File 5d41793f-AMD-IOMMU-allow-enabling-without-IRQ.patch of Package xen.13549

# Commit 5f569f1ac50eff9dc95ac2e4a617de657d254b52
# Date 2019-07-31 13:19:27 +0200
# Author Jan Beulich <jbeulich@suse.com>
# Committer Jan Beulich <jbeulich@suse.com>
AMD/IOMMU: allow enabling with IRQ not yet set up

Early enabling (to enter x2APIC mode) requires deferring of the IRQ
setup. Code to actually do that setup in the x2APIC case will get added
subsequently.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>
Acked-by: Brian Woods <brian.woods@amd.com>

--- a/xen/drivers/passthrough/amd/iommu_init.c
+++ b/xen/drivers/passthrough/amd/iommu_init.c
@@ -814,7 +814,6 @@ static void amd_iommu_erratum_746_workar
 static void enable_iommu(struct amd_iommu *iommu)
 {
     unsigned long flags;
-    struct irq_desc *desc;
 
     spin_lock_irqsave(&iommu->lock, flags);
 
@@ -834,19 +833,27 @@ static void enable_iommu(struct amd_iomm
     if ( iommu->features.flds.ppr_sup )
         register_iommu_ppr_log_in_mmio_space(iommu);
 
-    desc = irq_to_desc(iommu->msi.irq);
-    spin_lock(&desc->lock);
-    set_msi_affinity(desc, NULL);
-    spin_unlock(&desc->lock);
+    if ( iommu->msi.irq > 0 )
+    {
+        struct irq_desc *desc = irq_to_desc(iommu->msi.irq);
+
+        spin_lock(&desc->lock);
+        set_msi_affinity(desc, NULL);
+        spin_unlock(&desc->lock);
+    }
 
     amd_iommu_msi_enable(iommu, IOMMU_CONTROL_ENABLED);
 
     set_iommu_ht_flags(iommu);
     set_iommu_command_buffer_control(iommu, IOMMU_CONTROL_ENABLED);
-    set_iommu_event_log_control(iommu, IOMMU_CONTROL_ENABLED);
 
-    if ( iommu->features.flds.ppr_sup )
-        set_iommu_ppr_log_control(iommu, IOMMU_CONTROL_ENABLED);
+    if ( iommu->msi.irq > 0 )
+    {
+        set_iommu_event_log_control(iommu, IOMMU_CONTROL_ENABLED);
+
+        if ( iommu->features.flds.ppr_sup )
+            set_iommu_ppr_log_control(iommu, IOMMU_CONTROL_ENABLED);
+    }
 
     if ( iommu->features.flds.gt_sup )
         set_iommu_guest_translation_control(iommu, IOMMU_CONTROL_ENABLED);