qemu: format eim on intel-iommu command line

This option turns on extended interrupt mode,
which allows more than 255 vCPUs.

https://bugzilla.redhat.com/show_bug.cgi?id=1451282

Reviewed-by: Andrea Bolognani <abologna@redhat.com>

src/qemu/qemu_capabilities.c

@@ -371,6 +371,7 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
               "kernel-irqchip.split",
               "intel-iommu.intremap",
               "intel-iommu.caching-mode",
+              "intel-iommu.eim",
     );
 
 
@@ -1728,6 +1729,7 @@ static struct virQEMUCapsStringFlags virQEMUCapsObjectPropsUSBNECXHCI[] = {
 static struct virQEMUCapsStringFlags virQEMUCapsObjectPropsIntelIOMMU[] = {
     { "intremap", QEMU_CAPS_INTEL_IOMMU_INTREMAP },
     { "caching-mode", QEMU_CAPS_INTEL_IOMMU_CACHING_MODE },
+    { "eim", QEMU_CAPS_INTEL_IOMMU_EIM },
 };
 
 /* see documentation for virQEMUCapsQMPSchemaGetByPath for the query format */

src/qemu/qemu_capabilities.h

@@ -409,6 +409,7 @@ typedef enum {
     QEMU_CAPS_MACHINE_KERNEL_IRQCHIP_SPLIT, /* -machine kernel_irqchip=split */
     QEMU_CAPS_INTEL_IOMMU_INTREMAP, /* intel-iommu.intremap */
     QEMU_CAPS_INTEL_IOMMU_CACHING_MODE, /* intel-iommu.caching-mode */
+    QEMU_CAPS_INTEL_IOMMU_EIM, /* intel-iommu.eim */
 
     QEMU_CAPS_LAST /* this must always be the last item */
 } virQEMUCapsFlags;

src/qemu/qemu_command.c

@@ -6690,6 +6690,13 @@ qemuBuildIOMMUCommandLine(virCommandPtr cmd,
                              "with this QEMU binary"));
             return -1;
         }
+        if (iommu->eim != VIR_TRISTATE_SWITCH_ABSENT &&
+            !virQEMUCapsGet(qemuCaps, QEMU_CAPS_INTEL_IOMMU_EIM))  {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("iommu: eim is not supported "
+                             "with this QEMU binary"));
+            return -1;
+        }
         break;
     case VIR_DOMAIN_IOMMU_MODEL_LAST:
         break;
@@ -6723,6 +6730,10 @@ qemuBuildIOMMUCommandLine(virCommandPtr cmd,
             virBufferAsprintf(&opts, ",caching-mode=%s",
                               virTristateSwitchTypeToString(iommu->caching_mode));
         }
+        if (iommu->eim != VIR_TRISTATE_SWITCH_ABSENT) {
+            virBufferAsprintf(&opts, ",eim=%s",
+                              virTristateSwitchTypeToString(iommu->eim));
+        }
     case VIR_DOMAIN_IOMMU_MODEL_LAST:
         break;
     }

src/qemu/qemu_domain.c

@@ -2992,6 +2992,9 @@ qemuDomainDefValidateVideo(const virDomainDef *def)
 }
 
 
+#define QEMU_MAX_VCPUS_WITHOUT_EIM 255
+
+
 static int
 qemuDomainDefValidate(const virDomainDef *def,
                       virCapsPtr caps,
@@ -3071,6 +3074,24 @@ qemuDomainDefValidate(const virDomainDef *def,
         }
     }
 
+    if (ARCH_IS_X86(def->os.arch) &&
+        virDomainDefGetVcpusMax(def) > QEMU_MAX_VCPUS_WITHOUT_EIM) {
+        if (!qemuDomainIsQ35(def)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("more than %d vCPUs are only supported on "
+                             "q35-based machine types"),
+                           QEMU_MAX_VCPUS_WITHOUT_EIM);
+            goto cleanup;
+        }
+        if (!def->iommu || def->iommu->eim != VIR_TRISTATE_SWITCH_ON) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                           _("more than %d vCPUs require extended interrupt "
+                             "mode enabled on the iommu device"),
+                           QEMU_MAX_VCPUS_WITHOUT_EIM);
+            goto cleanup;
+        }
+    }
+
     if (qemuDomainDefValidateVideo(def) < 0)
         goto cleanup;
 

tests/qemucapabilitiesdata/caps_2.8.0.x86_64.xml

@@ -206,6 +206,7 @@
   <flag name='kernel-irqchip'/>
   <flag name='kernel-irqchip.split'/>
   <flag name='intel-iommu.intremap'/>
+  <flag name='intel-iommu.eim'/>
   <version>2008000</version>
   <kvmVersion>0</kvmVersion>
   <package> (v2.8.0)</package>

tests/qemucapabilitiesdata/caps_2.9.0.x86_64.xml

@@ -214,6 +214,7 @@
   <flag name='kernel-irqchip.split'/>
   <flag name='intel-iommu.intremap'/>
   <flag name='intel-iommu.caching-mode'/>
+  <flag name='intel-iommu.eim'/>
   <version>2009000</version>
   <kvmVersion>0</kvmVersion>
   <package> (v2.9.0)</package>

tests/qemuxml2argvdata/qemuxml2argv-intel-iommu-eim.args

@@ -0,0 +1,19 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-system-x86_64 \
+-name QEMUGuest1 \
+-S \
+-machine q35,accel=kvm,kernel_irqchip=split \
+-m 214 \
+-smp 288,sockets=288,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-nographic \
+-nodefaults \
+-monitor unix:/tmp/lib/domain--1-QEMUGuest1/monitor.sock,server,nowait \
+-no-acpi \
+-boot c \
+-device intel-iommu,intremap=on,eim=on

tests/qemuxml2argvtest.c

@@ -2529,6 +2529,13 @@ mymain(void)
             QEMU_CAPS_DEVICE_INTEL_IOMMU,
             QEMU_CAPS_INTEL_IOMMU_INTREMAP,
             QEMU_CAPS_INTEL_IOMMU_CACHING_MODE);
+    DO_TEST("intel-iommu-eim",
+            QEMU_CAPS_MACHINE_OPT,
+            QEMU_CAPS_MACHINE_KERNEL_IRQCHIP,
+            QEMU_CAPS_MACHINE_KERNEL_IRQCHIP_SPLIT,
+            QEMU_CAPS_INTEL_IOMMU_INTREMAP,
+            QEMU_CAPS_INTEL_IOMMU_EIM,
+            QEMU_CAPS_DEVICE_INTEL_IOMMU);
 
     DO_TEST("cpu-hotplug-startup", QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS);