[PATCH V2 1/4] conf: Add support for specifying CPU max physical address size

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From: Dario Faggioli <dfaggioli@xxxxxxxx>

This patch introduces the

    <maxphysaddr mode='passthrough'/>
    <maxphysaddr mode='emulate' bits='42'/>

sub element of /domain/cpu, which allows specifying the guest virtual CPU
address size. This can be useful if the guest needs to have a large amount
of memory.

If mode='passthrough', the virtual CPU will have the same number of address
bits as the host. If mode='emulate', the mandatory bits attribute specifies
the number of address bits.

Signed-off-by: Dario Faggioli <dfaggioli@xxxxxxxx>
Signed-off-by: Jim Fehlig <jfehlig@xxxxxxxx>
---
 docs/formatdomain.rst                         | 23 ++++++++
 src/conf/cpu_conf.c                           | 54 +++++++++++++++++++
 src/conf/cpu_conf.h                           | 17 ++++++
 src/conf/schemas/cputypes.rng                 | 19 +++++++
 src/libvirt_private.syms                      |  2 +
 .../cpu-phys-bits-emulate.xml                 | 20 +++++++
 .../cpu-phys-bits-passthrough.xml             | 20 +++++++
 tests/genericxml2xmltest.c                    |  3 ++
 8 files changed, 158 insertions(+)

diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst
index 1ed969ac3e..adfdd7b7a5 100644
--- a/docs/formatdomain.rst
+++ b/docs/formatdomain.rst
@@ -1336,6 +1336,7 @@ following collection of elements. :since:`Since 0.7.5`
      <vendor>Intel</vendor>
      <topology sockets='1' dies='1' cores='2' threads='1'/>
      <cache level='3' mode='emulate'/>
+     <maxphysaddr mode='emulate' bits='42'>
      <feature policy='disable' name='lahf_lm'/>
    </cpu>
    ...
@@ -1352,6 +1353,7 @@ following collection of elements. :since:`Since 0.7.5`
 
    <cpu mode='host-passthrough' migratable='off'>
      <cache mode='passthrough'/>
+     <maxphysaddr mode='passthrough'>
      <feature policy='disable' name='lahf_lm'/>
    ...
 
@@ -1600,6 +1602,27 @@ In case no restrictions need to be put on CPU model and its features, a simpler
          The virtual CPU will report no CPU cache of the specified level (or no
          cache at all if the ``level`` attribute is missing).
 
+``maxphysaddr``
+   :since:`Since 8.7.0` the ``maxphysaddr`` element describes the virtual CPU
+   address size in bits. The hypervisor default is used if the element is missing.
+
+   ``mode``
+      This mandatory attribute specifies how the address size is presented. The
+      follow modes are supported:
+
+      ``passthrough``
+         The number of physical address bits reported by the host CPU will be
+         passed through to the virtual CPUs
+      ``emulate``
+         The hypervisor will define a specific value for the number of bits
+         of physical addresses via the ``bits`` attribute, which is mandatory.
+	 The number of bits cannot exceed the number of physical address bits
+	 supported by the hypervisor.
+
+   ``bits``
+      The ``bits`` attribute is mandatory if the ``mode`` attribute is set to
+      ``emulate`` and specifies the virtual CPU address size in bits.
+
 Guest NUMA topology can be specified using the ``numa`` element. :since:`Since
 0.9.8`
 
diff --git a/src/conf/cpu_conf.c b/src/conf/cpu_conf.c
index 8d80bbd842..e31c4ab467 100644
--- a/src/conf/cpu_conf.c
+++ b/src/conf/cpu_conf.c
@@ -82,6 +82,12 @@ VIR_ENUM_IMPL(virCPUCacheMode,
               "disable",
 );
 
+VIR_ENUM_IMPL(virCPUMaxPhysAddrMode,
+              VIR_CPU_MAX_PHYS_ADDR_MODE_LAST,
+              "emulate",
+              "passthrough",
+);
+
 
 virCPUDef *virCPUDefNew(void)
 {
@@ -127,6 +133,7 @@ virCPUDefFree(virCPUDef *def)
     if (g_atomic_int_dec_and_test(&def->refs)) {
         virCPUDefFreeModel(def);
         g_free(def->cache);
+        g_free(def->addr);
         g_free(def->tsc);
         g_free(def);
     }
@@ -252,6 +259,11 @@ virCPUDefCopyWithoutModel(const virCPUDef *cpu)
         *copy->cache = *cpu->cache;
     }
 
+    if (cpu->addr) {
+        copy->addr = g_new0(virCPUMaxPhysAddrDef, 1);
+        *copy->addr = *cpu->addr;
+    }
+
     if (cpu->tsc) {
         copy->tsc = g_new0(virHostCPUTscInfo, 1);
         *copy->tsc = *cpu->tsc;
@@ -644,6 +656,39 @@ virCPUDefParseXML(xmlXPathContextPtr ctxt,
         def->cache->mode = mode;
     }
 
+    if (virXPathInt("count(./maxphysaddr)", ctxt, &n) < 0) {
+        return -1;
+    } else if (n > 1) {
+        virReportError(VIR_ERR_XML_ERROR, "%s",
+                       _("at most one CPU maximum physical address bits "
+                         "element may be specified"));
+        return -1;
+    } else if (n == 1) {
+        g_autofree char *strmode = NULL;
+        int mode;
+        int bits = -1;
+
+        if (!(strmode = virXPathString("string(./maxphysaddr[1]/@mode)", ctxt)) ||
+            (mode = virCPUMaxPhysAddrModeTypeFromString(strmode)) < 0) {
+            virReportError(VIR_ERR_XML_ERROR, "%s",
+                           _("missing or invalid CPU maximum physical "
+                             "address bits mode"));
+            return -1;
+        }
+
+        if (virXPathBoolean("boolean(./maxphysaddr[1]/@bits)", ctxt) == 1 &&
+            (virXPathInt("string(./maxphysaddr[1]/@bits)", ctxt, &bits) < 0 ||
+             bits < 0)) {
+            virReportError(VIR_ERR_XML_ERROR, "%s",
+                           _("CPU maximum physical address bits < 0"));
+            return -1;
+        }
+
+        def->addr = g_new0(virCPUMaxPhysAddrDef, 1);
+        def->addr->bits = bits;
+        def->addr->mode = mode;
+    }
+
     *cpu = g_steal_pointer(&def);
     return 0;
 }
@@ -811,6 +856,15 @@ virCPUDefFormatBuf(virBuffer *buf,
         virBufferAddLit(buf, "/>\n");
     }
 
+    if (def->addr) {
+        virBufferAddLit(buf, "<maxphysaddr ");
+        virBufferAsprintf(buf, "mode='%s'",
+                          virCPUMaxPhysAddrModeTypeToString(def->addr->mode));
+        if (def->addr->bits != -1)
+            virBufferAsprintf(buf, " bits='%d'", def->addr->bits);
+        virBufferAddLit(buf, "/>\n");
+    }
+
     for (i = 0; i < def->nfeatures; i++) {
         virCPUFeatureDef *feature = def->features + i;
 
diff --git a/src/conf/cpu_conf.h b/src/conf/cpu_conf.h
index 5d2980edbd..113d349708 100644
--- a/src/conf/cpu_conf.h
+++ b/src/conf/cpu_conf.h
@@ -116,6 +116,22 @@ struct _virCPUCacheDef {
 };
 
 
+typedef enum {
+    VIR_CPU_MAX_PHYS_ADDR_MODE_EMULATE,
+    VIR_CPU_MAX_PHYS_ADDR_MODE_PASSTHROUGH,
+
+    VIR_CPU_MAX_PHYS_ADDR_MODE_LAST
+} virCPUMaxPhysAddrMode;
+
+VIR_ENUM_DECL(virCPUMaxPhysAddrMode);
+
+typedef struct _virCPUMaxPhysAddrDef virCPUMaxPhysAddrDef;
+struct _virCPUMaxPhysAddrDef {
+    int bits;           /* -1 for unspecified */
+    virCPUMaxPhysAddrMode mode;
+};
+
+
 typedef struct _virCPUDef virCPUDef;
 struct _virCPUDef {
     int refs;
@@ -140,6 +156,7 @@ struct _virCPUDef {
     size_t nfeatures_max;
     virCPUFeatureDef *features;
     virCPUCacheDef *cache;
+    virCPUMaxPhysAddrDef *addr;
     virHostCPUTscInfo *tsc;
     virTristateSwitch migratable; /* for host-passthrough mode */
 };
diff --git a/src/conf/schemas/cputypes.rng b/src/conf/schemas/cputypes.rng
index 122880fb2e..4ae386c3c0 100644
--- a/src/conf/schemas/cputypes.rng
+++ b/src/conf/schemas/cputypes.rng
@@ -305,6 +305,22 @@
     </element>
   </define>
 
+  <define name="cpuMaxPhysAddr">
+    <element name="maxphysaddr">
+      <attribute name="mode">
+        <choice>
+          <value>emulate</value>
+          <value>passthrough</value>
+        </choice>
+      </attribute>
+      <optional>
+        <attribute name="bits">
+          <ref name="unsignedInt"/>
+        </attribute>
+      </optional>
+    </element>
+  </define>
+
   <define name="hostcpu">
     <element name="cpu">
       <element name="arch">
@@ -432,6 +448,9 @@
         <optional>
           <ref name="cpuCache"/>
         </optional>
+        <optional>
+          <ref name="cpuMaxPhysAddr"/>
+        </optional>
       </interleave>
     </element>
   </define>
diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
index 6a5c5600df..774a594983 100644
--- a/src/libvirt_private.syms
+++ b/src/libvirt_private.syms
@@ -120,6 +120,8 @@ virCPUDefParseXMLString;
 virCPUDefRef;
 virCPUDefStealModel;
 virCPUDefUpdateFeature;
+virCPUMaxPhysAddrModeTypeFromString;
+virCPUMaxPhysAddrModeTypeToString;
 virCPUModeTypeToString;
 
 
diff --git a/tests/genericxml2xmlindata/cpu-phys-bits-emulate.xml b/tests/genericxml2xmlindata/cpu-phys-bits-emulate.xml
new file mode 100644
index 0000000000..e463e0b3e0
--- /dev/null
+++ b/tests/genericxml2xmlindata/cpu-phys-bits-emulate.xml
@@ -0,0 +1,20 @@
+<domain type='kvm'>
+  <name>foo</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <cpu mode='host-passthrough'>
+    <maxphysaddr mode='emulate' bits='42'/>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+  </devices>
+</domain>
diff --git a/tests/genericxml2xmlindata/cpu-phys-bits-passthrough.xml b/tests/genericxml2xmlindata/cpu-phys-bits-passthrough.xml
new file mode 100644
index 0000000000..cce676eaa6
--- /dev/null
+++ b/tests/genericxml2xmlindata/cpu-phys-bits-passthrough.xml
@@ -0,0 +1,20 @@
+<domain type='kvm'>
+  <name>foo</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219136</memory>
+  <currentMemory unit='KiB'>219136</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='i686' machine='pc'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <cpu mode='host-passthrough'>
+    <maxphysaddr mode='passthrough'/>
+  </cpu>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+  </devices>
+</domain>
diff --git a/tests/genericxml2xmltest.c b/tests/genericxml2xmltest.c
index b83367cb4b..bbe0d02226 100644
--- a/tests/genericxml2xmltest.c
+++ b/tests/genericxml2xmltest.c
@@ -246,6 +246,9 @@ mymain(void)
 
     DO_TEST_BACKUP_FULL("backup-pull-internal-invalid", true);
 
+    DO_TEST("cpu-phys-bits-emulate");
+    DO_TEST("cpu-phys-bits-passthrough");
+
 
     virObjectUnref(caps);
     virObjectUnref(xmlopt);
-- 
2.36.1





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