From: Nathan Chen <nathanc@nvidia.com>

Introduce support for an "identifier" IOMMU attribute that
allows the CMDQV DSDT device to be correctly associated with
its SMMU.

Signed-off-by: Nathan Chen <nathanc@nvidia.com>
---
 docs/formatdomain.rst             |  7 +++++++
 src/conf/domain_conf.c            | 17 +++++++++++++++++
 src/conf/domain_conf.h            |  1 +
 src/conf/domain_validate.c        |  5 ++++-
 src/conf/schemas/domaincommon.rng |  5 +++++
 src/qemu/qemu_command.c           |  1 +
 6 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index 74431838ff..c5eb4ac886 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -9347,6 +9347,13 @@ Examples:
       passthrough of physical SMMU-CMDQ linked command queue from host space to VM.
       :since:`Since 12.1.0` (QEMU/KVM and ``smmuv3`` model only)
 
+   ``identifier``
+      The ``identifier`` attribute can be used to provide a stable per-device
+      identifier independent of enumeration order. This attribute is required for
+      supporting NVIDIA Tegra241 CMDQV, and is used to correctly associate the
+      CMDQV DSDT device with its SMMU.
+      :since:`Since 12.1.0` (QEMU/KVM and ``smmuv3`` model only)
+
 In case of ``virtio`` IOMMU device, the ``driver`` element can optionally
 contain ``granule`` subelement that allows to choose which granule will be
 used by default. It is useful when running guests with different page size
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index 6385420c10..0c11a3e2bc 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -2852,6 +2852,8 @@ virDomainIOMMUDefNew(void)
 
     iommu->pci_bus = -1;
 
+    iommu->identifier = -1;
+
     return g_steal_pointer(&iommu);
 }
 
@@ -14684,6 +14686,10 @@ virDomainIOMMUDefParseXML(virDomainXMLOption *xmlopt,
                                      &iommu->cmdqv) < 0)
             return NULL;
 
+        if (virXMLPropInt(driver, "identifier", 10, VIR_XML_PROP_NONE,
+                          &iommu->identifier, -1) < 0)
+            return NULL;
+
         if ((granule = virXPathNode("./driver/granule", ctxt))) {
             g_autofree char *mode = virXMLPropString(granule, "mode");
             unsigned long long size;
@@ -16786,6 +16792,7 @@ virDomainIOMMUDefEquals(const virDomainIOMMUDef *a,
         a->aw_bits != b->aw_bits ||
         a->dma_translation != b->dma_translation ||
         a->cmdqv != b->cmdqv ||
+        a->identifier != b->identifier ||
         a->granule != b->granule)
         return false;
 
@@ -22548,6 +22555,12 @@ virDomainIOMMUDefCheckABIStability(virDomainIOMMUDef *src,
                        dst->cmdqv, src->cmdqv);
         return false;
     }
+    if (src->identifier != dst->identifier) {
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("Target domain IOMMU device identifier '%1$d' does not match source '%2$d'"),
+                       dst->identifier,
+                       src->identifier);
+    }
     if (src->dma_translation != dst->dma_translation) {
         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                        _("Target domain IOMMU device dma translation '%1$s' does not match source '%2$s'"),
@@ -28956,6 +28969,10 @@ virDomainIOMMUDefFormat(virBuffer *buf,
         virBufferAsprintf(&driverAttrBuf, " cmdqv='%s'",
                           virTristateSwitchTypeToString(iommu->cmdqv));
     }
+    if (iommu->identifier >= 0) {
+        virBufferAsprintf(&driverAttrBuf, " identifier='%d'",
+                          iommu->identifier);
+    }
     if (iommu->granule != 0) {
         if (iommu->granule == -1) {
             virBufferAddLit(&driverChildBuf, "<granule mode='host'/>\n");
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index 41dba29a4f..2cf414d307 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -3076,6 +3076,7 @@ struct _virDomainIOMMUDef {
     virTristateSwitch pt;
     int granule; /* -1 means 'host', 0 unset, page size in KiB otherwise */
     virTristateSwitch cmdqv;
+    int identifier;
 };
 
 typedef enum {
diff --git a/src/conf/domain_validate.c b/src/conf/domain_validate.c
index cac5dabf06..9cd8efae52 100644
--- a/src/conf/domain_validate.c
+++ b/src/conf/domain_validate.c
@@ -3209,7 +3209,8 @@ virDomainIOMMUDefValidate(const virDomainIOMMUDef *iommu)
             iommu->iotlb != VIR_TRISTATE_SWITCH_ABSENT ||
             iommu->dma_translation != VIR_TRISTATE_SWITCH_ABSENT ||
             iommu->pci_bus >= 0 ||
-            iommu->cmdqv != VIR_TRISTATE_SWITCH_ABSENT) {
+            iommu->cmdqv != VIR_TRISTATE_SWITCH_ABSENT ||
+            iommu->identifier >= 0) {
             virReportError(VIR_ERR_XML_ERROR,
                            _("iommu model '%1$s' doesn't support some additional attributes"),
                            virDomainIOMMUModelTypeToString(iommu->model));
@@ -3233,6 +3234,7 @@ virDomainIOMMUDefValidate(const virDomainIOMMUDef *iommu)
             iommu->dma_translation != VIR_TRISTATE_SWITCH_ABSENT ||
             iommu->pci_bus >= 0 ||
             iommu->cmdqv != VIR_TRISTATE_SWITCH_ABSENT ||
+            iommu->identifier >= 0 ||
             iommu->granule != 0) {
             virReportError(VIR_ERR_XML_ERROR,
                            _("iommu model '%1$s' doesn't support some additional attributes"),
@@ -3246,6 +3248,7 @@ virDomainIOMMUDefValidate(const virDomainIOMMUDef *iommu)
             iommu->xtsup != VIR_TRISTATE_SWITCH_ABSENT ||
             iommu->pci_bus >= 0 ||
             iommu->cmdqv != VIR_TRISTATE_SWITCH_ABSENT ||
+            iommu->identifier >= 0 ||
             iommu->granule != 0) {
             virReportError(VIR_ERR_XML_ERROR,
                            _("iommu model '%1$s' doesn't support some additional attributes"),
diff --git a/src/conf/schemas/domaincommon.rng b/src/conf/schemas/domaincommon.rng
index 2677207ae4..ab142502e7 100644
--- a/src/conf/schemas/domaincommon.rng
+++ b/src/conf/schemas/domaincommon.rng
@@ -6357,6 +6357,11 @@
                 <ref name="virOnOff"/>
               </attribute>
             </optional>
+            <optional>
+              <attribute name="identifier">
+                <data type="unsignedInt"/>
+              </attribute>
+            </optional>
             <optional>
               <element name="granule">
                 <choice>
diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c
index 3735387ebd..37bb876b66 100644
--- a/src/qemu/qemu_command.c
+++ b/src/qemu/qemu_command.c
@@ -6331,6 +6331,7 @@ qemuBuildPCINestedSmmuv3DevProps(const virDomainDef *def,
                               "s:primary-bus", bus,
                               "s:id", iommu->info.alias,
                               "B:tegra241-cmdqv", (iommu->cmdqv == VIR_TRISTATE_SWITCH_ON),
+                              "k:identifier", iommu->identifier,
                               NULL) < 0)
         return NULL;
 
-- 
2.43.0