If a Q35 domain has huge number of vCPUS (over 255, currently), then
it needs IOMMU with Extended Interrupt Mode enabled (see check in
qemuValidateDomainVCpuTopology()).

Well, we already add some devices and to other tricks when
parsing new domain XML. Might as well turn the EIM on for IOMMU
device.

Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
---
 src/qemu/qemu_domain.c                        | 37 ++++++++++++++++++-
 src/qemu/qemu_validate.c                      |  1 -
 src/qemu/qemu_validate.h                      |  2 +
 ...-eim-autoadd.x86_64-latest.abi-update.args | 34 +++++++++++++++++
 ...u-eim-autoadd.x86_64-latest.abi-update.xml | 37 +++++++++++++++++++
 .../intel-iommu-eim-autoadd.xml               | 35 ++++++++++++++++++
 tests/qemuxmlconftest.c                       |  1 +
 7 files changed, 145 insertions(+), 2 deletions(-)
 create mode 100644 tests/qemuxmlconfdata/intel-iommu-eim-autoadd.x86_64-latest.abi-update.args
 create mode 100644 tests/qemuxmlconfdata/intel-iommu-eim-autoadd.x86_64-latest.abi-update.xml
 create mode 100644 tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index 7b702cfc6b..39f3e38351 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -6453,6 +6453,37 @@ qemuDomainPstoreDefPostParse(virDomainPstoreDef *pstore,
 }
 
 
+static int
+qemuDomainIOMMUDefPostParse(virDomainIOMMUDef *iommu,
+                            const virDomainDef *def,
+                            virQEMUCaps *qemuCaps,
+                            unsigned int parseFlags)
+{
+    /* In case domain has huge number of vCPUS and Extended Interrupt Mode
+     * (EIM) is not explicitly turned off, let's enable it. If we didn't then
+     * guest will have troubles with interrupts. */
+    if (parseFlags & VIR_DOMAIN_DEF_PARSE_ABI_UPDATE &&
+        ARCH_IS_X86(def->os.arch) &&
+        virDomainDefGetVcpusMax(def) > QEMU_MAX_VCPUS_WITHOUT_EIM &&
+        qemuDomainIsQ35(def) &&
+        iommu && iommu->model == VIR_DOMAIN_IOMMU_MODEL_INTEL) {
+
+        /* eim requires intremap. */
+        if (iommu->intremap == VIR_TRISTATE_SWITCH_ABSENT &&
+            virQEMUCapsGet(qemuCaps, QEMU_CAPS_INTEL_IOMMU_INTREMAP)) {
+            iommu->intremap = VIR_TRISTATE_SWITCH_ON;
+        }
+
+        if (iommu->eim == VIR_TRISTATE_SWITCH_ABSENT &&
+            virQEMUCapsGet(qemuCaps, QEMU_CAPS_INTEL_IOMMU_EIM)) {
+            iommu->eim = VIR_TRISTATE_SWITCH_ON;
+        }
+    }
+
+    return 0;
+}
+
+
 static int
 qemuDomainDeviceDefPostParse(virDomainDeviceDef *dev,
                              const virDomainDef *def,
@@ -6518,6 +6549,11 @@ qemuDomainDeviceDefPostParse(virDomainDeviceDef *dev,
         ret = qemuDomainPstoreDefPostParse(dev->data.pstore, def, driver);
         break;
 
+    case VIR_DOMAIN_DEVICE_IOMMU:
+        ret = qemuDomainIOMMUDefPostParse(dev->data.iommu, def,
+                                          qemuCaps, parseFlags);
+        break;
+
     case VIR_DOMAIN_DEVICE_LEASE:
     case VIR_DOMAIN_DEVICE_FS:
     case VIR_DOMAIN_DEVICE_INPUT:
@@ -6530,7 +6566,6 @@ qemuDomainDeviceDefPostParse(virDomainDeviceDef *dev,
     case VIR_DOMAIN_DEVICE_MEMBALLOON:
     case VIR_DOMAIN_DEVICE_NVRAM:
     case VIR_DOMAIN_DEVICE_RNG:
-    case VIR_DOMAIN_DEVICE_IOMMU:
     case VIR_DOMAIN_DEVICE_AUDIO:
     case VIR_DOMAIN_DEVICE_CRYPTO:
         ret = 0;
diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c
index fa23c5f973..aaa056379e 100644
--- a/src/qemu/qemu_validate.c
+++ b/src/qemu/qemu_validate.c
@@ -31,7 +31,6 @@
 #include "virutil.h"
 
 #define VIR_FROM_THIS VIR_FROM_QEMU
-#define QEMU_MAX_VCPUS_WITHOUT_EIM 255
 
 VIR_LOG_INIT("qemu.qemu_validate");
 
diff --git a/src/qemu/qemu_validate.h b/src/qemu/qemu_validate.h
index e06a43b8e3..9315be73f5 100644
--- a/src/qemu/qemu_validate.h
+++ b/src/qemu/qemu_validate.h
@@ -22,6 +22,8 @@
 
 #include "qemu_capabilities.h"
 
+#define QEMU_MAX_VCPUS_WITHOUT_EIM 255
+
 int
 qemuValidateDomainDef(const virDomainDef *def,
                       void *opaque,
diff --git a/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.x86_64-latest.abi-update.args b/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.x86_64-latest.abi-update.args
new file mode 100644
index 0000000000..07fa1191b7
--- /dev/null
+++ b/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.x86_64-latest.abi-update.args
@@ -0,0 +1,34 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1 \
+USER=test \
+LOGNAME=test \
+XDG_DATA_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.local/share \
+XDG_CACHE_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.cache \
+XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain--1-QEMUGuest1/.config \
+/usr/bin/qemu-system-x86_64 \
+-name guest=QEMUGuest1,debug-threads=on \
+-S \
+-object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/var/lib/libvirt/qemu/domain--1-QEMUGuest1/master-key.aes"}' \
+-machine q35,usb=off,kernel_irqchip=split,dump-guest-core=off,memory-backend=pc.ram,acpi=off \
+-accel kvm \
+-cpu qemu64 \
+-m size=219136k \
+-object '{"qom-type":"memory-backend-ram","id":"pc.ram","size":224395264}' \
+-overcommit mem-lock=off \
+-smp 288,sockets=288,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-display none \
+-no-user-config \
+-nodefaults \
+-chardev socket,id=charmonitor,fd=1729,server=on,wait=off \
+-mon chardev=charmonitor,id=monitor,mode=control \
+-rtc base=utc \
+-no-shutdown \
+-boot strict=on \
+-device '{"driver":"intel-iommu","id":"iommu0","intremap":"on","eim":"on"}' \
+-audiodev '{"id":"audio1","driver":"none"}' \
+-global ICH9-LPC.noreboot=off \
+-watchdog-action reset \
+-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
+-msg timestamp=on
diff --git a/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.x86_64-latest.abi-update.xml b/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.x86_64-latest.abi-update.xml
new file mode 100644
index 0000000000..1caa0ceb60
--- /dev/null
+++ b/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.x86_64-latest.abi-update.xml
@@ -0,0 +1,37 @@
+<domain type='kvm'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static'>288</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <features>
+    <ioapic driver='qemu'/>
+  </features>
+  <cpu mode='custom' match='exact' check='none'>
+    <model fallback='forbid'>qemu64</model>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='usb' index='0' model='none'/>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <audio id='1' type='none'/>
+    <watchdog model='itco' action='reset'/>
+    <memballoon model='none'/>
+    <iommu model='intel'>
+      <driver intremap='on' eim='on'/>
+    </iommu>
+  </devices>
+</domain>
diff --git a/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml b/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml
new file mode 100644
index 0000000000..7c294fe2f9
--- /dev/null
+++ b/tests/qemuxmlconfdata/intel-iommu-eim-autoadd.xml
@@ -0,0 +1,35 @@
+<domain type='kvm'>
+  <name>QEMUGuest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static'>288</vcpu>
+  <os>
+    <type arch='x86_64' machine='q35'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <features>
+    <ioapic driver='qemu'/>
+  </features>
+  <cpu mode='custom' match='exact' check='none'>
+    <model fallback='forbid'>qemu64</model>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/bin/qemu-system-x86_64</emulator>
+    <controller type='pci' index='0' model='pcie-root'/>
+    <controller type='usb' index='0' model='none'/>
+    <controller type='sata' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
+    </controller>
+    <input type='mouse' bus='ps2'/>
+    <input type='keyboard' bus='ps2'/>
+    <audio id='1' type='none'/>
+    <watchdog model='itco' action='reset'/>
+    <memballoon model='none'/>
+    <iommu model='intel'/>
+  </devices>
+</domain>
diff --git a/tests/qemuxmlconftest.c b/tests/qemuxmlconftest.c
index 9bcd937447..2b94d5dc63 100644
--- a/tests/qemuxmlconftest.c
+++ b/tests/qemuxmlconftest.c
@@ -2764,6 +2764,7 @@ mymain(void)
     DO_TEST_CAPS_LATEST("intel-iommu-aw-bits");
     DO_TEST_CAPS_LATEST("intel-iommu-dma-translation");
     DO_TEST_CAPS_LATEST_PARSE_ERROR("intel-iommu-wrong-machine");
+    DO_TEST_CAPS_LATEST_ABI_UPDATE("intel-iommu-eim-autoadd");
     DO_TEST_CAPS_ARCH_LATEST("iommu-smmuv3", "aarch64");
     DO_TEST_CAPS_LATEST("virtio-iommu-x86_64");
     DO_TEST_CAPS_VER_PARSE_ERROR("virtio-iommu-x86_64", "6.1.0");
-- 
2.45.2