[Qemu-devel] [PATCH 4/4] x86-iommu: turn on IR by default if proper

[Peter Xu <peterx@redhat.com>]

When the user didn't specify "intremap" for the IOMMU device, we turn
it on by default if it is supported.  This will turn IR on for the
default Q35 platform as long as the IOMMU device is specified on new
kernels.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 hw/i386/x86-iommu.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/hw/i386/x86-iommu.c b/hw/i386/x86-iommu.c
index 61ee0f1eaa..d1534c1ae0 100644
--- a/hw/i386/x86-iommu.c
+++ b/hw/i386/x86-iommu.c
@@ -112,6 +112,7 @@ static void x86_iommu_realize(DeviceState *dev, Error **errp)
     PCMachineState *pcms =
         PC_MACHINE(object_dynamic_cast(OBJECT(ms), TYPE_PC_MACHINE));
     QLIST_INIT(&x86_iommu->iec_notifiers);
+    bool irq_all_kernel = kvm_irqchip_in_kernel() && !kvm_irqchip_is_split();
 
     if (!pcms || !pcms->bus) {
         error_setg(errp, "Machine-type '%s' not supported by IOMMU",
@@ -121,12 +122,12 @@ static void x86_iommu_realize(DeviceState *dev, Error **errp)
 
     /* If the user didn't specify IR, choose a default value for it */
     if (x86_iommu->intr_supported == ON_OFF_AUTO_AUTO) {
-        x86_iommu->intr_supported = ON_OFF_AUTO_OFF;
+        x86_iommu->intr_supported = irq_all_kernel ?
+            ON_OFF_AUTO_OFF : ON_OFF_AUTO_ON;
     }
 
     /* Both Intel and AMD IOMMU IR only support "kernel-irqchip={off|split}" */
-    if (x86_iommu_ir_supported(x86_iommu) && kvm_irqchip_in_kernel() &&
-        !kvm_irqchip_is_split()) {
+    if (x86_iommu_ir_supported(x86_iommu) && irq_all_kernel) {
         error_setg(errp, "Interrupt Remapping cannot work with "
                          "kernel-irqchip=on, please use 'split|off'.");
         return;
-- 
2.17.1