qemu: format caching-mode on iommu command line

Format the caching-mode option for the intel-iommu device,
based on its <driver caching> attribute value.

https://bugzilla.redhat.com/show_bug.cgi?id=1427005

src/qemu/qemu_capabilities.c

@@ -370,6 +370,7 @@ VIR_ENUM_IMPL(virQEMUCaps, QEMU_CAPS_LAST,
               "kernel-irqchip", /* 255 */
               "kernel-irqchip.split",
               "intel-iommu.intremap",
+              "intel-iommu.caching-mode",
     );
 
 
@@ -1726,6 +1727,7 @@ static struct virQEMUCapsStringFlags virQEMUCapsObjectPropsUSBNECXHCI[] = {
 
 static struct virQEMUCapsStringFlags virQEMUCapsObjectPropsIntelIOMMU[] = {
     { "intremap", QEMU_CAPS_INTEL_IOMMU_INTREMAP },
+    { "caching-mode", QEMU_CAPS_INTEL_IOMMU_CACHING_MODE },
 };
 
 /* see documentation for virQEMUCapsQMPSchemaGetByPath for the query format */

src/qemu/qemu_capabilities.h

@@ -408,6 +408,7 @@ typedef enum {
     QEMU_CAPS_MACHINE_KERNEL_IRQCHIP, /* -machine kernel_irqchip */
     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_LAST /* this must always be the last item */
 } virQEMUCapsFlags;

src/qemu/qemu_command.c

@@ -6694,6 +6694,13 @@ qemuBuildIOMMUCommandLine(virCommandPtr cmd,
                              "with this QEMU binary"));
             return -1;
         }
+        if (iommu->caching_mode != VIR_TRISTATE_SWITCH_ABSENT &&
+            !virQEMUCapsGet(qemuCaps, QEMU_CAPS_INTEL_IOMMU_CACHING_MODE))  {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("iommu: caching mode 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, ",intremap=%s",
                               virTristateSwitchTypeToString(iommu->intremap));
         }
+        if (iommu->caching_mode != VIR_TRISTATE_SWITCH_ABSENT) {
+            virBufferAsprintf(&opts, ",caching-mode=%s",
+                              virTristateSwitchTypeToString(iommu->caching_mode));
+        }
     case VIR_DOMAIN_IOMMU_MODEL_LAST:
         break;
     }

tests/qemucapabilitiesdata/caps_2.9.0.x86_64.xml

@@ -213,6 +213,7 @@
   <flag name='kernel-irqchip'/>
   <flag name='kernel-irqchip.split'/>
   <flag name='intel-iommu.intremap'/>
+  <flag name='intel-iommu.caching-mode'/>
   <version>2009000</version>
   <kvmVersion>0</kvmVersion>
   <package> (v2.9.0)</package>

tests/qemuxml2argvdata/qemuxml2argv-intel-iommu-caching-mode.args

@@ -0,0 +1,25 @@
+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=tcg \
+-m 214 \
+-smp 1,sockets=1,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,caching-mode=on \
+-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
+-device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x0 \
+-device ioh3420,port=0x10,chassis=3,id=pci.3,bus=pcie.0,addr=0x2 \
+-device ich9-usb-ehci1,id=usb,bus=pci.2,addr=0x2.0x7 \
+-device rtl8139,vlan=0,id=net0,mac=52:54:00:ab:0c:5c,bus=pci.2,addr=0x1 \
+-net user,vlan=0,name=hostnet0

tests/qemuxml2argvtest.c

@@ -2515,6 +2515,17 @@ mymain(void)
             QEMU_CAPS_MACHINE_KERNEL_IRQCHIP_SPLIT,
             QEMU_CAPS_INTEL_IOMMU_INTREMAP,
             QEMU_CAPS_DEVICE_INTEL_IOMMU);
+    DO_TEST("intel-iommu-caching-mode",
+            QEMU_CAPS_MACHINE_OPT,
+            QEMU_CAPS_DEVICE_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_DMI_TO_PCI_BRIDGE,
+            QEMU_CAPS_DEVICE_IOH3420,
+            QEMU_CAPS_ICH9_AHCI,
+            QEMU_CAPS_PCI_MULTIFUNCTION,
+            QEMU_CAPS_ICH9_USB_EHCI1,
+            QEMU_CAPS_DEVICE_INTEL_IOMMU,
+            QEMU_CAPS_INTEL_IOMMU_INTREMAP,
+            QEMU_CAPS_INTEL_IOMMU_CACHING_MODE);
 
     DO_TEST("cpu-hotplug-startup", QEMU_CAPS_QUERY_HOTPLUGGABLE_CPUS);