msi_domain(void)
 {
        x86_pci_msi_default_domain = x86_init.irqs.create_pci_msi_domain();
@@ -247,6 +252,43 @@ struct irq_domain *arch_create_remap_msi
 }
 #endif
 
+static void __maybe_unused iommu_msi_compose_msg(struct irq_data *data,
+                                                struct msi_msg *msg)
+{
+       __irq_msi_compose_msg(irqd_cfg(data), msg, true);
+}
+
+#ifdef CONFIG_AMD_IOMMU
+/*
+ * Similar to the Intel IOMMU abuse below. The resulting irq domain is
+ * associated to the IOMMU pci device, so that pci_enable_msi() works.
+ */
+static struct irq_chip iommu_msi_controller = {
+       .name                   = "IOMMU-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_set_affinity       = msi_set_affinity,
+       .irq_compose_msi_msg    = iommu_msi_compose_msg,
+       .flags                  = IRQCHIP_SKIP_SET_WAKE,
+};
+
+static struct msi_domain_info iommu_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           = &iommu_msi_controller,
+       .handler        = handle_edge_irq,
+       .handler_name   = "edge",
+};
+
+struct irq_domain __init *x86_create_iommu_msi_domain(void)
+{
+       return __create_pci_msi_domain(&iommu_msi_domain_info, "IOMMU-MSI");
+}
+#endif
+
 #ifdef CONFIG_DMAR_TABLE
 /*
  * The Intel IOMMU (ab)uses the high bits of the MSI address to contain the
@@ -254,11 +296,6 @@ struct irq_domain *arch_create_remap_msi
  * case for MSIs as it would be targeting real memory above 4GiB not the
  * APIC.
  */
-static void dmar_msi_compose_msg(struct irq_data *data, struct msi_msg *msg)
-{
-       __irq_msi_compose_msg(irqd_cfg(data), msg, true);
-}
-
 static void dmar_msi_write_msg(struct irq_data *data, struct msi_msg *msg)
 {
        dmar_msi_write(data->irq, msg);
@@ -271,7 +308,7 @@ static struct irq_chip dmar_msi_controll
        .irq_ack                = irq_chip_ack_parent,
        .irq_set_affinity       = msi_domain_set_affinity,
        .irq_retrigger          = irq_chip_retrigger_hierarchy,
-       .irq_compose_msi_msg    = dmar_msi_compose_msg,
+       .irq_compose_msi_msg    = iommu_msi_compose_msg,
        .irq_write_msi_msg      = dmar_msi_write_msg,
        .flags                  = IRQCHIP_SKIP_SET_WAKE,
 };
--- a/drivers/iommu/amd/init.c
+++ b/drivers/iommu/amd/init.c
@@ -1759,6 +1759,7 @@ static const struct attribute_group *amd
 
 static int __init iommu_init_pci(struct amd_iommu *iommu)
 {
+       static struct irq_domain *msidom;
        int cap_ptr = iommu->cap_ptr;
        int ret;
 
@@ -1767,6 +1768,13 @@ static int __init iommu_init_pci(struct
        if (!iommu->dev)
                return -ENODEV;
 
+       if (!msidom) {
+               msidom = x86_create_iommu_msi_domain();
+               if (!msidom)
+                       return -ENODEV;
+       }
+       dev_set_msi_domain(&iommu->dev->dev, msidom);
+
        /* Prevent binding other PCI device drivers to IOMMU devices */
        iommu->dev->match_driver = false;
 

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