[libvirt] add ivshmem property master

[Martin Kletzander]

[Please use git send-email or a normal client, this attachment is difficult to
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On Fri, Feb 01, 2019 at 08:16:20AM +0000, 吴 雨霖 wrote:
>[Problem Description]
>
>  I read qemu-doc.texi in qemu-mster source code, which have a explain of migrating ivshmem below
>
>“With device property @option{master=on}, the guest will copy the shared.memory on migration to the destination host.  With @option{master=off}, the guest will not be able to migrate with the device attached.”
>
>  However, libvirt library can not recognize the property “master=on”. When I directly used command "qemu-kvm -device ivshmem-plain,id=shmem0,memdev=shmmem-shmem0,master=on,bus=pci.0,addr=0xa” to launch a guest, qemu support ivshmem property master=on.
>
>  So, I suggest adding code to support property master=on in libvirt.
>

QEMU supports that, but libvirt doesn't.  I remember there was a reason
for it, but I can't seem to recall what the particular reason was.

What is the reason for you to need master=on?

>
>
>[Code Review]
>
>
>
>    The below is the part of source code in qemu-master. There's no definition here  about ivshmem master.
>
>domain_conf.h
>
>struct _virDomainShmemDef {
>
>    char *name;
>
>    unsigned long long size;
>
>    int model; /* enum virDomainShmemModel */
>
>    struct {
>
>        bool enabled;
>
>        virDomainChrSourceDef chr;
>
>    } server;
>
>    struct {
>
>        bool enabled;
>
>        unsigned vectors;
>
>        virTristateSwitch ioeventfd;
>
>    } msi;
>
>    virDomainDeviceInfo info;
>
>};
>
>[changed code]
>
>src/conf/domain_conf.c
>
>src/conf/domain_conf.h
>
>
>
>[Detail of Source Code Modification]
>
>
>diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
>index 9f75dc4..b41be37 100644
>--- a/src/conf/domain_conf.c
>+++ b/src/conf/domain_conf.c
>@@ -14665,7 +14665,6 @@ virDomainShmemDefParseXML(virDomainXMLOptionPtr xmlopt,
>     xmlNodePtr save = ctxt->node;
>     xmlNodePtr server = NULL;
>
>-
>     if (VIR_ALLOC(def) < 0)
>         return NULL;
>
>-
>     if (VIR_ALLOC(def) < 0)
>         return NULL;
>
>@@ -14685,12 +14684,28 @@ virDomainShmemDefParseXML(virDomainXMLOptionPtr xmlopt,
>         VIR_FREE(tmp);
>     }
>
>+
>     if (!(def->name = virXMLPropString(node, "name"))) {
>         virReportError(VIR_ERR_XML_ERROR, "%s",
>                        _("shmem element must contain 'name' attribute"));
>         goto cleanup;
>     }
>
>+
>+       if ((tmp = virXMLPropString(node, "master"))) {
>+               int val;
>+
>+               if ((val = virTristateSwitchTypeFromString(tmp)) <= 0) {
>+                       virReportError(VIR_ERR_XML_ERROR,
>+                                                  _("invalid ivshmem master setting for shmem: '%s'"),
>+                                                  tmp);
>+                       goto cleanup;
>+               }
>+               def->master = val;
>+               VIR_FREE(tmp);
>+       }
>+
>+
>     if (virDomainParseScaledValue("./size[1]", NULL, ctxt,
>                                   &def->size, 1, ULLONG_MAX, false) < 0)
>         goto cleanup;
>diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
>index f1e6e4e..615d721 100644
>--- a/src/conf/domain_conf.h
>+++ b/src/conf/domain_conf.h
>@@ -1727,8 +1727,10 @@ typedef enum {
>
>struct _virDomainShmemDef {
>     char *name;
>+
>     unsigned long long size;
>     int model; /* enum virDomainShmemModel */
>+   virTristateSwitch master;
>     struct {
>         bool enabled;
>         virDomainChrSourceDef chr;
>}

>--
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